tag:theconversation.com,2011:/au/topics/modelling-1924/articlesModelling – The Conversation2023-11-15T19:04:46Ztag:theconversation.com,2011:article/2177782023-11-15T19:04:46Z2023-11-15T19:04:46ZHow could Australia actually get to net zero? Here’s how<figure><img src="https://images.theconversation.com/files/559509/original/file-20231115-21-4neopd.jpg?ixlib=rb-1.1.0&rect=22%2C28%2C3811%2C2126&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Every bit of warming matters if we want to avoid the worst impacts for climate change, as the <a href="https://www.ipcc.ch/report/sixth-assessment-report-cycle">latest report</a> from the Intergovernmental Panel on Climate Change shows. </p>
<p>In 2020, we released modelling showing how Australia could get to net zero faster – and keep the Paris Agreement goal of holding warming to 1.5°C in play. Our new update shows this is still the case. </p>
<p>This week, we released our <a href="https://www.climateworkscentre.org/news/australia-can-still-decarbonise-in-line-with-the-paris-agreement/">latest modelling</a> based on cutting emissions in line with the 2015 Paris Agreement, which set an upper limit on warming of well below 2°C, with a commitment to strive for the lower harm limit of 1.5°C.</p>
<p>At present, the government’s 2030 goal is a 43% reduction from 2005 levels, with plans to set a further target for 2035 soon. Our new modelling of 1.5°C and well-below-2°C (1.8°C) pathways shows we must increase the pace of emissions cuts to between 48–66% for 2030 and 61%–85% for 2035. </p>
<p>This means Australia would reach net zero emissions by 2039, around a decade sooner than the current target of net zero by 2050. Our research shows this is possible. </p>
<p><iframe id="tc-infographic-979" class="tc-infographic" height="400px" src="https://cdn.theconversation.com/infographics/979/6e75228c4441731b7216d1175d0a951e4ab14cc2/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<h2>So how do you actually do this?</h2>
<p>In July, the government announced the development of net zero plans for six sectors: electricity and energy, industry, built environment, agriculture and land, transport and resources. Treasurer Jim Chalmers <a href="https://ministers.treasury.gov.au/ministers/jim-chalmers-2022/speeches/keynote-address-economic-and-social-outlook-conference">recently said</a> the government is preparing an ambitious policy agenda with <a href="https://www.smh.com.au/politics/federal/chalmers-plans-an-australian-way-to-slash-emissions-rebuild-economy-20231102-p5egxb.html">big spending</a> on green industries to help cut emissions, and to grow the economy as reliance on gas and coal falls. </p>
<p>These plans are now under development. Our modelling of these sectors shows which ones must cut emissions fastest – and how to do it for the least cost. </p>
<p><iframe id="tc-infographic-981" class="tc-infographic" height="400px" src="https://cdn.theconversation.com/infographics/981/a8672726ecaef46933402f360d6aa8e8e3f0be86/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<p><strong>Electricity:</strong> In these 1.5°C and well-below-2°C least-cost scenarios, the electricity sector reaches near zero between 2034 and 2038. Renewable energy is already the least-cost way to generate power. In turn, clean electricity can help decarbonise the rest of the economy. </p>
<p><strong>Industry and resources:</strong> In our scenarios, industrial emissions fall by 42% (well-below-2°C) or 54% (1.5°C) by 2035. By 2050, they fall by 54% and 67% respectively. Earlier and faster electrification and uptake of hydrogen technologies through the 2020s and 2030s drives more emissions reductions in the 1.5°C scenario.</p>
<p><strong>Buildings:</strong> Rapid emissions reductions in the building sector come from electrification and improvements in energy performance in both scenarios. Housing energy efficiency improves by 41% by 2050 compared to today’s levels.</p>
<p><strong>Agriculture and land:</strong> Cutting emissions in line with the 1.5°C goal will require much more removal of carbon dioxide from the atmosphere, mainly through sequestration in trees or soil. This can happen without damaging agricultural production. </p>
<p>How much CO₂ we need to pull from the air depends on our ambition. For the well-under-2°C scenario, we need to remove 1.4 billion tonnes (1.4 Gt). For 1.5°C, it’s 4.6 Gt. Farming emissions such as methane from livestock and nitrous oxide from fertilisers will take longer to cut, as emissions per, say, kilogram of beef falls while production increases overall. Adding algae to livestock feed and rolling out slow and controlled-release fertilisers may help lower emissions here.</p>
<p><strong>Transport:</strong> Without strong action on transport, emissions will keep growing. Both scenarios show minimal change in total transport sector emissions until 2030. That’s because steady increases in vehicle use as our population and economy grows will prevent overall reductions – even as people go electric. </p>
<p>Under both scenarios, the transport sector changes markedly. Electric vehicles (EVs) become dominant, making up 73% of new car sales under the 1.5°C scenario or 56% in the well-below-2°C scenario. Our modelling doesn’t account for the additional potential benefits of shifting trips from cars to public transport, or from road to rail freight.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/australia-finally-has-a-net-zero-authority-heres-what-should-top-its-agenda-205029">Australia finally has a Net Zero Authority – here's what should top its agenda</a>
</strong>
</em>
</p>
<hr>
<h2>For most sectors, net zero relies on clean electricity</h2>
<p>Our modelling suggests it’s most cost effective for Australia to rapidly switch fossil fuel electricity to renewable sources and push beyond the current 82% clean energy target by 2030. We should instead aim for between 83 and 90%, and almost 100% by 2050. </p>
<p>Coal-powered electricity generation disappears before 2035 in our 1.5°C scenario, and by late 2030s in our well-below-2°C scenario. Gas-powered electricity falls sharply around the same time period. </p>
<p><iframe id="tc-infographic-980" class="tc-infographic" height="400px" src="https://cdn.theconversation.com/infographics/980/af400a9c041b67b64d42dba12e10a3cd92c77251/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>By 2050, gas-fired power stations would contribute less than 1% of total generation, only firing up briefly to firm electricity supply to the grid.</p>
<p>Under both the 1.5°C and well-below-2°C scenarios, Australia’s electricity generation increases markedly. Renewable-powered electricity generation in 2030 would be greater than the total amount of electricity generated in 2020. By 2050, it is more than three times as great.</p>
<h2>The rise of hydrogen for hard-to-tackle sectors</h2>
<p>Support for green hydrogen <a href="https://www.iea.org/reports/global-hydrogen-review-2023/executive-summary">has soared</a> in recent years, both internationally and locally through government programs such as <a href="https://arena.gov.au/funding/hydrogen-headstart/">Hydrogen Headstart</a>.</p>
<p>Why the change? Because of its potential uses in hard-to-green sectors. Industrial processes such as steelmaking rely on high temperatures. Traditionally coal has been used, but hydrogen is emerging as an alternative. It may have a role in transport, through fuel-cell vehicles, and to replace gas in those industries that rely on high-temperature heat.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/559511/original/file-20231115-29-dv3rca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="molten steel rods in factory" src="https://images.theconversation.com/files/559511/original/file-20231115-29-dv3rca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/559511/original/file-20231115-29-dv3rca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559511/original/file-20231115-29-dv3rca.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559511/original/file-20231115-29-dv3rca.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559511/original/file-20231115-29-dv3rca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559511/original/file-20231115-29-dv3rca.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559511/original/file-20231115-29-dv3rca.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Steelmaking has long been seen as hard to decarbonise. But hydrogen may offer a path to do so.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Neither of our modelled scenarios show a role for hydrogen in buildings, passenger transport or short-haul freight. That’s because electrifying homes and using battery-electric vehicles is cheaper and more market-ready. </p>
<p>But our modelling shows hydrogen can play a role in industry, long-haul freight and maritime shipping – if it becomes commercially viable for these sectors.</p>
<p>In our scenarios, domestic hydrogen demand grows to between 383 and 465 petajoules by 2050 – around 12–16% of Australia’s energy demand. </p>
<h2>Time is more precious than ever</h2>
<p>Our latest analysis shows a 1.5°C least-cost pathway would see Australia reach net zero more than a decade earlier than the current goal of 2050.</p>
<p>If Australia and the rest of the world can cut emissions in line with the Paris Agreement goals, a safer and more prosperous future awaits.</p>
<p>But it’s only possible if Australia acts quickly, builds on the momentum towards net zero and seizes the enormous opportunities offered in fast decarbonisation.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-road-is-long-and-time-is-short-but-australias-pace-towards-net-zero-is-quickening-214570">The road is long and time is short, but Australia's pace towards net zero is quickening</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/217778/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anna Skarbek is on the board of the Centre for New Energy Technologies, the Green Building Council of Australia, Sentient Impact Group and the Asia-Pacific Advisory Board of the Glasgow Financial Alliance on Net Zero. She is a member of the Net Zero Economy Agency Advisory Board, the Grattan Institute’s energy program reference panel and the Blueprint Institute’s strategic advisory council.</span></em></p><p class="fine-print"><em><span>Anna Malos and Michael Li do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>It’s still possible for Australia to cut emissions in line with holding climate change to 1.5°C. Here’s how.Anna Skarbek, CEO, Climateworks CentreAnna Malos, Climateworks Centre - Country Lead, Australia, Monash UniversityMichael Li, Research and Analysis Manager, Climateworks Centre, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2064932023-06-12T20:01:24Z2023-06-12T20:01:24ZWe’re in another COVID wave. But it’s not like the others<figure><img src="https://images.theconversation.com/files/531031/original/file-20230608-17666-2sh956.jpg?ixlib=rb-1.1.0&rect=2%2C1%2C995%2C664&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/woman-public-transport-respirator-on-her-1943475565">Shutterstock</a></span></figcaption></figure><p>Each Omicron wave so far in Australia has had distinguishing features – the sharp rise and fall of BA.1, the widespread transmission among children and families in BA.2, a shift to more infections in older people with BA.5, then the confusing variant mix in the summer wave of 2022-23. </p>
<p>Now Australia is in its fifth Omicron wave, which has been brewing since February. But it has grown so slowly that many people may have not realised it until recent months.</p>
<p>Why has this most recent wave been so drawn out? And what has its real impact been on our health and health systems?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/531048/original/file-20230609-29-c8mspj.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/531048/original/file-20230609-29-c8mspj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531048/original/file-20230609-29-c8mspj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=384&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531048/original/file-20230609-29-c8mspj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=384&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531048/original/file-20230609-29-c8mspj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=384&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531048/original/file-20230609-29-c8mspj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=482&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531048/original/file-20230609-29-c8mspj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=482&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531048/original/file-20230609-29-c8mspj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=482&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Australia’s COVID cases and seven-day rolling average, showing how the latest wave is long and drawn out.</span>
<span class="attribution"><a class="source" href="https://www.health.gov.au/health-alerts/covid-19/weekly-reporting?language=und">health.gov.au</a></span>
</figcaption>
</figure>
<h2>Slower spread, less testing</h2>
<p>With <a href="https://kirby.unsw.edu.au/sites/default/files/COVID19-Blood-Donor-Report-Round4-Nov-Dec-2022.pdf">most people</a> in Australia now having been vaccinated against COVID, infected or both, we expect the virus to spread more slowly through the population.</p>
<p>This means the overall number of infections in the current wave should be fewer than in previous ones. Infections should also occur over a longer period of time.</p>
<p>But we also know people are mixing and socialising more than in previous waves. So it is easier for viruses such as SARS-CoV-2 (the virus that causes COVID) to be transmitted.</p>
<p>While these two factors counter each other, overall we expect to see reduced health impacts compared with previous waves.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/531050/original/file-20230609-15-9lenas.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Ambulance driving on tram tracks through Melbourne CBD, trams in background" src="https://images.theconversation.com/files/531050/original/file-20230609-15-9lenas.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531050/original/file-20230609-15-9lenas.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531050/original/file-20230609-15-9lenas.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531050/original/file-20230609-15-9lenas.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531050/original/file-20230609-15-9lenas.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531050/original/file-20230609-15-9lenas.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531050/original/file-20230609-15-9lenas.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">We expect fewer people with COVID going to hospital at this stage of the pandemic.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/melbourne-australia-march-26-2018-ambulance-1057060745">etsir/Shutterstock</a></span>
</figcaption>
</figure>
<p>We are <a href="https://www.health.gov.au/health-alerts/covid-19/weekly-reporting?language=und">already seeing</a> fewer people with confirmed infections and fewer people who are unwell requiring hospitalisation.</p>
<p>We also know from weekly surveys that people are less likely to test for COVID and report their results at this stage of the pandemic. So reported cases are now a smaller fraction of all infections than in previous waves.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/flu-or-covid-you-can-now-test-for-both-at-home-with-a-single-swab-heres-what-you-need-to-know-204119">Flu or COVID? You can now test for both at home with a single swab. Here's what you need to know</a>
</strong>
</em>
</p>
<hr>
<h2>New sub-variants are likely the cause</h2>
<p>The slow and drawn out nature of the current wave is most likely due to the sequential emergence and spread of new Omicron sub-variants. The current wave started with <a href="https://theconversation.com/the-kraken-subvariant-xbb-1-5-sounds-scary-but-behind-the-headlines-are-clues-to-where-covids-heading-198158">XBB.1.5</a>, then shifted to XBB.1.9.1 and XBB.1.9.2, then most recently <a href="https://theconversation.com/arcturus-what-to-know-about-the-new-covid-variant-omicron-xbb-1-16-204598">XBB.1.16</a>.</p>
<p>Each sub-variant has been able to spread where the <a href="https://theconversation.com/new-covid-variants-may-be-more-transmissible-but-that-doesnt-mean-the-r0-or-basic-reproduction-number-has-increased-186826">previous one could not</a>. But the competitive advantage of each has been minor. So we have only seen a progressive increase in infections as new sub-variants emerge, rather than the dramatic surges in infections and health impacts associated with previous variants.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1621458548940054530"}"></div></p>
<h2>Are we at the peak of the current wave?</h2>
<p>There is some debate about whether New South Wales has reached the peak of its wave. However, forecasts for most other jurisdictions suggest declines have begun or are imminent.</p>
<p>But as always, there is uncertainty in how the wave will develop, and we cannot exclude the possibility of sustained epidemic activity over a longer period.</p>
<p>Hospitalisations for those infected with COVID may stay elevated for a while longer. This is due both to the lag between infection and hospitalisation and we are seeing a shift in infections to older people as the wave progresses. </p>
<p>Thankfully, we do not expect the health system to come under the pressure from COVID seen during the BA.5 wave in winter 2022. This is good news.</p>
<p>However, for the first time in Australia, the SARS-CoV-2 wave may coincide almost completely with influenza and RSV (respiratory syncytial virus) waves. This certainly appears <a href="https://www.health.nsw.gov.au/Infectious/covid-19/Documents/weekly-covid-overview-20230603.pdf">likely in NSW</a>. The combined impact of these three viruses may be significant.</p>
<p>Looking ahead, this combined threat will need careful attention. Surveillance systems need to be (re-)designed to detect, anticipate and forecast the <a href="https://arxiv.org/abs/2306.01224">combined burden</a> of acute viral respiratory infections.</p>
<p>We expect COVID to contribute to the increased burden of seasonal respiratory diseases over the next few years, and perhaps well beyond.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/i-need-a-flu-shot-and-a-covid-booster-can-i-get-them-at-the-same-time-204027">I need a flu shot and a COVID booster. Can I get them at the same time?</a>
</strong>
</em>
</p>
<hr>
<h2>How about future waves?</h2>
<p>Future COVID waves are likely to become much more predictable, and coincide with winter. While this is somewhat speculative, it is consistent with how other respiratory viruses behave.</p>
<p>What might this look like? In the United Kingdom all COVID indicators have seen a <a href="https://coronavirus.data.gov.uk/">major decline</a> after winter. We see similar patterns in other temperate northern hemisphere countries, such as the <a href="https://covid.cdc.gov/covid-data-tracker/#trends_weeklyhospitaladmissions_select_00">United States</a>.</p>
<p>Although there are <a href="https://theconversation.com/deltacron-what-scientists-know-so-far-about-this-new-hybrid-coronavirus-179442">other</a> <a href="https://interactives.stuff.co.nz/2022/covid-19-cases-new-zealand/">contenders</a>, internationally, it is likely that the next wave of COVID will also be caused by a sub-variant of XBB.</p>
<p>Without a clear successor to XBB.1.16 identified at present, a new wave will likely only form as genetic mutations accumulate during the next northern winter. </p>
<p>During that time (our Australian summer) people will travel between Australia and the northern hemisphere, re-importing these newer variants into Australia. As conditions in Australia change (next autumn) and the risk of transmission increases, a new wave may develop, peaking in the winter of 2024.</p>
<h2>Alpha, Delta, Omicron waves</h2>
<p>Of course, we have seen COVID behave very differently to this over the past three years. The Alpha, Delta and then Omicron variants appeared and spread across the globe causing large and often devastating waves. </p>
<p>But they occurred at a fundamentally different period of the pandemic, where small changes in the virus had dramatic consequences for transmission and our health. </p>
<p>Recent changes to the virus have provided far less advantage, suggesting such transformative events are now far less likely.</p>
<p>Still, we should maintain sufficient surveillance to keep an eye on emerging sub-variants (genomics), case numbers and hospitalisations – all essential if we are to protect our health and wellbeing.</p><img src="https://counter.theconversation.com/content/206493/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Wood receives funding from NSW Health and the National Health and Medical Research Council for projects on COVID-19. He has previously received funding from the federal government as part of COVID responses in 2020-21 and from WHO Western Pacific Regional Office in 2020. He is a current member of the Australian Technical Advisory Committee on Immunisation.</span></em></p><p class="fine-print"><em><span>Freya Shearer receives funding from the National Health and Medical Research Council, the Australian Government Departments of Health and Foreign Affairs and Trade, and NSW Health.</span></em></p><p class="fine-print"><em><span>James McCaw receives funding from the Australian Government Departments of Health and Foreign Affairs and Trade, the Australian Research Council and the National Health and Medical Research Council. He is an invited expert member of the Communicable Disease Network of Australia and between January 2020 and May 2022 was an invited expert member of the Australian Health Protection Principal Committee.</span></em></p>Australia is in the middle of its fifth Omicron wave, which has been brewing since February. But it’s been slow and drawn out and the health impacts are very different to earlier waves.James Wood, Professor, epidemiological modelling of infectious diseases, UNSW SydneyFreya Shearer, Research Fellow, Epidemic Decision Support, The University of MelbourneJames McCaw, Professor in Mathematical Biology, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1958162022-12-11T19:06:17Z2022-12-11T19:06:17ZDid physicists make a wormhole in the lab? Not quite, but a new experiment hints at the future of quantum simulations<figure><img src="https://images.theconversation.com/files/499159/original/file-20221206-26-iagjnl.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Scientists made headlines last week for supposedly generating a wormhole. The research, reported in <a href="https://www.nature.com/articles/s41586-022-05424-3">Nature</a>, involves the use of a quantum computer to simulate a wormhole in a simplified model of physics. </p>
<p>Soon after the news broke, physicists and experts in quantum computing <a href="https://www.math.columbia.edu/%7Ewoit/wordpress/?p=13181">expressed scepticism</a> that a wormhole had in fact been created. </p>
<p>Media coverage was chaotic. Outlets reported that physicists had created a <a href="https://scitechdaily.com/physicists-create-theoretical-wormhole-using-quantum-computer/">theoretical wormhole</a>, a <a href="https://www.quantamagazine.org/physicists-create-a-wormhole-using-a-quantum-computer-20221130/">holographic wormhole</a> or perhaps a <a href="https://www.nytimes.com/2022/11/30/science/physics-wormhole-quantum-computer.html">small, crummy wormhole</a>, and that Google’s quantum computer suggests <a href="https://bigthink.com/hard-science/google-quantum-computer-wormholes-real/">wormholes are real</a>. Other outlets soberly offered the news that no, <a href="https://arstechnica.com/science/2022/12/no-physicists-didnt-make-a-real-wormhole-what-they-did-was-still-pretty-cool/amp/">physicists didn’t make a wormhole at all</a>.</p>
<p>If this has you confused, you’re not alone! What’s going on? </p>
<h2>Wormholes and entanglement</h2>
<p>The Universe is vast. It’s so big that travelling from one side to the other by conventional means is impractical. </p>
<p>Wormholes are a kind of loophole: shortcuts between two regions of the Universe that might allow one to traverse vast distances in a much shorter time. Wormholes are permitted by Einstein’s theory of relativity, but none have ever been found in nature. </p>
<figure class="align-center ">
<img alt="An illustration showing a wormhole joining points in space." src="https://images.theconversation.com/files/499921/original/file-20221209-19531-zuzz68.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499921/original/file-20221209-19531-zuzz68.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499921/original/file-20221209-19531-zuzz68.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499921/original/file-20221209-19531-zuzz68.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499921/original/file-20221209-19531-zuzz68.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499921/original/file-20221209-19531-zuzz68.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499921/original/file-20221209-19531-zuzz68.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A wormhole is a hypothetical ‘shortcut’ between two regions of space.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/tunnel-wormhole-over-curved-spacetime-travelling-721550755">Shutterstock</a></span>
</figcaption>
</figure>
<p>Recently, physicists have been <a href="https://arxiv.org/abs/1412.8483">toying with the idea</a> that wormholes are related to another phenomenon, known as entanglement. </p>
<p>Entanglement is a peculiar, quantum phenomenon involving particles. When particles are put into an entangled state, measurement of one particle seems to affect the other particle immediately. This is the case even when the two particles are too far apart for causation to be possible. </p>
<p>Some physicists have suggested that a wormhole may just be a way of describing a certain kind of quantum entanglement. If correct, this would forge a link between two prominent theories of physics: quantum mechanics and general relativity. </p>
<p>General relativity explains how gravity works, and describes the Universe on large scales. Quantum mechanics explains the other fundamental forces, and describes the Universe on very small scales.</p>
<figure class="align-center ">
<img alt="Illustration showing two glowing particles connected by faint lines." src="https://images.theconversation.com/files/499923/original/file-20221209-23880-p3m533.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499923/original/file-20221209-23880-p3m533.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499923/original/file-20221209-23880-p3m533.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499923/original/file-20221209-23880-p3m533.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499923/original/file-20221209-23880-p3m533.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=452&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499923/original/file-20221209-23880-p3m533.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=452&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499923/original/file-20221209-23880-p3m533.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=452&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In quantum mechanics, ‘entanglement’ is a kind of link between particles that may be quite distant from one another.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Both are extremely successful theories. However, they are yet to be reconciled into a single, unified theory. </p>
<p>A unified theory would preserve the insights of both quantum mechanics and general relativity, while at the same time providing an account of how gravity works in the quantum domain, something we don’t currently understand.</p>
<p>Because wormholes are distinctive of general relativity, and entanglement is distinctive of quantum mechanics, the potential similarity between them is exciting. It suggests the two theories may, at some level, be describing the very same thing.</p>
<h2>Quantum gravity on a chip?</h2>
<p>How would we look for this potential similarity between wormholes and entanglement? </p>
<p>Well, we know how to entangle particles experimentally. We’ve been doing that for some time. </p>
<p>So we can try to build a particular kind of quantum system: one that can be described using the same physics we use for wormholes. If we can build such a system in the lab and it behaves like a wormhole, it would support the idea that entanglement and wormholes are two sides of the same coin. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-quantum-computation-and-communication-technology-7892">Explainer: quantum computation and communication technology </a>
</strong>
</em>
</p>
<hr>
<p>In quantum computers, the basic components can be put into various quantum states that can be used to run quantum experiments. So, it seems they present an opportunity to test the relationship between wormholes and entanglement. </p>
<p>This is perhaps why it was reported that physicists had used a quantum computer to generate a wormhole. But that does not seem to be what actually happened, though understanding why is not straightforward. </p>
<h2>Not a wormhole</h2>
<p>What physicists did was organise the basic components of a quantum computer into a specific quantum state. They were then able to transfer information from one part of the computer to another through the quantum system. </p>
<p>The quantum system, and the way the information was transferred, can be described using a <a href="https://en.wikipedia.org/wiki/Sachdev%E2%80%93Ye%E2%80%93Kitaev_model">particular model</a> in physics. According to this model, the kind of information transfer that occurred within the computer is descriptively similar to the way that something passes through a wormhole. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-are-wormholes-an-astrophysicist-explains-these-shortcuts-through-space-time-187828">What are wormholes? An astrophysicist explains these shortcuts through space-time</a>
</strong>
</em>
</p>
<hr>
<p>However, the model being used has at least two limitations. </p>
<p>First, it appears to make unrealistic assumptions about the physics of our world. It assumes, in particular, that spacetime – the fabric of the Universe – has certain properties that it may not have. </p>
<p>Second, the model has been simplified to describe a simple system that can be implemented with a quantum computer. Such a simplified model may be physically inaccurate.</p>
<p>So while we can describe what happened within the computer as though it were a wormhole, using a specific kind of model, it is unclear whether the model represents the world as we know it. </p>
<h2>Experiment and simulation</h2>
<p>Some commentators have offered a different reason to be sceptical that a wormhole was created: it was just a simulation. As <a href="https://futurism.com/headlines-building-wormhole-nonsense">one critic</a> put it, taking the system to be a wormhole “is like claiming that playing the videogame Portal involves creating an actual wormhole because it depicts something akin to the theoretical concept onscreen”. </p>
<p>We must indeed be careful about drawing inferences about reality from simulations. However, the quantum aspect of this simulation makes it more like an experiment than the ordinary simulation you might run on an everyday computer.</p>
<p>So it seems the simulation may legitimately tell us something about the quantum system it is simulating. However, the problem remains that we can only interpret the system as a wormhole in a specific, potentially unrealistic model of physics.</p>
<h2>No wormholes, but still impressive</h2>
<p>So we should perhaps be sceptical that any wormholes were created. Still, there is reason to be impressed. </p>
<p>For one thing, the team used machine-learning techniques to simplify the model they were using to simulate it in a useful way.</p>
<p>The use of machine learning to produce the simplified model is neat, and we should expect to see more uses of machine learning like this in the future.</p>
<p>It’s also important that a quantum computer was used to run the type of quantum experiment at issue. That this can be done at all opens the way toward running further experiments. This may open up an experimental paradigm that can be used to make progress in physics.</p>
<p>There is also the possibility – albeit rather distant – that some aspect of the model that was used to describe the quantum system will be vindicated. This may lead to the discovery of a relationship between quantum entanglement and wormholes in the future. </p>
<p>But this remains very speculative.</p><img src="https://counter.theconversation.com/content/195816/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sam Baron receives funding from the Australian Research Council.</span></em></p>When it comes to physics experiments, quantum simulations aren’t quite the real thing – but in some cases they’re much closer than you’d expect.Sam Baron, Associate Professor, Philosophy of Science, Australian Catholic UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1944442022-11-15T19:08:34Z2022-11-15T19:08:34ZWhat can we expect from this latest COVID wave? And how long is it likely to last?<p>Australia is now mid-way into its fourth wave of COVID in the Omicron era, driven by a rich soup of Omicron descendants. Unlike previous waves, where a single new variant of SARS-CoV-2 variant such as BA.2 or BA.5 was responsible, we have had an explosion of <a href="https://www.health.nsw.gov.au/Infectious/covid-19/Documents/weekly-covid-overview-20221105.pdf">new variants</a> such as XBB.1, BQ.1.1 and BR.2.1. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1590650171280437249"}"></div></p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/from-centaurus-to-xbb-your-handy-guide-to-the-latest-covid-subvariants-and-why-some-are-more-worrying-than-others-192945">From Centaurus to XBB: your handy guide to the latest COVID subvariants (and why some are more worrying than others)</a>
</strong>
</em>
</p>
<hr>
<p>However, despite this apparent diversity, these new variants all follow a similar script, where the same set of changes have evolved independently across multiple variants. This is called convergent evolution.</p>
<p>These changes make the virus better at infecting people with immunity to existing variants. Since mid-October, the subvariants’ ability to escape immunity from vaccination and/or previous infection has been potent enough to cause a new wave in Australia. </p>
<p>The graph below shows the series of 2022 waves, with the original Omicron the first wave, followed by the double-bump BA.2 (where Western Australia had different timing), the winter BA.5 wave, and now a new upswing in November. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/495218/original/file-20221114-17-44kkrd.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/495218/original/file-20221114-17-44kkrd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/495218/original/file-20221114-17-44kkrd.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=512&fit=crop&dpr=1 600w, https://images.theconversation.com/files/495218/original/file-20221114-17-44kkrd.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=512&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/495218/original/file-20221114-17-44kkrd.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=512&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/495218/original/file-20221114-17-44kkrd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=643&fit=crop&dpr=1 754w, https://images.theconversation.com/files/495218/original/file-20221114-17-44kkrd.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=643&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/495218/original/file-20221114-17-44kkrd.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=643&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://ourworldindata.org/coronavirus/country/australia">Johns Hopkins University CSSE COVID-19 Data</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In some good news, this wave is likely to be a shorter and smaller version of the BA.5 wave. Here’s why.</p>
<h2>Cases are rising rapidly</h2>
<p>In Australia, the wave is already growing rapidly, with indicators such as <a href="https://www.health.gov.au/health-alerts/covid-19/case-numbers-and-statistics">recorded cases and hospital occupancy</a> showing significant increases in multiple states over the last two weeks. </p>
<p>New South Wales reports on the <a href="https://www.health.nsw.gov.au/Infectious/covid-19/Documents/weekly-covid-overview-20221105.pdf">trend in the underlying variants</a>, with a clear shift since early October. </p>
<p>Removal of mandatory reporting and isolation has led to fewer rapid antigen tests (RATs) being reported. So we may only be recording a smaller fraction of all community infections now than in previous waves. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/previous-covid-infection-may-not-protect-you-from-the-new-subvariant-wave-are-you-due-for-a-booster-193292">Previous COVID infection may not protect you from the new subvariant wave. Are you due for a booster?</a>
</strong>
</em>
</p>
<hr>
<p>In the graph below, I’ve used the <a href="https://github.com/epiforecasts/EpiNow2">EpiNow2 R package</a> (an open-source estimation and forecasting tool) to calculate the trend in the effective reproduction number (Rt) using <a href="https://data.nsw.gov.au/search/dataset/ds-nsw-ckan-aefcde60-3b0c-4bc0-9af1-6fe652944ec2/details?q=">NSW case data</a> since early September. </p>
<p>Rt represents the average number of people that a single COVID case infects at a given point in time. Epidemics decline when Rt is less than 1, while epidemic growth becomes likely once Rt is above 1 and is increasingly steep as Rt rises. This is now substantially above 1 in New South Wales:</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/495045/original/file-20221114-22-r5uyoz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/495045/original/file-20221114-22-r5uyoz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=248&fit=crop&dpr=1 600w, https://images.theconversation.com/files/495045/original/file-20221114-22-r5uyoz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=248&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/495045/original/file-20221114-22-r5uyoz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=248&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/495045/original/file-20221114-22-r5uyoz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=312&fit=crop&dpr=1 754w, https://images.theconversation.com/files/495045/original/file-20221114-22-r5uyoz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=312&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/495045/original/file-20221114-22-r5uyoz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=312&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Trend in the effective reproduction number (Rt) in NSW as estimated from PCR case series (produced using the EpiNow2 R package).</span>
</figcaption>
</figure>
<h2>Will the wave peak by Christmas? Lessons from Singapore</h2>
<p>I think the most likely outcome is the wave will peak by Christmas. In my own work for NSW Health, I am currently projecting a peak in NSW for the first week of December. </p>
<p>But these predictions are uncertain because it is still difficult to estimate the level of protection against infection in our population, despite impressive <a href="https://www.biorxiv.org/content/10.1101/2022.09.15.507787v4.full.pdf">near real-time laboratory science</a> that is helping to characterise this.</p>
<p>Fortunately, despite the challenges with modelling, the recent Singapore wave can guide our expectations. Caused by XBB.1, this wave was short and sharp, peaking around October 18 and then dropping back almost to <a href="https://www.moh.gov.sg/#7-day-moving-average-of-local-cases">pre-wave levels</a> by November 12. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/xbb-and-bq-1-what-we-know-about-these-two-omicron-cousins-193591">XBB and BQ.1: what we know about these two omicron 'cousins'</a>
</strong>
</em>
</p>
<hr>
<p>Singapore has also seen a <a href="https://www.moh.gov.sg/docs/librariesprovider5/local-situation-report/ceg_20221026_weekly_report_on_covid-19.pdf">significant increase in hospitalisations</a>, primarily in people aged above 70. </p>
<p>However cumulative cases, admissions and deaths are tracking to be about half those of their BA.5 wave, with no signs of increased severity. </p>
<p>Despite the ability of XBB.1 to evade vaccination and/or previous infection, in Singapore people with prior Omicron infections were about <a href="https://www.moh.gov.sg/docs/librariesprovider5/default-document-library/annexad79528af5784a1b8c95c986c82e3131.pdf">75% less likely</a> to test positive in this wave than in people without recorded prior infections. </p>
<p>Singapore has also had quite a similar COVID pandemic experience to Australia in terms of restrictions, vaccination and infection waves. One exception is that mask-wearing remains more prevalent in Singapore.</p>
<figure class="align-center ">
<img alt="People wear masks on a Singapore train" src="https://images.theconversation.com/files/495229/original/file-20221115-19-vqsivk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/495229/original/file-20221115-19-vqsivk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/495229/original/file-20221115-19-vqsivk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/495229/original/file-20221115-19-vqsivk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/495229/original/file-20221115-19-vqsivk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/495229/original/file-20221115-19-vqsivk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/495229/original/file-20221115-19-vqsivk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Singaporeans are more likely to wear masks than Australians.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/singapore-may2020-covid19-mrt-train-passengers-1749639923">Shutterstock</a></span>
</figcaption>
</figure>
<p>We should, however, expect some differences. Australia has about six times the resident population of Singapore with widely separated population centres. This might mean the wave duration across Australia is one to two weeks longer. </p>
<p>Australia also has a higher proportion of the population above 75, a large fraction of whom <a href="https://kirby.unsw.edu.au/sites/default/files/COVID19-Blood-Donor-Report-Round3-Aug-Sep-2022.pdf">haven’t had COVID</a> this year and therefore won’t have hybrid immunity (from both vaccination and prior infection). This could result in more hospital admissions and deaths per capita than in Singapore. </p>
<p>But in general, the Singapore wave supports the prediction this fourth Australian wave of 2022 will peak in early December and fall back below current levels by Christmas.</p>
<h2>Is this the new normal? What can we expect in the years to come?</h2>
<p>Beyond this year, I’m encouraged by the shift in pattern from single variants causing waves to the evolving variant soup. This evolution has been very rapid recently but there are signs this may slow considerably in 2023. </p>
<p>Firstly, the rate at which mutations occur is proportional to how much virus is circulating. The enormous number of COVID infections across this year mean that in 2022 this change has happened quickly but with each wave getting smaller, this rate of change should slow. </p>
<p>The recent variant soup evolution may also be a positive sign. The different variants in the soup have all gained a transmission advantage following the same immune-escape strategy. The set of relevant mutations were in fact predicted in advance by researchers at the University of Washington.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1551540513655754752"}"></div></p>
<p>If you are infected with one of these new variants, you should also have strong protection to the rest of the soup. The absence of big mutational jumps in dominant variants suggests SARS-CoV2, the virus that causes COVID, may now be entering a period of slower, more continuous evolution. This is <a href="https://www.cdc.gov/flu/about/viruses/change.htm">what we see for seasonal influenza</a>.</p>
<p>COVID has been full of surprises but the evidence suggests we could see SARS-CoV-2 infections fall below our recent trough levels in 2023 and the beginning of a more seasonal pattern to COVID waves.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-havent-i-had-covid-yet-193861">Why haven't I had COVID yet?</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/194444/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Wood receives funding from NSW Health and the NHMRC. He is a voting member of the Australian Technical Advisory Committee on Immunisation and is a member of the Variants of Concern subgroup of the Communicable Diseases Genomics Network of Australia. </span></em></p>The evidence so far suggests this wave could be a shorter and smaller version of the Omicron BA.5 wave.James Wood, Associate Professor, epidemiological modelling of infectious diseases, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1824202022-07-11T20:03:51Z2022-07-11T20:03:51ZBanning artificial stone could prevent 100 lung cancers and 1,000 cases of silicosis, where dust scars the lungs<figure><img src="https://images.theconversation.com/files/473304/original/file-20220711-14-dgmvla.jpg?ixlib=rb-1.1.0&rect=20%2C31%2C3473%2C2294&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/man-work-clothes-gloves-polishes-marble-1202772427">Shutterstock</a></span></figcaption></figure><p>Silica dust is a very fine dust produced when products such as bricks, concrete and pavers are cut or drilled. Artificial stone, which is used mainly for kitchen benchtops, is a <a href="https://theconversation.com/renovating-your-kitchen-help-australias-tradies-avoid-silicosis-by-not-choosing-artificial-stone-156208">particularly potent source</a> of silica dust. </p>
<p>Breathing this dust into the lungs can cause severe long-term damage. This can <a href="https://theconversation.com/engineered-stone-benchtops-are-killing-out-tradies-heres-why-a-bans-the-only-answer-126489">result in</a> breathing difficulties, scarring of the lungs (silicosis) and lung cancer.</p>
<p>In our <a href="https://about.curtin.edu.au/wp-content/uploads/sites/5/2022/07/FEFreport_formatted.pdf">recently published report</a>, we estimate that without action, Australian workers would develop more than 10,000 future lung cancers and almost 104,000 silicosis cases during their lifetime due to their exposure to silica dust. This is around 1% of all future lung cancers in the Australian adult population. </p>
<p>However, banning artificial stone would reduce silica exposure and could prevent 100 lung cancers and almost 1,000 silicosis cases over the lifetime of these workers. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-is-silicosis-and-why-is-this-old-lung-disease-making-a-comeback-80465">Explainer: what is silicosis and why is this old lung disease making a comeback?</a>
</strong>
</em>
</p>
<hr>
<h2>Re-emergence of an old disease</h2>
<p>Silica dust is a serious hazard in Australian workplaces. Around <a href="https://pubmed.ncbi.nlm.nih.gov/26888888/">7% of Australian workers</a> are at risk of breathing it in. Exposure is most common in miners and construction workers. </p>
<p>For the last 60 years, silicosis was very rare in Australia. Due to the increased use of artificial stone, we are now <a href="https://theconversation.com/explainer-what-is-silicosis-and-why-is-this-old-lung-disease-making-a-comeback-80465">seeing a re-emergence</a> of this terrible disease.</p>
<p>In response to the resurgence of silicosis, the Australian government set up a <a href="https://www1.health.gov.au/internet/main/publishing.nsf/Content/ohp-nat-dust-disease-taskforce.htm">taskforce</a> to improve the health and safety of those working with silica dust. Its final report, from June 2021, recommended further analysis on how best to protect artificial stone workers. </p>
<p>This is now under way, with Safe Work Australia releasing a regulatory impact statement for <a href="https://engage.swa.gov.au/cris-managing-the-risks-of-respirable-crystalline-silica">consultation</a>. This statement looks at a number of options to reduce exposure to silica and the cost of these over the next ten years. </p>
<p>Safe Work Australia concluded these measures would only need to save about five people a year from silicosis in order for these options to be cost effective. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1538702320120102912"}"></div></p>
<p>While this is a good start, there’s scope to do much more. Banning artificial stone is among the recommendations suggested by the taskforce but <a href="https://www1.health.gov.au/internet/main/publishing.nsf/Content/ohp-dust-occupational-disease.htm">not currently supported by government</a> and <a href="https://ehq-production-australia.s3.ap-southeast-2.amazonaws.com/194bd57754dab582a564c67315a2ee37112572d1/original/1656545533/5c2b36be2733fdd1a02881939d9e95bd_consultation-RIS-managing-risks-crystalline-silica-at_work.pdf?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIBJCUKKD4ZO4WUUA%2F20220711%2Fap-southeast-2%2Fs3%2Faws4_request&X-Amz-Date=20220711T052238Z&X-Amz-Expires=300&X-Amz-SignedHeaders=host&X-Amz-Signature=a386cd6e0d10be6cd4814c972521923d99d9a969e94c32d90eb2cd23e914b9d7">not being considered by Safe Work Australia</a>. </p>
<h2>Assessing the harm</h2>
<p>To estimate the harm caused by silica dust at work, we used <a href="https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-016-3066-1">a method</a> which calculates how many additional disease cases would occur in workers exposed to silica dust in one year – in this case, the year 2016. </p>
<p>We used <a href="https://oem.bmj.com/content/71/1/55.short">past exposure surveys</a> and recent reports from <a href="https://www.nsw.gov.au/sites/default/files/2021-08/case-finding-study-respirable-crystalline-silica-exposure-nsw-manufactured-stone-industry.pdf">New South Wales</a> and <a href="https://www.worksafe.vic.gov.au/resources/silica-associated-lung-disease-health-screening-research-project-phase-two-final-report">Victoria</a> to estimate how many workers were exposed to silica dust nationwide. </p>
<p>Then we modelled how many lung cancers and silicosis cases would occur during the lifetimes of these workers. </p>
<p>We then looked at possible ways to reduce exposure to silica dust, including wet cutting, reducing worker access to dusty areas, using good quality and well-fitted respirators, as well as banning artificial stone. </p>
<p>While this modelling isn’t yet published in a peer-reviewed journal, it has been peer-reviewed by others in the field. </p>
<h2>Reducing the harm</h2>
<p>We found banning artificial stone could prevent 100 lung cancers and almost 1,000 silicosis cases. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/engineered-stone-benchtops-are-killing-our-tradies-heres-why-a-bans-the-only-answer-126489">Engineered stone benchtops are killing our tradies. Here's why a ban's the only answer</a>
</strong>
</em>
</p>
<hr>
<p>We also looked at other control measures which could be implemented in the interim. </p>
<p>Setting up exclusion zones around areas where artificial stone is cut, using well-fitted respirators, wetting artificial stone while cutting it, and using on-tool dust extraction while cutting artificial stone could prevent cases of lung cancer and silicosis, but not as many as a complete ban.</p>
<figure class="align-center ">
<img alt="Man cuts stone." src="https://images.theconversation.com/files/473320/original/file-20220711-18-jtohev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473320/original/file-20220711-18-jtohev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473320/original/file-20220711-18-jtohev.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473320/original/file-20220711-18-jtohev.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473320/original/file-20220711-18-jtohev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473320/original/file-20220711-18-jtohev.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473320/original/file-20220711-18-jtohev.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Well-fitting respirators can reduce the risk.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/woodworking-carpenter-furniture-hand-cuting-skills-2136009577">Shutterstock</a></span>
</figcaption>
</figure>
<p>Unfortunately, a ban on silica dust in other industries such as mining isn’t possible. However, exposure can be reduced. Stopping workers from entering areas near crushers on mine sites would prevent 750 lung cancers and almost 7,500 silicosis cases. </p>
<p>If we were able to reduce exposure in the mining industry to that experienced by the general population, we could save more than 2,300 lung cancers and over 20,000 silicosis cases. </p>
<h2>Reducing silica dust would save lives</h2>
<p>Overall, ensuring compliance with engineering controls and respiratory equipment could prevent more than 400 workers from developing two terrible diseases. </p>
<p>These cases can only be prevented if there is 100% compliance with control measures. This is a level of compliance <a href="https://www.nsw.gov.au/sites/default/files/2021-08/case-finding-study-respirable-crystalline-silica-exposure-nsw-manufactured-stone-industry.pdf">much higher</a> than what we’re currently seeing in Australian workplaces. </p>
<p>A <a href="https://www.worksafe.vic.gov.au/engineered-stone-licence">licensing system</a> for artificial stone businesses such as that underway in Victoria might go some way to improving compliance, but the effects of this remain to be seen. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/renovating-your-kitchen-help-australias-tradies-avoid-silicosis-by-not-choosing-artificial-stone-156208">Renovating your kitchen? Help Australia's tradies avoid silicosis by not choosing artificial stone</a>
</strong>
</em>
</p>
<hr>
<p>However, if we banned artificial stone, we could save up to 700 more young workers from developing these diseases. If we tried to eliminate silica dust exposure in other industries, we could prevent even more disease. </p>
<p>Clearly, much more needs to be done to protect our workers from these ultimately preventable lung diseases.</p><img src="https://counter.theconversation.com/content/182420/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This report was commissioned by the Australian Council of Trade Unions (ACTU). </span></em></p><p class="fine-print"><em><span>Lin Fritschi does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Artificial stone, which is used mainly for kitchen benchtops, is a potent source of silica dust, which can scar the lung and cause lung cancer. Banning artificial stone could save lives.Renee Carey, Senior Research Fellow, Curtin UniversityLin Fritschi, Professor of Epidemiology, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1842112022-06-16T14:54:01Z2022-06-16T14:54:01ZSports Illustrated Swimsuit: Is inclusive objectification something to celebrate?<figure><img src="https://images.theconversation.com/files/467314/original/file-20220606-16-nfbo5a.jpg?ixlib=rb-1.1.0&rect=5%2C0%2C3994%2C1277&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The swimsuit issue continues to promote sexual attractiveness as women’s main currency.</span> <span class="attribution"><span class="source">(Sports Illustrated Swimsuit 2022)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/sports-illustrated-swimsuit--is-inclusive-objectification-something-to-celebrate" width="100%" height="400"></iframe>
<p>The last two weeks of May generated a flurry of celebratory media commentary about the diversity of models in the <a href="https://swimsuit.si.com/model-years/2022">2022 Sports Illustrated Swimsuit Issue</a>. It was praised for “<a href="https://www.thestreet.com/lifestyle/sports/si-swimsuit-issue-maye-musk-breaks-barriers-cover-model-at-74">breaking barriers</a>,” “<a href="https://www.businesswire.com/news/home/20220516005285/en/Kim-Kardashian-Ciara-Maye-Musk-and-Yumi-Nu-Are-Revealed-as-Sports-Illustrated-Swimsuit%E2%80%99s-2022-Cover-Models">empowering women</a>” and “<a href="https://www.goodmorningamerica.com/style/story/sports-illustrated-swimsuit-2022-maye-musk-kim-kardashian-84748799">trailblazing</a>.”</p>
<p>This year’s firsts included: Ashley Callingbull (<a href="https://thehill.com/changing-america/respect/diversity-inclusion/3492947-indigenous-first-nations-woman-featured-in-sports-illustrated-swimsuit-edition-for-first-time/">the first Indigenous model</a>), Yumi Nu (<a href="https://swimsuit.si.com/swimsuit/model/yumi-nu-2022-si-swimsuit-photos">the first Asian American curve model to appear on the cover</a>), Maye Musk (<a href="https://people.com/style/maye-musk-sports-illustrated-swimsuit-2022-cover-at-74-something-i-could-never-dream-up/">the first woman in her 70s</a>), Kelly Hughes (<a href="https://www.thecut.com/2022/05/a-model-with-a-c-section-scar-is-in-sports-illustrated.html">the first swimsuit model to show her C-section scars</a>) and Katrina Scott (<a href="https://swimsuit.si.com/swimnews/katrina-scott-first-visibly-pregnant-woman-in-si-swimsuit">the first visibly pregnant model</a>). </p>
<p>In recent years the magazine has highlighted more diversity, including <a href="https://swimsuit.si.com/swimnews/halima-aden-si-swimsuit-2019-model-kenya">Halima Aden in a burkini</a>, more <a href="https://parade.com/1381969/allienelson/athletes-sports-illustrated-swimsuit/">athletes</a>, trans models like <a href="https://www.npr.org/2021/07/20/1018381498/sports-illustrateds-swimsuit-issue-trans-model-leyna-bloom">Leyna Bloom</a> and <a href="https://www.forbes.com/sites/carlieporterfield/2020/07/10/valentina-sampaio-becomes-first-trans-model-in-sports-illustrateds-swimsuit-issue/">Valentina Sampaio</a> and more <a href="https://swimsuit.si.com/swimsuit/model/hunter-mcgrady">curve models like Hunter McGrady</a>.</p>
<p>But most of the models are still stereotypically young, thin and white. </p>
<p>With the celebration of firsts, an important question falls by the wayside: Is including a broader range of women in the pages of a magazine issue whose sole commercial purpose is to present them as sexual objects for a mostly straight male readership a good thing? </p>
<h2>‘Properly feminine’</h2>
<p>I am a feminist philosopher who works on <a href="https://global.oup.com/academic/product/moral-responsibility-in-collective-contexts-9780199782963">responsibility in oppressive social contexts</a> and co-founder of the blog <a href="https://fitisafeministissue.com/">Fit Is a Feminist Issue</a>. In society, where sexist structures and attitudes are abound, women’s value — and by extension, <a href="https://www.abc.net.au/everyday/how-a-womans-glam-appearance-affects-her-career/11671912">range of opportunities — is frequently determined by their attractiveness and sexual desirability to straight men</a>. So I question whether expanding the field of women who are sufficiently sexy and, <a href="https://www.routledge.com/Femininity-and-Domination-Studies-in-the-Phenomenology-of-Oppression/Bartky/p/book/9780415901864">to borrow the words of philosopher Sandra Bartky</a>, “properly feminine” to “merit” inclusion in the swimsuit issue, constitutes overall meaningful progress for women. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1531645368659849217"}"></div></p>
<p>Granted, there is something to be said for <a href="https://bpr.berkeley.edu/2019/12/20/one-size-does-not-fit-all-the-rise-of-diverse-fashion-models/">challenging the stereotypical esthetic ideals of normative femininity with diverse models</a>. And even though <a href="https://www.shape.com/celebrities/news/kate-upton-body-attention-criticism">model Kate Upton expressed discomfort about the public scrutiny and discussion of her body</a>, others, including Yumi Nu, describe appearing in the swimsuit issue as <a href="https://www.scmp.com/lifestyle/fashion-beauty/article/3179391/sports-illustrated-swimsuits-first-asian-plus-size-cover">a validating experience</a>. </p>
<p>Yet the swimsuit issue continues to promote sexual attractiveness as women’s main currency. As <a href="https://women-gender-equality.canada.ca/en.html">women fight to be taken seriously</a>, repeating this message <a href="https://www.forbes.com/2009/12/05/appearance-work-pay-forbes-woman-leadership-body-weight.html">is harmful</a>. </p>
<h2>Sex does sell</h2>
<p>When <a href="https://fitisafeministissue.com/2022/05/28/inclusive-objectification-anyone/">I wrote a blog post about this</a>, readers on <a href="https://www.facebook.com/feministfitness">the blog’s Facebook page</a> mostly agreed with me in comments writing: “yay, now us fat girls can be objectified too” and “even in ‘inclusivity’ the goal of the swimsuit issues is still policing feminine bodies.” </p>
<p>But some said “sex sells: get over it” and “where’s the harm?” Others argued my view throws a wet blanket over a beach party where finally (finally!) women of diverse shapes and sizes are not just welcome but considered sexy and beautiful. </p>
<p>Sex does sell and it’s too bad that the sexualization of women is a multi-billion dollar industry in which <a href="https://www.businessinsider.com/business-facts-about-the-sports-illustrated-swimsuit-issue-2013-2">the swimsuit issue trades</a>. </p>
<p>The swimsuit issue is a setback for women and models are engaging in what philosopher Shay Welch, in her book <a href="https://rowman.com/ISBN/9781498505413/Existential-Eroticism-A-Feminist-Approach-to-Understanding-Womens-Oppression-Perpetuating-Choices"><em>Existential Eroticism</em></a>, calls “oppression-perpetuating choices.” She defines “existential eroticism” as women’s oppression through beauty and sexuality.</p>
<p>Basically, some women’s choices contribute to conditions of oppression for women as a group even if we can understand why women make them.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/Ced0FcSgm3t","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>While we would be better off without the swimsuit issue (we’d be better off without lots of things), I’m not suggesting it be censored or banned. Nor is this an objection to the display of bodies, even skimpily clad bodies. But is there a different way of going about it? </p>
<p>Look to <em>ESPN</em>’s <a href="https://www.espn.com/espn/feature/story/_/id/27400369/the-body-issue">The Body Issue</a>, which depicts a diversity of athletes (not only women and not only non-disabled), nude and often in action shots that display their athleticism within their chosen sport. </p>
<p>It presents a completely different esthetic of physicality, based in athleticism. Athleticism isn’t the only dimension along which to appreciate bodies, but it’s not clear how the swimsuit issue, the very essence of which is to represent a particular type of sexualized bodies, could morph into something that celebrates the body in a different way. </p>
<p>Swimsuit issue editor-in-chief <a href="https://swimsuit.si.com/swimnews/sports-illustrated-swimsuit-2022-cover-models-kim-kardashian-ciara-maye-musk-yumi-nu">MJ Day says</a>, “We encourage readers to see these models as we see them — multifaceted, multitalented and sexy while they’re at it.” As multi-dimensional as these women may be, their suitability for the swimsuit issue ultimately depends on being sexy. </p>
<p>We should be wary of uncritically accepting the sexual objectification of women for the sake of inclusion and diversity. When we do, we’re celebrating the swimsuit issue as something empowering for women and praising it for “breaking barriers.” Given its context and target-audience — straight, cisgender men — doing so perpetuates the pernicious idea that women (all women) need to be sexy-to-men to be acceptable. </p>
<p>We can promote inclusion and celebrate the beauty of diverse bodies without piggybacking on that relentless message about what makes women worthy.</p><img src="https://counter.theconversation.com/content/184211/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tracy Isaacs is affiliated with the blog Fit Is a Feminist Issue as co-founder and regular contributor. The blog is not-for-profit, ad-free, and generates no revenue.</span></em></p>We can promote inclusion and celebrate the beauty of diverse bodies without piggybacking on that relentless message about what makes women worthy.Tracy Isaacs, Professor (Philosophy), Western UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1834262022-05-19T09:42:11Z2022-05-19T09:42:11ZReducing COVID transmission by 20% could save 2,000 Australian lives this year<p>Australia’s <a href="https://www.health.gov.au/sites/default/files/documents/2022/05/coronavirus-covid-19-at-a-glance-9-may-2022.pdf">COVID death toll</a> is rising, yet public health measures to reduce transmission such as mask mandates are largely a thing of the past. </p>
<p>It’s time for governments and the community to consider what measures can be reintroduced to reduce COVID transmission and deaths, particularly during waves of infection. </p>
<p>Cutting COVID transmission by 20% could avert more than one million infections and 500 COVID deaths in Victoria this year, our new modelling shows. </p>
<p>Given Victoria makes up around 25% of Australia’s population, if extrapolated, these results suggest a 20% reduction in transmission could save up to 2,000 lives nationally.</p>
<p>Even if reintroducing public health measures cut COVID transmission by 10%, this could save between 198 and 314 Victorian lives between now and the end of 2022. Again, this would translate to many more lives saved nationally.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/covid-has-killed-5-600-australians-this-year-and-the-pandemic-isnt-over-ethics-can-shape-our-response-182765">COVID has killed 5,600 Australians this year and the pandemic isn't over. Ethics can shape our response</a>
</strong>
</em>
</p>
<hr>
<h2>COVID isn’t ‘just like the flu’</h2>
<p>The prevailing view in Australia is we can now treat COVID “like the flu”. However, the dramatic and sustained increase in COVID-related deaths in 2022 tells a very different story. There have been <a href="https://www.health.gov.au/sites/default/files/documents/2022/05/coronavirus-covid-19-at-a-glance-9-may-2022.pdf">5,687 COVID deaths reported</a> in Australia since January 1.</p>
<p>During the Omicron wave in January 2022, COVID was the second most common cause of death nationwide, with <a href="https://www.abs.gov.au/statistics/health/causes-death/provisional-mortality-statistics/latest-release">2,865 more people dying</a> in that month than is normally expected. That’s a 22% increase. </p>
<p>Critically, COVID deaths have not stopped since the January peak: our current <a href="https://www.covid19data.com.au/deaths">seven-day average</a> sits at about 45 deaths per day, or 315 deaths each week. </p>
<p>In comparison, our most recent severe influenza season (2017) caused <a href="https://www.abs.gov.au/ausstats/abs@.nsf/Lookup/by%20Subject/3303.0%7E2017%7EMain%20Features%7EDeaths%20due%20to%20influenza%7E5">1,255 deaths</a> across the entire year.</p>
<h2>We have vaccines, so why are there so many deaths?</h2>
<p>There are still so many deaths because we have let the virus run. By scaling back public health measures and delivering an “it’s over” message, we have allowed almost unfettered transmission. </p>
<p>Currently, <a href="https://www.health.gov.au/sites/default/files/documents/2022/05/coronavirus-covid-19-at-a-glance-18-may-2022.pdf">381,000 Australians</a> are known to be infected with SARS-CoV-2, the virus that causes COVID. With high case numbers comes a high death toll, even with a reduced case fatality rate (the proportion of those infected who die).</p>
<p>This relaxed policy stance – combined with emerging variants (three new Omicron strains have entered Australia), winter encouraging more time indoors, and waning immunity – suggest high caseloads will continue for some time yet.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1522441592266964992"}"></div></p>
<h2>Who is dying of COVID?</h2>
<p>In order to reduce COVID deaths, it’s important to understand who is dying and why. While some basic information on deaths is available for some states, additional data – for example, whether those who die are eligible for antiviral treatment – is needed. Such data could enable targeted public health action such as improving treatment access. </p>
<p>Nevertheless, with the data we have we know older people continue to be at greatest risk. Last week in NSW, <a href="https://www.health.nsw.gov.au/Infectious/covid-19/Documents/weekly-covid-overview-20220514.pdf">41% of all COVID deaths</a> were in aged care residents, despite very high rates of vaccination. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/australia-is-failing-marginalised-people-and-it-shows-in-covid-death-rates-177224">Australia is failing marginalised people, and it shows in COVID death rates</a>
</strong>
</em>
</p>
<hr>
<p>We often hear those who die from COVID have pre-existing medical conditions. This is true – <a href="https://www.abs.gov.au/articles/covid-19-mortality-australia-deaths-registered-31-january-2022#deaths-due-to-covid-19-associated-causes-of-death">about 70% of deaths</a> due to COVID were in people with chronic conditions.</p>
<p>But note that <a href="https://www.aihw.gov.au/reports/australias-health/chronic-conditions-and-multimorbidity">half of all Australians</a> have a chronic condition, as do 80% of those aged 65 and older. Given most of those who have died due to COVID are aged over 65, it’s not surprising most also have an underlying condition.</p>
<h2>Are people dying ‘with’ rather than ‘of’ COVID?</h2>
<p><a href="https://www.theguardian.com/australia-news/2022/may/18/pm-dismisses-need-for-more-measures-to-limit-covid-deaths-suggests-australians-dying-with-not-of-the-virus">Some argue</a> the high rates of COVID deaths isn’t as worrying as it seems because people are dying “with” COVID rather than “from” COVID. </p>
<p>But the majority (89.8%) of <a href="https://www.abs.gov.au/articles/covid-19-mortality-australia-deaths-registered-until-30-april-2022">COVID deaths</a> are “from” COVID. </p>
<p>For those defined as dying “with” COVID, this means COVID has possibly or probably “contributed” to those deaths. </p>
<p>For example, a person is infected with COVID which weakens their immune system and leads to a bloodstream infection (sepsis). They’re hospitalised and die three weeks after their COVID diagnosis. Although their death is directly “due to” sepsis, it is also “with” COVID because COVID caused the decline in their health which ultimately led to their death. COVID is not incidental in these deaths.</p>
<p>COVID is also killing young people – even children. Eight children aged nine and under have <a href="https://www.health.gov.au/health-alerts/covid-19/case-numbers-and-statistics#cases-and-deaths-by-age-and-sex">died in Australia from COVID</a> since the pandemic began, as well as five people aged ten to 19 years, 22 in their twenties, and 65 in their thirties. </p>
<p>It’s impossible to know if COVID will cause significant numbers of premature death in coming years. Given the damage the SARS-CoV-2 virus causes to the heart, brain, kidneys and lungs, we have reason enough to be seriously concerned. </p>
<h2>What could reduce the COVID death toll?</h2>
<p>Vaccination continues to be hugely important, and the main reason we can even contemplate our current open lifestyle. But vaccination alone is not enough. </p>
<p>Improving air quality and/or wearing a high-quality N95/P2 mask in indoor spaces cause minimal disruption to the community but interrupt COVID transmission effectively. </p>
<p>To illustrate the benefit of interventions, we used <a href="https://www.burnet.edu.au/covid-19/129_modelling">our model</a> to simulate three hypothetical scenarios for the state of Victoria for the remainder of 2022. </p>
<p>We first modelled a scenario with no additional interventions (the light blue line). We compared this with two scenarios where, from May 20, hypothetical interventions were introduced that could reduce the risk of transmission per contact by 10% (the dark blue line) or 20% (the red line). </p>
<p>We didn’t specify which specific interventions should be adopted to make up the 10% or 20% reduction. It could be a single intervention a or combination that make up the 10% to 20% reduction. </p>
<p>Between May 20 and the end of 2022, the outcomes from the “no additional intervention” scenario were an extra 2.22-2.38 million infections or reinfections and 1,060-1,450 deaths in Victoria. </p>
<p>With interventions reducing transmission by 10%, 596,000-614,000 infections and 198–314 deaths could be averted (a 16-25% reduction) over this period.</p>
<p>With interventions reducing transmission by 20%, 1.08-1.10 million infections and 462-502 deaths could be averted (a 37-40% reduction). As outlined above, this translates to up to 2000 lives nationally.</p>
<p>These are likely to underestimate the impact of interventions because the analysis was deliberately conservative and didn’t consider new COVID variants or sub-variants (only omicron BA.1 and BA.2). </p>
<p>The simple message is a small reduction in transmission has a big impact on mortality.</p>
<h2>How do we do this modelling?</h2>
<p>The model used for this work was <a href="https://github.com/institutefordiseasemodeling/covasim">COVASIM</a>, a model that can assess the impact of different policies and behaviours on COVID transmission, hospitalisations and deaths. The model has been used to assist policy decisions in Australia, the United States and the United Kingdom. </p>
<p>People in the model are assigned an age (which affects their susceptibility to infection and their disease prognosis), a household, a school (for people aged five to 17) or a workplace (for people over 18, up to 65), and they participate in a number of community activities that may include attending restaurants, pubs, places of worship, community sport, and social gatherings. </p>
<p>The model includes:</p>
<ul>
<li>vaccination (including individual dosing schedules, vaccine types and waning immunity)</li>
<li>testing (PCR or rapid antigen tests)</li>
<li>contact tracing (self-tracing)</li>
<li>quarantine of close contacts</li>
<li>isolation of confirmed cases</li>
<li>masks</li>
<li>a variety of policy restrictions to prevent or reduce transmission in different settings (such as closing schools or workplaces, density limits in hospitality and retail settings, restrictions on social gathering sizes).</li>
</ul>
<figure class="align-center ">
<img alt="Woman in a mask shops for clothes." src="https://images.theconversation.com/files/464178/original/file-20220519-25-t0w2ie.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464178/original/file-20220519-25-t0w2ie.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464178/original/file-20220519-25-t0w2ie.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464178/original/file-20220519-25-t0w2ie.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464178/original/file-20220519-25-t0w2ie.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464178/original/file-20220519-25-t0w2ie.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464178/original/file-20220519-25-t0w2ie.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The COVASIM model assesses the impact of different policies on behaviours and COVID transmission.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/">Shutterstock</a></span>
</figcaption>
</figure>
<h2>It’s not just about the economy</h2>
<p>Australia successfully mitigated the direct impact of COVID in the first two years of the pandemic. However, recently Australia has made little effort to reduce the impact of COVID. We are quietly, perhaps unknowingly, approving a trade-off between COVID deaths, and economic and social well-being more generally. </p>
<p>Many people seem unaware of the high death numbers, and that simple interventions can make a meaningful difference. </p>
<p>But the value of the current trade-off is unclear. The economic and social benefits of winding back key public health measures, when tens of thousands of COVID cases occur each day, have not been established. Indeed, stories of major COVID-driven disruption are common, suggesting the opposite is true. </p>
<p>Australia must find a middle road, centred around slowing transmission, reinvigorating vaccine roll-out and scaling-up treatment options for people with COVID infections. Otherwise, 10,000 or more COVID deaths per year could well be our new – previously unthinkable – normal.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/im-at-home-with-covid-when-do-i-need-to-see-a-doctor-and-what-treatments-are-available-176884">I’m at home with COVID. When do I need to see a doctor? And what treatments are available?</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/183426/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Margaret Hellard has received funding receives funding from the Victorian Government, the Federal Government, the New South Wales Government, the Macquarie Foundation and the Minderoo Foundation for COVID-19 related research. None provided support for this specific work. She also receives funding from the National Health and Medical Research Council of Australia for other research, and Gilead Science and Abbvie for investigator initiated non COVID-19 related research.
</span></em></p><p class="fine-print"><em><span>Brendan Crabb and the Institute he leads receives research grant funding from the National Health & Medical Research Council of Australia, & other Australian federal and Victorian State Government bodies.</span></em></p><p class="fine-print"><em><span>Dominic Delport has received funding from the NSW government in 2021 and continues to receive funding from the Victorian government for COVID-19 modelling work.</span></em></p><p class="fine-print"><em><span>Nick Scott receives funding from the Victorian Government for COVID-19 related work, and has previously received funding from the New South Wales Government and Federal Government for COVID-19 related work. No government funding was received for this specific work. He also receives funding from the National Health and Medical Research Council of Australia for research on other diseases. </span></em></p>We modelled the impact small reductions in transmission would have on COVID deaths. We found a 20% drop could save the lives of 500 Victorians this year, or 2,000 people nationally.Margaret Hellard, Deputy Director (Programs), Burnet InstituteBrendan Crabb, Director and CEO, Burnet InstituteDominic Delport, Health modeller, Burnet InstituteNick Scott, Econometrician, Burnet InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1745332022-01-13T19:11:27Z2022-01-13T19:11:27ZWhen will this COVID wave be over? 4 numbers to keep an eye on and why<figure><img src="https://images.theconversation.com/files/440576/original/file-20220113-21-oo9qbk.jpg?ixlib=rb-1.1.0&rect=0%2C2%2C1000%2C603&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/pandemic-second-wave-coronavirus-outbreak-covid-1760999612">Shutterstock</a></span></figcaption></figure><p>Before Australia’s <a href="https://www.health.gov.au/health-alerts/covid-19/testing">recent changes to COVID testing</a>, working out when we reached the peak of cases was, in principal, straightforward. </p>
<p>We looked at the numbers of new daily cases, diagnosed via PCR. From there, we worked out a range of other key indicators related to COVID spread, testing and hospitalisation – each dependent on those daily case numbers.</p>
<p>However, we’ve seen a huge spike in cases recently as people test positive using rapid antigen tests, especially as <a href="https://www.service.nsw.gov.au/transaction/register-positive-rapid-antigen-test-result">reporting their results</a> to state health authorities is now possible and becoming mandatory.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1481335826244341761"}"></div></p>
<p>So it will be a few days before we can measure some key numbers with any degree of accuracy. Only then will be able to say with confidence when we’ve hit the peak and are coming down the other side.</p>
<h2>1. The number of new daily cases</h2>
<p>Most people by now would have seen an epidemic curve. It is a plot of the number of new cases of COVID-19 diagnosed each day. Here is the current epidemic curve for New South Wales.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/440582/original/file-20220113-17-y0jkyp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440582/original/file-20220113-17-y0jkyp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440582/original/file-20220113-17-y0jkyp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440582/original/file-20220113-17-y0jkyp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440582/original/file-20220113-17-y0jkyp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=453&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440582/original/file-20220113-17-y0jkyp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=453&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440582/original/file-20220113-17-y0jkyp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=453&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Epidemic curve for NSW. Note the erratic case numbers in recent days.</span>
<span class="attribution"><span class="source">Author provided/Adrian Esterman</span></span>
</figcaption>
</figure>
<p>As for the date, states and territories use different cut-off times for defining a 24-hour period. As authorities undertake investigations, the date of some cases can change. So, do we plot the daily announced case numbers, or the “true” case number after modifications?</p>
<p>That sounds complicated, but even more complicated is trying to define a case. </p>
<p>Before rapid antigen tests became <a href="https://www.tga.gov.au/covid-19-rapid-antigen-self-tests-are-approved-australia">available to the public</a> for use at home, cases were diagnosed from <a href="https://www.bmj.com/content/bmj/369/bmj.m1808.full.pdf">positive PCR tests</a>.</p>
<p>Then, because of <a href="https://www.news.com.au/national/testing-centres-across-the-country-under-pressure-as-omicron-wreaks-havoc/news-story/21f327ed42cc6141eb89286f1ef2b32f">huge queues</a> at PCR testing hubs and many people, even those with symptoms, giving up and not getting tested, our testing system changed.</p>
<p><a href="https://www.9news.com.au/national/coronavirus-update-national-cabinet-rapid-antigen-tests-changes-to-pcr-testing/45e11a40-4bbf-4a43-a2fb-5f7bdc7e3d33">National Cabinet agreed</a> to remove the requirement for a PCR test to confirm a positive <a href="https://www.tga.gov.au/covid-19-rapid-antigen-self-tests-are-approved-australia">rapid antigen test</a> result.</p>
<p>As most states and territories move towards reporting both positive PCR tests and positive rapid antigen tests, we still need to iron out the bumps in the data. Potentially, someone could get both tests and be included twice!</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1481385817667149824"}"></div></p>
<p>The uncertainty in case numbers also affects other key parameters we use to monitor the current wave.</p>
<h2>2. The Reff</h2>
<p>The effective reproduction number (Reff) is a measure of how many other people on average each case infects. We want that to get below 1 to stop an outbreak. At its most simple, the Reff is today’s case number, divided by the case number four days ago. </p>
<p>Since we currently have so many problems defining and counting case numbers, it will be a few days before we can consistently interpret the Reff for each state and territory again.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-are-the-symptoms-of-omicron-174476">What are the symptoms of omicron?</a>
</strong>
</em>
</p>
<hr>
<h2>3. Percentage of positive tests</h2>
<p>This is the percentage of positive tests out of all COVID-19 tests taken. It is an important measure as it gives an indication of the amount of undiagnosed cases in the community. </p>
<p>The <a href="https://apps.who.int/iris/bitstream/handle/10665/332073/WHO-2019-nCoV-Adjusting_PH_measures-Criteria-2020.1-eng.pdf?sequence=1&isAllowed=y">World Health Organization</a> suggests if it is under 5%, things are under control. </p>
<p>When diagnosis was only by PCR test, we had good data on both the number of tests, and the number that were positive. </p>
<p>Now, states and territories are moving to reporting rapid antigen test results, it’s not so straightforward.</p>
<p>Some jurisdictions like <a href="https://www.qld.gov.au/rat-positive/rapid-antigen-test-registration">Queensland</a> only ask you to report a positive result. This means we no longer know how many tests were taken. SA Health is encouraging people to <a href="https://www.sahealth.sa.gov.au/wps/wcm/connect/public+content/sa+health+internet/conditions/infectious+diseases/covid-19/testing+and+tracing/rapid+antigen+testing+rat+for+covid-19">report</a> negative tests as well, which is a much better system.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1462550205698428929"}"></div></p>
<h2>4. Number hospitalised</h2>
<p>As Australia opens up, we’ve been told to pay more attention to COVID-19 hospitalisations, rather than just the case numbers. But even that gets complicated.</p>
<p>Clearly if someone tests positive for COVID-19 and then gets admitted to hospital, they are an admitted case. But what if they are admitted as a probable case? </p>
<p>And should hospitalisation numbers include people being managed in a <a href="https://theconversation.com/what-is-hospital-in-the-home-and-when-is-it-used-an-expert-explains-167359">hospital-in-the-home</a> type arrangement? After all, they still take up hospital resources.</p>
<p>Finally, what if they were admitted for something else but subsequently diagnosed with COVID-19 in hospital? </p>
<p>Even more difficult is attempting to calculate the <em>rate</em> of COVID-19 hospitalisation. This is the number of people in hospital with COVID-19 divided by the number of people diagnosed. But you have to decide which time periods you’re talking about, another debate entirely.</p>
<p>There are similar issues with measuring the number and rates of people in intensive care.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/were-seeing-more-covid-patients-in-icu-as-case-numbers-rise-that-affects-the-whole-hospital-165966">We're seeing more COVID patients in ICU as case numbers rise. That affects the whole hospital</a>
</strong>
</em>
</p>
<hr>
<h2>How do these changes impact modelling?</h2>
<p>NSW Health <a href="https://www.afr.com/policy/health-and-education/nsw-faces-restrictions-as-cases-surge-20220107-p59mka">recently</a> <a href="https://www.health.nsw.gov.au/Infectious/covid-19/Documents/icu-predictions.pdf">released modelling</a> to look at what’s ahead.</p>
<p>With current restrictions in place in NSW, the modelling shows a peak of 4,700 hospitalisations, with 273 in intensive care over mid- to late January.</p>
<p>It is unclear whether changes to testing rules have been factored into the modelling. However, it’s understood, even if the detection rate changes significantly, it doesn’t affect any projection of when the peak will be reached that much.</p>
<p>Modelling is therefore still likely to be reasonably accurate despite the changes to COVID testing. This is good news for other states and territories that rely on modelling results for planning. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/scientific-modelling-is-steering-our-response-to-coronavirus-but-what-is-scientific-modelling-135938">Scientific modelling is steering our response to coronavirus. But what is scientific modelling?</a>
</strong>
</em>
</p>
<hr>
<h2>Where to from here?</h2>
<p>A good start would be to have mandatory reporting of rapid antigen test results, both positive and negative. That way we can calculate the percentage of positive tests again. </p>
<p>The United Kingdom has a good system. After you take a rapid antigen test there, you <a href="https://www.gov.uk/report-covid19-result">scan a QR code</a> on the pack and report the test results as positive, negative or void to a central government database. </p>
<p>Importantly, let’s have one national body responsible for defining, collecting and reporting COVID-19 statistics. It could be the <a href="https://www.aihw.gov.au">Australian Institute of Health and Welfare</a>. Better still would be to have our own Centre for Disease Control, which people like myself have been <a href="https://theconversation.com/coronavirus-pandemic-shows-its-time-for-an-australian-centre-for-disease-control-in-darwin-138724">calling for</a> for a long time.</p>
<p><em><a href="https://twitter.com/Chrisbilbo">Chris Billington</a>, from the University of Melbourne, contributed to the section on modelling.</em></p><img src="https://counter.theconversation.com/content/174533/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adrian Esterman does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>We’d all like some answers. But uncertainty over how we count COVID cases is complicating the picture. Here’s what to expect in the days and weeks ahead.Adrian Esterman, Professor of Biostatistics and Epidemiology, University of South AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1716562021-11-17T19:03:59Z2021-11-17T19:03:59ZUS vaccine rollout was close to optimal at reducing deaths and infections, according to a model comparing 17.5 million alternative approaches<figure><img src="https://images.theconversation.com/files/432253/original/file-20211116-19-opv49.jpg?ixlib=rb-1.1.0&rect=0%2C83%2C5054%2C3094&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In the U.S., people were placed into four groups for vaccine access.</span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/VirusOutbreakFlorida/4458ecb3aa344896a73bac36a61cc7aa/photo?Query=vaccination%20eligible&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=328&currentItemNo=172">AP Photo/Lynne Sladky</a></span></figcaption></figure><p><em>The <a href="https://theconversation.com/us/topics/research-brief-83231">Research Brief</a> is a short take about interesting academic work.</em></p>
<h2>The big idea</h2>
<p>The Centers for Disease Control and Prevention’s plan for who gets vaccines and in what order <a href="https://doi.org/10.1371/journal.pone.0259700">saved nearly as many lives and prevented nearly as many infections</a> as a theoretically perfect rollout, according to a new mathematical model we developed to assess the rollout of COVID–19 inoculations in the U.S.</p>
<p>In December 2020, with a limited number of vaccines available, the CDC had to make a hard decision: Who gets the COVID-19 vaccines first? It decided to <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm695152e2.htm">divide the U.S. population into four groups</a> for vaccine prioritization based on age, occupation, living condition and known COVID-19 risk factors.</p>
<p>Using a new model and an Iowa State University supercomputer, we compared the real–world CDC recommendations with 17.5 million possible strategies that also staggered the rollout in up to four phases. To calculate how well a vaccine allocation strategy performed, our model measured total deaths, cases, infections and years of life lost.</p>
<p>We found that the CDC allocation strategy performed exceptionally well – <a href="https://doi.org/10.1371/journal.pone.0259700">within 4% of perfect</a> – in all four measures.</p>
<p>According to our model, the <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm695152e2.htm">CDC’s decisions</a> to not vaccinate children initially and prioritize health care and other essential workers over nonessential workers were both correct. But our model also showed that giving individuals with known risk factors earlier access to vaccines would have led to slightly better outcomes.</p>
<p>No single rollout was able to simultaneously minimize deaths, cases, infections and years of life lost. For example, the strategy that minimized deaths led to a higher number of cases. Given these limitations, the CDC plan did a good job of balancing the four goals of vaccination and was particularly good at reducing deaths.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1362071405668499456"}"></div></p>
<h2>Why it matters</h2>
<p><a href="https://doi.org/10.1126/sciadv.abf1374">Many other studies</a> have looked at <a href="https://doi.org/10.1126/science.abe6959">a small number of alternative COVID-19 vaccine rollouts</a>. Our project incorporated more characteristics of the current pandemic and considered 17.5 million possible strategies. We believe this gives our results more authority.</p>
<p>Our model includes <a href="https://doi.org/10.1038/s41591-020-0962-9">differences in disease severity and susceptibility</a> to the coronavirus due to age. It also incorporates social distancing levels that change over time, as well as <a href="https://doi.org/10.1016/j.lanepe.2021.100252">variable infectivity rates</a> to account for more contagious virus strains such as the delta variant.</p>
<p>All this gave us the ability to accurately assess the CDC’s past decisions. But the greater value of our modeling approach lies in how it could help guide future policy.</p>
<p>By changing model inputs, we were able to show how optimal rollout strategies should change given different <a href="https://doi.org/10.1038/s41598-021-00794-6">vaccine hesitancy rates</a> and for different vaccines that can <a href="https://doi.org/10.1038/s41591-021-01410-w">protect in different ways against infection or death</a>. For countries that are <a href="https://graphics.reuters.com/world-coronavirus-tracker-and-maps/vaccination-rollout-and-access/">currently planning COVID-19 vaccination strategies</a>, our model could help decision-makers develop the most effective strategies given their local resources and specifics. And even in the U.S., our modeling technique can inform allocation strategies for booster shots and future vaccine rollouts so health care administrators can make the best use of limited resources.</p>
<h2>What still isn’t known</h2>
<p>Any model is a simplification of reality. Our model did not account for <a href="https://doi.org/10.1136/bmj.n99">re-infections</a> or <a href="https://dx.doi.org/10.1016%2Fj.socscimed.2020.113638">varying levels of vaccine hesitancy</a> based on socio-economic status, political ideology or race. We also assumed that the level of hesitancy was constant over time.</p>
<p>Additionally, some important factors for how the coronavirus spreads – like <a href="https://doi.org/10.1371/journal.pmed.0050074">contact rates between individuals of different age and demographic groups</a> and <a href="https://www.cdc.gov/coronavirus/2019-ncov/hcp/planning-scenarios.html">the contagiousness of asymptomatic</a> and vaccinated individuals – are still unknown. Better data on these parameters would improve the accuracy of our results.</p>
<h2>What’s next</h2>
<p>Now that we have the model built, we can extend it. For example, we can study how <a href="https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/vaccine-induced-immunity.html">waning immunity</a> and booster shots might affect the spread of the disease. Our computer code is <a href="https://github.com/ckadelka/COVID19-CDC-allocation-evaluation">available to the public</a>, and we hope it will guide health care policymakers in the U.S. and around the world.</p><img src="https://counter.theconversation.com/content/171656/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>With limited vaccines available in early 2021, the CDC had to decide which people received vaccines first. With the help of a supercomputer, researchers have shown that the CDC did an excellent job.Audrey L. McCombs, PhD. Candidate in Ecology and Statistics, Iowa State UniversityClaus Kadelka, Assistant Professor of Mathematics, Iowa State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1680882021-10-01T02:33:58Z2021-10-01T02:33:58ZHow COVID health advice and modelling has been opaque, slow to change and politicised in Australia<p>In a recent article, The Australian’s health reporter <a href="https://www.theaustralian.com.au/science/modelling-road-maps-vary-wildly-as-covid19-keeps-us-guessing/news-story/1c559ae4685b8e65c7a7ca1c55d9858d">asked</a>: “has any modelling put forward by scientific institutes throughout the pandemic ever proved accurate?”</p>
<p>It’s a good question but the answer lies in understanding the truth about modelling — it cannot predict the future.</p>
<p>Rather, it’s a process that identifies variables most likely to shape the course of, say, a pandemic and to quantify their impacts over time.</p>
<p>Politicians commission modellers to assess the present state of things then consider what might happen if various policy settings were to be adjusted.</p>
<p>By providing assessments of the costs, benefits and impacts of proposed policies, good modelling provides governments with a firm foundation for deciding which policies will have what effects.</p>
<p>Politicians know invoking “health modelling” generates public support for their policies.</p>
<p>This week, federal Treasurer Josh Frydenberg claimed his <a href="https://www.news.com.au/finance/work/covid19-disaster-payments-to-be-phased-down-in-october-scrapped-in-november/news-story/cb5fa9e695272f2aed65335c2eeb6ec4">decision to scrap COVID support payments</a> at 80% double-dosed vaccination coverage accorded with the National Plan as informed by the Doherty Institute modelling.</p>
<p>But in neither the plan nor the modelling is any connection drawn between ending support payments at any level of vaccination coverage.</p>
<p>Nor was any modelling apparently commissioned on the likely impact of removing financial support for the most vulnerable when infection rates are high – as in Sydney – and rising alarmingly as in Melbourne.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/scientific-modelling-is-steering-our-response-to-coronavirus-but-what-is-scientific-modelling-135938">Scientific modelling is steering our response to coronavirus. But what is scientific modelling?</a>
</strong>
</em>
</p>
<hr>
<h2>The power of ‘health advice’</h2>
<p>Since the beginning of the COVID pandemic, politicians have justified the many difficult decisions they’ve had to make as being based on “health advice”.</p>
<p>As it should be, “health advice” provided to politicians by chief health officers is informed by modelling commissioned from a range of well-respected and credentialed scientific research institutes.</p>
<p>The public draws a strong causal link between health modelling inputs and policy outcomes.</p>
<p>They are more likely to accept policies buttressed by modelling and health advice than not.</p>
<p>Modelling is therefore a powerful political tool.</p>
<p>In a pandemic, political decisions have human and economic impacts that are irrevocable, significant and for many a matter of life and death. </p>
<p>Even more reason, therefore, for the scientific integrity of modelling that informs those decisions to be beyond reproach.</p>
<p>The brief given to the modellers is critically important in setting parameters and assumptions and selecting the variables that will be assessed and measured.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1429944359164604423"}"></div></p>
<h2>Transparency is essential</h2>
<p>The key to building public trust in modelling is full transparency.</p>
<p>But in Australia, these briefs and processes are often shrouded and opaque. Secrecy and a lack of transparency has greatly affected the quality of Australia’s response to COVID.</p>
<p>At the beginning of the pandemic, the federal government’s <a href="https://www.health.gov.au/resources/publications/australian-health-sector-emergency-response-plan-for-novel-coronavirus-covid-19">Emergency Response Plan for Novel Coronavirus</a> did not canvass the cessation of international travel and closure of borders, <a href="https://www1.racgp.org.au/newsgp/clinical/thousands-of-doctors-call-for-lockdown">domestic lockdowns</a> and the <a href="https://www.theguardian.com/australia-news/2020/jul/22/australias-about-face-on-masks-and-covid-19-why-our-health-advice-was-late-to-the-party">use of masks</a> as possible or desirable responses to the pandemic.</p>
<p>Yet within weeks of this advice being published, the modelling had been overtaken by events.</p>
<p>Travel from some but not all countries was stopped, international and domestic borders closed from late March 2020, and lockdowns implemented across Australia.</p>
<p>In the initial planning and options, lockdowns, cessation of travel and masks were not among the assumptions. The entire response was based on a paradigm of influenza rather than the facts of coronavirus and need for rapid, preventive responses.</p>
<p>The assumptions informing the initial modelling should have been published, interrogated and debated before, and not after, the initial and ineffectual policy settings were adopted.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/australias-covid-plan-was-designed-before-we-knew-how-delta-would-hit-us-we-need-more-flexibility-168189">Australia's COVID plan was designed before we knew how Delta would hit us. We need more flexibility</a>
</strong>
</em>
</p>
<hr>
<h2>Separating science from politics</h2>
<p>Over the course of the pandemic, the assumptions of modelling commissioned by governments should have been published, scrutinised and debated before, not after, the modelling was undertaken.</p>
<p>Modelling ought to have been commissioned from a range of Australia’s excellent scientific institutions.</p>
<p>Open debate might have meant aerosol transmission of first Alpha and then Delta would have been factored into projections and policy-making about the efficacy of hotel quarantine and border protection far earlier than it was.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1397696110177574919"}"></div></p>
<p>This unnecessary addiction to secrecy has eroded the trust and confidence that should exist between governments and the people.</p>
<p>Politics and science each have their separate and distinct roles to play in the managing the pandemic and reducing to the lowest possible levels the damage it causes to lives and livelihoods.</p>
<p><a href="https://www.openforum.com.au/australias-response-to-the-hivaids-crisis/">In the response to HIV/AIDS</a>, the politicians of the day ensured scientific advice was provided independently of governments and published as it became available.</p>
<p>The advice became the foundation of the political decision-making process.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1436091307965902854"}"></div></p>
<p>Now, as then, Australians expect a similar standard of open and independent scientific advice, information and assessment about the present and likely impact of the pandemic.</p>
<p>Whether commissioned by governments or acting independently, Australia’s pandemic modellers have lived up to their responsibilities to science and the Australian people.</p>
<p>They have applied their expertise to quantifying COVID and the costs and benefits of policy options.</p>
<p>But the critical decisions on assumptions, debate, contestability and transparency are made by politicians, not modellers.</p>
<p>As much as some politicians may wish to deny it, they alone are responsible and accountable to the Australian people for the decisions that have created Australia’s COVID response and will shape its future.</p>
<p>Modelling is integral to building the most robust, sustainable and well-supported response to the increasingly complex challenges of the pandemic.</p>
<p>The Australian people will be best served by separating science from politics.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-do-the-states-have-to-obey-the-covid-national-plan-167357">Explainer: do the states have to obey the COVID national plan?</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/168088/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>William Bowtell is affiliated with OzSage, in an unpaid and informal capacity.</span></em></p>The Australian people will be best served by separating science from politics.William Bowtell, Adjunct professor, Kirby Institute for Infection and Immunity, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1678772021-09-14T05:02:37Z2021-09-14T05:02:37ZNSW risks a second larger COVID peak by Christmas if it eases restrictions too quickly<p>New South Wales <a href="https://www.nsw.gov.au/media-releases/roadmap-to-freedom-unveiled-for-fully-vaccinated">plans to relax restrictions</a> when vaccination targets of 70% and 80% of those aged 16 years and over are met. </p>
<p>The national plan was based on the assumption there <a href="https://www.abc.net.au/news/2021-08-24/head-of-doherty-institute-covid19-nsw-vaccine-vic-scott-morrison/100401082">would be just 30 cases</a> when restrictions were lifted. However, NSW may have cases in the hundreds or thousands when restrictions are relaxed.</p>
<p>The current discussion has been around “the peak” occurring during current restrictions. </p>
<p>But <a href="https://www.ozsage.org/icu-modelling/">modelling</a> from my team at UNSW shows if current restrictions are relaxed while a large proportion of the community is unvaccinated, a larger, second peak may occur that may overwhelms our hospitals – unless countermeasures are taken to prevent that. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/flattening-the-covid-curve-3-weeks-of-tougher-lockdowns-in-sydneys-hotspots-halved-expected-case-numbers-167778">Flattening the COVID curve: 3 weeks of tougher lockdowns in Sydney's hotspots halved expected case numbers</a>
</strong>
</em>
</p>
<hr>
<h2>What would a second peak look like?</h2>
<p>The 70-80% adult vaccination targets correspond to 56-64% of the whole population, leaving plenty of room for the virus to spread among increasingly mobile people. </p>
<p>If the first relaxation of restrictions occurs around October 18, our modelling predicts a second, larger peak <a href="https://www.ozsage.org/media_releases/modelling-of-nsw-roadmap-to-freedom-icu-capacity-for-the-delta-epidemic-2021/">will occur</a> between December 24-29 2021. </p>
<p>If restrictions are only relaxed around November 6 when the 80% target is met, the peak occurs later, between January 6-12 2022 instead of around Christmas day. </p>
<p>The current strategy of mass vaccination is vital to our exit plan. But vaccination alone cannot control an epidemic that <a href="https://www.9news.com.au/national/coronavirus-australia-dead-last-in-oecd-for-vaccinated-people/51dbd565-25fe-4e07-891f-2c689c39c467">began</a> when fully vaccinated rates were extremely low. </p>
<p>This is because the virus spreads much faster (days) than the time taken to benefit from vaccine immunity after two doses (two months, with a six week interval between doses and two weeks after the second dose to get maximal immunity). </p>
<p>Also current vaccines are <a href="https://www.nejm.org/doi/10.1056/NEJMc2112981?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed">not as effective</a> against the Delta variant due to a combination of vaccine escape (meaning they’re not exactly matched to the Delta strain) and waning immunity. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-delta-defeating-us-heres-why-the-variant-makes-contact-tracing-so-much-harder-164780">Is Delta defeating us? Here's why the variant makes contact tracing so much harder</a>
</strong>
</em>
</p>
<hr>
<p>The restrictions used in NSW since the end of June have kept a lid on it, but case numbers have continued to grow. <a href="https://www.ozsage.org/icu-modelling/">We estimated</a> the 70% target may be met around October 18, and case numbers at that time may be in the thousands. </p>
<p>Depending on what steps accompany that relaxation, many different scenarios are possible. Modelling allows us to look at best and worst case scenarios and ensure the worst never occurs. </p>
<h2>Weighing the harms</h2>
<p>Controlling an epidemic is like balancing a set of old fashioned scales. Imagine the virus is a large, menacing metal weight sitting on one side, and the public health measures are a bunch of weights on the other, which are combined to keep the fight even.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/420996/original/file-20210914-21-kxhtjg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/420996/original/file-20210914-21-kxhtjg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=302&fit=crop&dpr=1 600w, https://images.theconversation.com/files/420996/original/file-20210914-21-kxhtjg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=302&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/420996/original/file-20210914-21-kxhtjg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=302&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/420996/original/file-20210914-21-kxhtjg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=379&fit=crop&dpr=1 754w, https://images.theconversation.com/files/420996/original/file-20210914-21-kxhtjg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=379&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/420996/original/file-20210914-21-kxhtjg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=379&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Modelling shows the effect of changes on either side of the scale.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/balance-between-diverse-objects-unequal-shapes-1385539847">Shutterstock</a></span>
</figcaption>
</figure>
<p>The Delta virus is very heavy, so we need many public health “weights” to keep it from winning. Vaccination alone is not enough, as we have seen in the United States, United Kingdom and Israel. </p>
<p>The public health “weights” include:</p>
<ul>
<li>vaccination </li>
<li>testing (identifying infected people and isolating them)</li>
<li>rapid contact tracing (within 24 hours of identifying an infected person)</li>
<li>restricting mixing and movement of people</li>
<li>masks</li>
<li>ventilation (safe indoor air).</li>
</ul>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/nWnOR3O-ZF0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">COVID-19 spreads through air.</span></figcaption>
</figure>
<p>Modelling can help us work out the effect of changes on either side of the scale. What if the epidemic is bigger? What if we remove movement restrictions? </p>
<p>That will tip the scales in favour of the virus, so we need to add more into the public health bowl to compensate for that removal. Maybe we can add more contact tracing, mask use or testing.</p>
<p>It’s a constant dance in trying to outwit the virus, and modelling helps by allowing to forecast the impact of different approaches to relaxing restrictions. </p>
<h2>Vaccination alone isn’t enough</h2>
<p>We already know that to relax restrictions, we need high vaccination rates. But because <a href="https://www.science.org/news/2021/08/grim-warning-israel-vaccination-blunts-does-not-defeat-delta">the vaccine is not enough against Delta</a>, at the 70-80% adult targets (which correspond to 56-65% of the whole population) there is still plenty of scope for the virus to spread. </p>
<p>COVID-19 will find under-vaccinated pockets and communities, whether it be disadvantaged urban communities or remote Aboriginal communities like <a href="https://www.abc.net.au/news/2021-08-26/covid-delta-unvaccinated-indigenous-communities-outbreak/100406682">Wilcannia</a>, which had a <a href="https://insightplus.mja.com.au/2021/34/vaccination-alone-not-enough-to-control-covid-19/">7% rate of full vaccination</a> when the Sydney outbreak arrived there. </p>
<p>So, our modelling shows that if you remove restrictions on movement, you need to add more weights to the public health bowl to stop the scales tipping in favour of the virus. This is the vaccine-plus and ventilation strategy recommended by <a href="https://www.ozsage.org/media_releases/september-2/">OzSAGE</a>, a new independent expert network I’m part of, which outlines a safe pandemic exit strategy. </p>
<p>It means when we open schools, we need to open classroom windows too, ensure clean air in classrooms, ensure parents and teachers are vaccinated, and have kids wearing masks. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/from-vaccination-to-ventilation-5-ways-to-keep-kids-safe-from-covid-when-schools-reopen-166734">From vaccination to ventilation: 5 ways to keep kids safe from COVID when schools reopen</a>
</strong>
</em>
</p>
<hr>
<p>We estimated the NSW capacity to rapidly trace contacts dropped off in mid-August. </p>
<p>So, in preparation of increasing mixing of people, we could <a href="https://www.thelancet.com/journals/landig/article/PIIS2589-7500(20)30251-X/fulltext">massively scale up</a> contact tracing capacity using digital methods. This would be adding more weight to the public health bowl. </p>
<p>We need to make sure testing capacity remains high and think about making rapid testing more widely available in schools, workplaces and homes.</p>
<p>We could also retain the outdoor mask mandate to ensure at least the protection of masks is not also reduced in the public health bowl (the current roadmap indicates outdoor mask mandates will be dropped). </p>
<h2>How bad could it get?</h2>
<p>We modelled six different scenarios and ways of adjusting the weights in the scales to ensure we do not overwhelm the health system. </p>
<p>We used the NSW definition of “<a href="https://www.news.com.au/lifestyle/health/health-problems/nsw-hospitals-preparing-to-move-to-code-black-as-covid19-icu-admissions-surge/news-story/74a3b87803f9416a72c30d42d646390a">code black</a>” – when there are not enough ICU beds and alternative models of care are needed. We used this to forecast scenarios that could cause or avoid code black conditions. </p>
<p>The <a href="https://www.ozsage.org/icu-modelling/">best case scenarios</a> would only have a single relaxing of restrictions and retain high mask use, scale up contact tracing, and retain some reduction of mixing between people. </p>
<p>On the other hand, relaxing restrictions progressively between the 70% and 80% targets, or drastically increasing mixing, while reducing mask use at the same time, and not improving contact tracing, will be taking too many weights out of the public health bowl. This would allow the virus to overwhelm the health system. </p>
<p>In the worst case scenario, there may be five weeks of code black conditions. In the best case scenario, code black is avoided. </p>
<p>If ICU care cannot be provided, the death rate will increase because all people who need ICU cannot receive it. So it’s essential we avoid code black conditions. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/were-two-frontline-covid-doctors-heres-what-we-see-as-case-numbers-rise-167195">We're two frontline COVID doctors. Here's what we see as case numbers rise</a>
</strong>
</em>
</p>
<hr>
<p>There are an infinite number of scenarios we could model, but the general trade-off between both sides of the scales are demonstrated by the model. </p>
<p>All models have uncertainty in them. Models predict a range of possibilities under different conditions, and worst-case scenarios usually do not eventuate, because authorities use the models to inform the prevention of severe scenarios. They may also reinstate restrictions if the health system is under threat. </p>
<p>Models are a valuable tool to guide and provide transparency to decision-making. At the moment, the choices in NSW are between “not great” and “terrible”. But that will change. </p>
<p>In time, we will have better vaccines (matched to Delta), boosters and higher vaccination rates in all Australians including children. These will add more weight to the public health side of the scales, and hopefully prevent the virus from winning.</p><img src="https://counter.theconversation.com/content/167877/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>C Raina MacIntyre receives funding from NHMRC, MRFF and is a member of OzSAGE, which is a voluntary, unpaid role.</span></em></p>An 80% adult vaccination rate corresponds to 64% of the overall population, leaving plenty of people susceptible to the virus if restrictions ease too quickly.C Raina MacIntyre, Professor of Global Biosecurity, NHMRC Principal Research Fellow, Head, Biosecurity Program, Kirby Institute, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1666592021-08-25T05:46:00Z2021-08-25T05:46:00ZOpening with 70% of adults vaccinated, the Doherty report predicts 1.5K deaths in 6 months. We need a revised plan<p>One consequence of the escalating COVID outbreak in New South Wales has been increased political tension around the “national plan” for COVID reopening. </p>
<p>The <a href="https://www.news.com.au/national/nsw-act/politics/pm-pushing-ahead-with-plan-to-reopen-at-70-per-cent-vaccination-rate/news-story/5549618adb0e4eea610ae71e3999125e">prime minister has argued</a> that states signed up to the plan – albeit “in principle”, whatever that means – and they should do whatever the plan says, whenever the plan says to do it. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1428651300242149381"}"></div></p>
<p><a href="https://thewest.com.au/opinion/peter-law/why-beyond-zero-covid-cases-is-a-puzzle-for-wa-and-why-there-are-no-easy-answers-moving-forward-ng-b881975852z">Some premiers are now pushing back</a>, arguing the Doherty Institute modelling was based on certain assumptions which no longer hold true so the previous agreement no longer stands. </p>
<p>There are three distinct questions at issue here. Is the Doherty Institute modelling still applicable? How does the national plan stack up? And what should happen next?</p>
<h2>1. Is the Doherty Institute modelling still applicable?</h2>
<p>The <a href="https://www.doherty.edu.au/uploads/content_doc/DohertyModelling_NationalPlan_and_Addendum_20210810.pdf">Doherty Institute was given a very specific remit</a>. It was asked “to define a target level of vaccine coverage for transition to Phase B of the national plan”, where lockdowns would be “less likely, but possible”. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/australia-has-a-new-four-phase-plan-for-a-return-to-normality-heres-what-we-know-so-far-163804">Australia has a new four-phase plan for a return to normality. Here's what we know so far</a>
</strong>
</em>
</p>
<hr>
<p>In identifying the vaccination coverage target for the transition to Phase B, Doherty’s experts assumed that testing, tracing, isolation, and quarantine (TTIQ), would be central to maintaining lower case numbers.</p>
<p>They highlighted two scenarios in terms of testing-tracing-isolation-quarantine capacity – an “optimal” scenario and a “partially effective” scenario – summarised in the table below.</p>
<p><strong>Doherty Institute modelling outcomes</strong></p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/417740/original/file-20210825-16-1ks9peb.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/417740/original/file-20210825-16-1ks9peb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/417740/original/file-20210825-16-1ks9peb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=179&fit=crop&dpr=1 600w, https://images.theconversation.com/files/417740/original/file-20210825-16-1ks9peb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=179&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/417740/original/file-20210825-16-1ks9peb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=179&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/417740/original/file-20210825-16-1ks9peb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=225&fit=crop&dpr=1 754w, https://images.theconversation.com/files/417740/original/file-20210825-16-1ks9peb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=225&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/417740/original/file-20210825-16-1ks9peb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=225&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">TTIQ = testing, tracing, isolation, and quarantine. This assumes an all adults vaccination allocation strategy.</span>
<span class="attribution"><span class="source">Doherty Institute</span></span>
</figcaption>
</figure>
<p>While these numbers may look acceptable, the assumptions underlying them are now hanging by a thread. </p>
<p><a href="https://www.health.gov.au/news/health-alerts/novel-coronavirus-2019-ncov-health-alert/coronavirus-covid-19-case-numbers-and-statistics#daily-reported-cases">Case numbers have been rising rapidly</a>, putting significant pressure on testing-tracing-isolation-quarantine capacity. </p>
<p>Doherty Institute described its assumptions thus:</p>
<blockquote>
<p>We assume that once community transmission becomes established leading to high caseloads, TTIQ [testing-tracing-isolation-quarantine] is less efficacious than the optimal levels observed in Australia because public health response capacity is finite.</p>
</blockquote>
<p>This tells us that given our current high case numbers, we can probably only assume, at best, “partially effective” testing-tracing-isolation-quarantine capacity. </p>
<p>It’s also important to note the Doherty modelling did not incorporate scenarios where the virus was in uncontrolled spread after target vaccination levels are achieved. </p>
<p>But it now seems unlikely that NSW – and maybe even Victoria – will be able to suppress COVID down to zero before any vaccination target is reached. </p>
<p>If lockdowns are eased according to the modelled targets, while there is still substantial community transmission, testing-tracing-isolation-quarantine is unlikely to be enough to suppress further spread sufficiently, potentially resulting in higher numbers of hospitalisations and deaths than initially modelled. </p>
<h2>2. How does the national plan stack-up?</h2>
<p>The federal government used the Doherty Institute report’s findings as the basis of the “<a href="https://www.pm.gov.au/sites/default/files/media/national-plan-to-transition-australias-national-covid-19-response-30-july-2021.pdf">national plan</a>” it put to National Cabinet. </p>
<p>But it glossed over the options, scenarios, and caveats in the Doherty modelling, and assumed the most optimistic testing-tracing-isolation-quarantine scenario: that everything would be rosy if Australia started opening up once 70% of adults (equivalent to only just over half the population) are vaccinated. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/national-cabinets-plan-out-of-covid-aims-too-low-on-vaccinations-and-leaves-crucial-questions-unanswered-165447">National Cabinet's plan out of COVID aims too low on vaccinations and leaves crucial questions unanswered</a>
</strong>
</em>
</p>
<hr>
<p>The transition to Phase C, where lockdowns would be targeted and vaccinated people would be exempt from restrictions, was also optimistically adopted at 80% adult vaccination, despite the lack of modelling for this scenario in the Doherty report.</p>
<p>In a bid to make it appear convincing – but also realistic, given all the uncertainty – a <a href="https://openresearch-repository.anu.edu.au/handle/1885/53418">veil of vagueness</a> was cast over the national plan. The document is full of weasel-words and caveats, which means it is impossible for anyone to be held to account. </p>
<p>The <a href="https://www.pm.gov.au/media/national-cabinet-statement-10">equivocal “in-principle” condition on National Cabinet’s approval</a> makes it even harder to know exactly what premiers signed up to. </p>
<p>But the severity of the New South Wales outbreak has forced some of our leaders to take off the rose-coloured glasses and adopt a more realistic view. Premiers are now saying they did not sign up to high death tolls. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1429533885537394693"}"></div></p>
<p>According to Doherty modelling, deaths could reach 1,500 within six months of implementing Phase B. Agreeing to such a scenario is politically untenable for states that currently have zero cases. </p>
<h2>3. So, what should happen next?</h2>
<p>With states divided over the national plan, and the modelling potentially out of date, it’s time for National Cabinet to come back with a new approach. We need a revised national plan – one that all states can sign up to, one that is not full of caveats and conditions. </p>
<p>This should include a realistic plan for scaling up testing-tracing-isolation-quarantine capacity so that it can manage in a feasible way when each infected person could have at least ten new contacts per day. </p>
<p>And it should include a plan to protect primary schools and childcare centres while a vaccine remains unavailable for younger children. </p>
<p>Grattan Institute has also done <a href="https://grattan.edu.au/report/race-to-80/">its own modelling</a>. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1420851138941751298"}"></div></p>
<p>But our model was about Phase D – what Australia needs to do to avoid obtrusive restrictions such as lockdowns altogether – which was not modelled by the Doherty Institute. </p>
<p>We argued that it is only safe to open the borders, to lift restrictions, and to manage without lockdowns and use only unobtrusive measures such as masks on public transport, if we vaccinate at least 80% of the total population and continue the vaccination rollout to 90% throughout 2022. </p>
<p>Recent <a href="https://osf.io/ytkdg/">modelling from other academics</a> has come to similar conclusions, with some even suggesting a slightly higher threshold for safe re-opening.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1430028852508700674"}"></div></p>
<p>Governments cannot keep making unrealistic promises about easing restrictions at 70% and 80% adult vaccination, a plan that relied on optimistic scenarios in the first place, and one that now bears little relation to the real world. It is irresponsible to build public momentum and hope around targets that are unlikely going to be enough. </p>
<p>Australia needs the National Cabinet to come clean and accept that the changing circumstances require a change in the plan.</p><img src="https://counter.theconversation.com/content/166659/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Grattan Institute began with contributions to its endowment from each of the Federal and Victorian Governments, BHP Billiton, and NAB. In order to safeguard its independence, Grattan Institute’s board controls this endowment. Grattan Institute also receives funding from corporates, foundations, and individuals to support its general activities as disclosed on its website.</span></em></p><p class="fine-print"><em><span>Anika Stobart does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Governments cannot keep making unrealistic promises about easing restrictions at 70% and 80% adult vaccination, a plan that relied on optimistic scenarios in the first place.Stephen Duckett, Director, Health and Aged Care Program, Grattan InstituteAnika Stobart, Associate, Grattan InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1664252021-08-23T05:46:53Z2021-08-23T05:46:53ZHigh priority: why we must vaccinate children aged 12 and over now<figure><img src="https://images.theconversation.com/files/417324/original/file-20210823-23-1j404lh.jpg?ixlib=rb-1.1.0&rect=0%2C20%2C6709%2C4446&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>People <a href="https://www.health.gov.au/initiatives-and-programs/covid-19-vaccines/getting-vaccinated-for-covid-19/covid-19-vaccination-program-for-16-to-39-year-olds">aged 16 and above</a> will soon be able to get a COVID vaccine in Australia, but this begs the question: what about children in younger age groups?</p>
<p>Currently, only 12-15 year olds with underlying medical conditions, Aboriginal and Torres Strait Islander children, and those living in remote communities are <a href="https://www.health.gov.au/ministers/the-hon-greg-hunt-mp/media/pfizer-covid-19-vaccine-approved-for-at-risk-children-aged-12-15-years">eligible</a>. </p>
<p><a href="https://www.doherty.edu.au/uploads/content_doc/DohertyModelling_NationalPlan_and_Addendum_20210810.pdf">Modelling</a> by the Doherty Institute has suggested vaccinating 12-15 year olds would not make a material difference to the COVID epidemic.</p>
<p>However, as a researcher with expertise on modelling infectious diseases, it’s my view children aged 12 and over must be vaccinated with high priority.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-may-need-to-vaccinate-children-as-young-as-5-to-reach-herd-immunity-with-delta-our-modelling-shows-164942">We may need to vaccinate children as young as 5 to reach herd immunity with Delta, our modelling shows</a>
</strong>
</em>
</p>
<hr>
<h2>Children and transmission</h2>
<p>A key concept you might have heard about is the reproduction number — the number of new cases per infectious case. For the Delta strain, this number could be <a href="https://www.theguardian.com/commentisfree/2021/aug/20/it-might-not-feel-like-it-as-cases-rise-but-nsw-is-controlling-delta">as high as nine</a>. In other words, if there were no lockdowns or other controls in place, each Delta infection could theoretically lead to as many as nine new infections.</p>
<p>The “effective reproduction number” is how many new cases you get per infectious case <em>after</em> public health measures such as lockdowns have been applied. </p>
<p>The Doherty modelling used a baseline effective reproduction number of 3.6 but acknowledges the effective reproduction number will be different from state to state. It can also change over time.</p>
<p>The effective reproduction numbers in NSW and Victoria are currently under two — but this figure could rise when lockdowns lift.</p>
<p><a href="https://theconversation.com/we-may-need-to-vaccinate-children-as-young-as-5-to-reach-herd-immunity-with-delta-our-modelling-shows-164942">Modelling</a> by colleagues and I shows that once the value of the effective reproduction number creeps up above four, all else being equal, children including those younger than 16 start to feature highly in transmission.</p>
<p>In other words, we need to vaccinate children aged 12 and above now, in preparation for a scenario when the effective reproduction number is much higher than it has been under lockdowns.</p>
<h2>A reality check</h2>
<p>In a scenario where children aged 12 and above are returning to school and moving around the community unvaccinated, could masks and social distancing be enough? </p>
<p>Well, perhaps in an ideal world. But many simply assume children will be able to socially distance and wear masks just like adults do. Parents may wish to reflect on that. </p>
<p>We also need to compare old assumptions about COVID and children with what we are now seeing in reality. </p>
<p>The original strain of COVID-19 appeared to spare children; they were less likely than older people to be infected in the first place. The Delta strain seems to have <a href="https://theconversation.com/should-we-vaccinate-children-against-covid-19-we-asked-5-experts-165316">changed</a> all that.</p>
<p>According to <a href="https://www.nsw.gov.au/covid-19/find-the-facts-about-covid-19">NSW Health</a>’s factsheet on coronavirus disease in NSW, only one person under 20 has died due to COVID. However, people in this age group are showing up significantly in overall case numbers. </p>
<p>Since NSW began its current lockdown, <a href="https://data.nsw.gov.au/search/dataset/ds-nsw-ckan-3dc5dc39-40b4-4ee9-8ec6-2d862a916dcf/details?q=">about one third of new COVID</a> cases in NSW (around 3,000) have been in under 20 year olds.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/417319/original/file-20210823-21-1xe4fo0.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/417319/original/file-20210823-21-1xe4fo0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/417319/original/file-20210823-21-1xe4fo0.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=237&fit=crop&dpr=1 600w, https://images.theconversation.com/files/417319/original/file-20210823-21-1xe4fo0.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=237&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/417319/original/file-20210823-21-1xe4fo0.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=237&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/417319/original/file-20210823-21-1xe4fo0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=298&fit=crop&dpr=1 754w, https://images.theconversation.com/files/417319/original/file-20210823-21-1xe4fo0.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=298&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/417319/original/file-20210823-21-1xe4fo0.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=298&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">According to NSW Health, only one person under 20 has died due to COVID but people in this age group are showing up significantly in overall case numbers.</span>
<span class="attribution"><a class="source" href="https://www.nsw.gov.au/covid-19/find-the-facts-about-covid-19">NSW Health</a></span>
</figcaption>
</figure>
<p>Victoria’s chief health officer has also noted childcare centres and schools feature heavily <a href="https://www.dhhs.vic.gov.au/covid-19-chief-health-officer-update#update-outbreaks">among the hotspots in that state</a>.</p>
<p>If Delta does end up infecting children more than the original strain did, children may become the super-spreaders of the Delta variant — just as they are key transmitters of influenza, pertussis, measles, chicken pox and just about every respiratory virus.</p>
<p>Now, some expert groups — <a href="https://www.theaustralian.com.au/nation/politics/how-to-stop-spread-of-covid19-delta-variant-jab-all-teenagers/news-story/7287ea97986dcaff39125c4cb7b3ca55">including modellers</a> — are starting to call for younger children to be vaccinated with high priority. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1428814688154832897"}"></div></p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/should-we-vaccinate-children-against-covid-19-we-asked-5-experts-165316">Should we vaccinate children against COVID-19? We asked 5 experts</a>
</strong>
</em>
</p>
<hr>
<h2>Which vaccine? While Pfizer is scarce, we should direct it to younger people</h2>
<p>While Pfizer is scarce, we should be providing Pfizer to the younger population (who are <a href="https://www.doherty.edu.au/uploads/content_doc/DohertyModelling_NationalPlan_and_Addendum_20210810.pdf">more likely</a> to <a href="https://theconversation.com/we-may-need-to-vaccinate-children-as-young-as-5-to-reach-herd-immunity-with-delta-our-modelling-shows-164942">transmit COVID-19</a>), while giving AstraZeneca to older people. </p>
<p>While both vaccines are over 90% effective at reducing death and severe outcomes from COVID (including Delta), <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa2108891">Pfizer is better than AstraZeneca at reducing transmission</a> of the virus.</p>
<p>In Australia, children 12-17 are approved to receive Pfizer but not AstraZeneca. </p>
<h2>What are the consequences of not vaccinating younger children?</h2>
<p>The risks of not vaccinating children in the 12+ age group include:</p>
<ul>
<li><p>more children becoming sick with COVID</p></li>
<li><p>denying children potential freedoms that may come with vaccination, such as returning to school, travel or avoiding strict lockdowns</p></li>
<li><p>not vaccinating children means living with the knowledge we haven’t done everything possible to ensure they don’t transmit COVID to more vulnerable people.</p></li>
</ul>
<p>It’s unlikely Australia will achieve herd immunity to COVID this year. </p>
<p>But even without herd immunity, every little bit helps — and the growing number of cases in younger children suggests we need to vaccinate this group sooner, rather than later.</p><img src="https://counter.theconversation.com/content/166425/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emma McBryde receives funding from the NHMRC and the MRFF. She previously worked for the Doherty Institute. </span></em></p>Not vaccinating children means living with the knowledge we haven’t done everything possible to ensure they don’t transmit COVID to more vulnerable people.Emma McBryde, Professor of Infectious Disease and Epidemiology, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1654592021-08-09T19:59:00Z2021-08-09T19:59:00ZWhen will Sydney’s lockdown end? Well, it depends who you ask<figure><img src="https://images.theconversation.com/files/414967/original/file-20210806-21-1c38j60.jpg?ixlib=rb-1.1.0&rect=2%2C1%2C995%2C663&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sydney-nsw-australia-15th-2021-isolated-2008345958">from www.shutterstock.com</a></span></figcaption></figure><p>During the pandemic, infectious disease modelling has come to prominence as never before. A <a href="https://amp.smh.com.au/national/nsw/scientists-split-over-whether-sydney-s-lockdown-is-tight-enough-to-tame-outbreak-20210728-p58dpk.html">plethora of models</a> have been used to guide policy. </p>
<p>The models use computer programs to predict, for example, how COVID outbreaks develop and which public health measures are most likely to contain them, under different future scenarios.</p>
<p>Among the big questions modellers are trying to answer currently is what should Sydney’s strategy be for addressing its current Delta outbreak, to allow release from lockdown while minimising COVID-related deaths.</p>
<p>Different groups of researchers give different predictions. And it’s easy to be bewildered, especially if you’re in lockdown and looking for answers.</p>
<h2>Why do answers vary?</h2>
<p>At their best, infectious disease models should provide a way of integrating all the available information relevant to the problem at hand. This includes the characteristics of the virus circulating, the scope of the epidemic, the history of the outbreak to date, and evidence from clinical trials and other research. </p>
<p>We can then use this to challenge our own ideas about what the best policy response should be and develop a high-level strategy for the future.</p>
<p>Many of the mathematical models that have informed COVID policy across the world have been “mechanistic”. They explicitly represent the population in which the virus is transmitting and so simulate the process of susceptible people becoming infected with the virus through exposure to others. </p>
<p>Although many other mathematical techniques have been used during the pandemic, this approach has the advantage of being able project the outcomes of a wide range of policy responses.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/scientific-modelling-is-steering-our-response-to-coronavirus-but-what-is-scientific-modelling-135938">Scientific modelling is steering our response to coronavirus. But what is scientific modelling?</a>
</strong>
</em>
</p>
<hr>
<p>This approach also has several limitations. One of the most important is that tiny changes in what you feed into the model can have a huge effect on the output.</p>
<p>Another important consideration is that future projections inevitably represent the expected outcomes under a particular set of policy choices, which are impossible for modellers to predict.</p>
<p>In short, infectious disease epidemics are difficult to predict because their dynamics are volatile and dependent on the policies we choose to implement.</p>
<h2>Let’s look at the Sydney predictions</h2>
<p>Several groups have modelled Sydney’s lockdown recently and have shared their results with the public. These include groups at the <a href="https://burnet.edu.au/news/1465_likely_stage_4_tighter_restriction_levels_will_be_needed_to_control_the_current_delta_variant_outbreak_in_nsw_new_modelling_shows">Burnet Institute</a> and at the <a href="https://www.sydney.edu.au/news-opinion/news/2021/07/30/social-distancing-up-but-still-inadequate-to-control-outbreak.html">universities of Sydney</a> and <a href="https://pursuit.unimelb.edu.au/articles/how-long-till-sydney-gets-out-of-lockdown">Melbourne</a>.</p>
<p><strong>The Burnet model</strong></p>
<p>The Burnet Institute simulates individuals and their characteristics and behaviours (an agent-based model). It can mimic the social networks through which individuals interact in specific settings, fundamental to how the epidemic spreads.</p>
<p>This approach is particularly well-suited to considering interventions that affect groups of people interacting. These include closing specific venues or activities, such as restaurants, gyms, schools or sporting events.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/415138/original/file-20210809-21-wtzhqi.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/415138/original/file-20210809-21-wtzhqi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/415138/original/file-20210809-21-wtzhqi.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/415138/original/file-20210809-21-wtzhqi.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/415138/original/file-20210809-21-wtzhqi.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/415138/original/file-20210809-21-wtzhqi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/415138/original/file-20210809-21-wtzhqi.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/415138/original/file-20210809-21-wtzhqi.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Burnet Institute’s modelling shows that without the initial stay-at-home orders, the results would have been catastrophic (red line).</span>
<span class="attribution"><a class="source" href="https://theconversation.com/a-tougher-4-week-lockdown-could-save-sydney-months-of-stay-at-home-orders-our-modelling-shows-164483">Burnet Institute</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-tougher-4-week-lockdown-could-save-sydney-months-of-stay-at-home-orders-our-modelling-shows-164483">A tougher 4-week lockdown could save Sydney months of stay-at-home orders, our modelling shows</a>
</strong>
</em>
</p>
<hr>
<p>This model, <a href="https://burnet.edu.au/news/1465_likely_stage_4_tighter_restriction_levels_will_be_needed_to_control_the_current_delta_variant_outbreak_in_nsw_new_modelling_shows">released July 12</a>, predicted a more stringent lockdown (blue line in the chart above; something like Melbourne’s stage 4 lockdown in 2020) should be enough to drive case numbers in Sydney back down towards low levels (less than five new local cases per day) over several weeks. This would lead to elimination of the virus, allowing lockdown to lift.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Burnet Institute, July 12</span></span>
</figcaption>
</figure>
<p><strong>University of Sydney model</strong></p>
<p>The University of Sydney model is also an agent-based model, similar in several ways to the Burnet model. It builds on previous work on modelling influenza in which the researchers constructed a detailed representation of the Australian population using census data.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1420999846241083398"}"></div></p>
<p>Along with their COVID status, the age, gender, residence and workplace of individuals is simulated, along with their commuting patterns. Various interventions are simulated, including isolating contacts of cases in quarantine, and social distancing.</p>
<p>The Sydney model found that unless interactions between people are reduced substantially for several weeks, the epidemic is unlikely to decline rapidly.</p>
<p><strong>University of Melbourne model</strong></p>
<p>The University of Melbourne model represents people or groups of people as agents who move in two-dimensional space, potentially becoming infected as susceptible agents interact with infected ones. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1417403357933674496"}"></div></p>
<p>Because discrete individuals are represented, models like this can be used to define when the last case has recovered and elimination has been achieved.</p>
<p>This model generally had more optimistic findings for Sydney than the other two, with most model runs showing the epidemic dying away within two months if current restrictions or tighter are sustained. Unfortunately, case numbers already seem to be escalating beyond these predictions.</p>
<figure class="align-center ">
<img alt="The University of Melbourne's modelling of Sydney's COVID outbreak" src="https://images.theconversation.com/files/415160/original/file-20210809-17-1a12kvd.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/415160/original/file-20210809-17-1a12kvd.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=335&fit=crop&dpr=1 600w, https://images.theconversation.com/files/415160/original/file-20210809-17-1a12kvd.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=335&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/415160/original/file-20210809-17-1a12kvd.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=335&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/415160/original/file-20210809-17-1a12kvd.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=421&fit=crop&dpr=1 754w, https://images.theconversation.com/files/415160/original/file-20210809-17-1a12kvd.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=421&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/415160/original/file-20210809-17-1a12kvd.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=421&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The University of Melbourne’s modelling suggested Sydney’s COVID outbreak could take until early September to be brought under control.</span>
<span class="attribution"><a class="source" href="https://www.abc.net.au/news/2021-07-20/nsw-lockdown-needs-to-run-to-september-for-delta-cases-to-drop/100307698">Chart: ABC news. Source: University of Melbourne</a></span>
</figcaption>
</figure>
<h2>The similarities</h2>
<p>Despite some differences in findings, we can take the following messages from these models:</p>
<ul>
<li><p>if there had been no lockdown or if lockdowns were released now, a devastating epidemic would result</p></li>
<li><p>the public health response (including lockdown) is having a major effect in driving down transmission</p></li>
<li><p>with the current response and level of restrictions, at best it will take months to bring the epidemic fully under control</p></li>
<li><p>if restrictions are tightened considerably for at least one to two months, case numbers may decline to the point that elimination could be targeted.</p></li>
</ul>
<h2>Take-home message</h2>
<p>The epidemic in Sydney is at a crossroads, with the only two feasible choices being to go hard towards elimination (as supported by all modelling groups) or to maintain manageable case numbers until vaccination begins to take effect. Current policy choices in NSW appear to prefer the latter. </p>
<p>The next task for modellers should be to simulate this chosen pathway and the length of lockdown it would imply.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-cant-rely-solely-on-arbitrary-vaccination-levels-to-end-lockdowns-here-are-7-ways-to-fix-sydneys-outbreak-165658">We can't rely solely on arbitrary vaccination levels to end lockdowns. Here are 7 ways to fix Sydney's outbreak</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/165459/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The Epidemiological Modelling Unit at the School of Public Health and Preventive Medicine (led by James Trauer) has received funding for COVID-19 research from the NHMRC, the MRFF, the World Health Organization and the Victorian Government Department of Health and Human Services (now the Victorian Department of Health), including to produce epidemic projections during Victoria's second wave in 2020.</span></em></p>Different groups of researchers give different predictions. And it’s easy to be bewildered, especially if you’re in lockdown and looking for answers. Here’s what to make of it all.James Trauer, Associate Professor, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1649422021-08-05T02:58:23Z2021-08-05T02:58:23ZWe may need to vaccinate children as young as 5 to reach herd immunity with Delta, our modelling shows<figure><img src="https://images.theconversation.com/files/414473/original/file-20210804-12-feze9m.jpg?ixlib=rb-1.1.0&rect=0%2C1%2C1000%2C664&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/group-elementary-pupils-classroom-138148427">from www.shutterstock.com</a></span></figcaption></figure><p>Recently released <a href="https://www.doherty.edu.au/news-events/news/doherty-institute-modelling-report-for-national-cabinet">modelling</a> from the Doherty Institute, which the federal government used to back its roadmap out of the pandemic, misses one critical point — the importance of vaccinating children.</p>
<p>The Doherty modelling instead focuses on vaccinating 70-80% of the adult population as thresholds for easing various restrictions, such as lockdowns. It says vaccinating younger adults, in particular, is important to reach these thresholds.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1422469191584657418"}"></div></p>
<p>However, <a href="https://www.medrxiv.org/content/10.1101/2021.07.16.21260642v1">our modelling</a> shows vaccinating children is vital if we are to reach herd immunity, which would allow us to ease restrictions and safely open up. </p>
<p>This would mean potentially vaccinating children as young as 5 years old. </p>
<p>However, we are still waiting to see if this is safe and effective, with trials under way in the United States. So we need a plan that assumes we may never achieve herd immunity.</p>
<p>Here’s what our modelling shows and how it differs from the modelling used to advise the federal government.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-need-to-start-vaccinating-people-in-their-20s-and-30s-according-to-the-doherty-modelling-an-epidemiologist-explains-why-165540">We need to start vaccinating people in their 20s and 30s, according to the Doherty modelling. An epidemiologist explains why</a>
</strong>
</em>
</p>
<hr>
<h2>Here’s what we did</h2>
<p><a href="https://www.medrxiv.org/content/10.1101/2021.07.16.21260642v1">Our modelling</a>, which we’ve uploaded as a pre-print and has yet to be peer-reviewed, considers different vaccine strategies for Australia to achieve herd immunity. That’s when we can expect no sustained transmission of the virus in the community.</p>
<p>We take into account the Delta variant, which is twice as infectious as the original Wuhan strain of the virus, and has a reproduction number estimated between <a href="https://fm.cnbc.com/applications/cnbc.com/resources/editorialfiles/2021/07/30/CDC_slides.pdf">5 and 10</a>. In other words, this is when one person infected with Delta is estimated to infect 5-10 others.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/scientific-modelling-is-steering-our-response-to-coronavirus-but-what-is-scientific-modelling-135938">Scientific modelling is steering our response to coronavirus. But what is scientific modelling?</a>
</strong>
</em>
</p>
<hr>
<p>We also consider different contact patterns across various age groups. This is because some age groups are more mobile and have many contacts. If infected, these people are more likely to infect many others, particularly of similar age, which can lead to reservoirs of transmission. </p>
<p>We combine this information with possible vaccine effects. These include the possibility of having the vaccine then becoming infected, having symptoms, and if infected, how serious the illness is and how infectious people are. </p>
<p>This allows us to model what’s likely, given we’re focused on the Delta variant for now, and allows us to assess the impact of strategies across different age groups, types of vaccines and percentage vaccinated.</p>
<p><a href="https://covid-19-aithm.shinyapps.io/vaccine_coverage_analysis/">Our interactive tool</a> also allows rapid response to changing information, such as new variants, or new evidence about vaccine impact.</p>
<h2>Delta is more infectious</h2>
<p>The Wuhan strain had a <a href="https://ourworldindata.org/explorers/coronavirus-data-explorer?zoomToSelection=true&time=2020-03-01..latest&pickerSort=asc&pickerMetric=location&Metric=Reproduction+rate&Interval=7-day+rolling+average&Relative+to+Population=true&Align+outbreaks=false&country=USA%7EGBR%7ECAN%7EDEU%7EITA%7EIND">basic reproduction number of 2.5</a>. This means, at the start of the pandemic, one person infected with it was expected to infect 2.5 others.</p>
<p>If the Delta variant is twice as infectious, this means its basic reproduction number may be over 5 (at the lower range of international estimates). So this changes the number (and type) of people we need to vaccinate to reach herd immunity considerably.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1400803913993900035"}"></div></p>
<p>The simplest form of the herd immunity equation would suggest we needed to fully immunise 60% of the population to achieve herd immunity for the Wuhan strain but as much as 80% for the Delta variant.</p>
<p>If we take into account how different age groups mingle or are in contact with others, the situation is worse. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-it-more-infectious-is-it-spreading-in-schools-this-is-what-we-know-about-the-delta-variant-and-kids-163724">Is it more infectious? Is it spreading in schools? This is what we know about the Delta variant and kids</a>
</strong>
</em>
</p>
<hr>
<p>For the Wuhan strain, children were not as infectious or susceptible to infection and we predict that if we vaccinate 65% of the adults, transmission would not continue among children.</p>
<p>However, with the Delta variant, we predict children will continue to infect other children, even when most adults are vaccinated.</p>
<p>We also know both the AstraZeneca and Pfizer vaccines are <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa2108891">less able to protect</a> against the Delta variant, with a reduced efficacy after one dose and slightly reduced efficacy after two doses.</p>
<p>All this makes achieving herd immunity a great challenge. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/when-will-we-reach-herd-immunity-here-are-3-reasons-thats-a-hard-question-to-answer-164560">When will we reach herd immunity? Here are 3 reasons that's a hard question to answer</a>
</strong>
</em>
</p>
<hr>
<p>We estimate if the reproduction number is 5, then vaccinating 85% of the population, including children down to age 5, will be necessary to achieve herd immunity. </p>
<p>If the reproduction number is as low as 3, then vaccinating children will not be necessary to achieve herd immunity and we will only need to vaccinate 60% of the population.</p>
<p>The Doherty modelling uses an effective reproduction number of 3.6. This explains why its modelling does not see vaccinating children as critical to reaching herd immunity. This is the major difference between our model and theirs.</p>
<h2>What happens next?</h2>
<p>Of course, new variants may arise pushing Delta aside, and the world post-COVID is unpredictable. </p>
<p>The lesson from Delta is if we don’t vaccinate children, we may need to continue some form of public health action to prevent large-scale circulation of the virus. </p>
<p>This would not require stringent lockdown, but may require ongoing mask use and physical distancing, including in children. The alternative is to reduce the focus on case numbers, expect transmission and focus on protecting the most vulnerable.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/should-we-vaccinate-children-against-covid-19-we-asked-5-experts-165316">Should we vaccinate children against COVID-19? We asked 5 experts</a>
</strong>
</em>
</p>
<hr>
<h2>Do we need to reach herd immunity?</h2>
<p>Herd immunity is not the only possible target. Even if we don’t reach full herd immunity, we may achieve “herd protection”. This provides some reduced risk to people who can’t or won’t be vaccinated, and it will make outbreaks smaller and easier to control.</p>
<p>And without full herd immunity, individuals still benefit from vaccination as they are dramatically less likely to die from COVID.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-well-do-covid-vaccines-work-in-the-real-world-162926">How well do COVID vaccines work in the real world?</a>
</strong>
</em>
</p>
<hr>
<h2>Do we need to change our vaccination strategy?</h2>
<p>We predict Australia’s strategy of vaccinating the elderly and vulnerable first is the best strategy for reducing deaths under most circumstances, particularly when there is insufficient vaccine available. </p>
<p>But once the most vulnerable groups have been covered, we should turn our attention to the highest transmitters to achieve herd protection. In Australia, this group is the late teens and young adults. </p>
<p>Whether we next focus on vaccinating children is controversial and many people have voiced their concerns about going down this path. This is because COVID is generally a very mild illness for most children — although <a href="https://www.thelancet.com/journals/lanchi/article/PIIS2352-4642(21)00124-3/fulltext">long COVID</a> and <a href="https://jamanetwork.com/journals/jama/article-abstract/2777026">life-threatening complications</a> can arise.</p>
<p>So we need to balance the risks with benefits. But included in the benefits should be the potential benefit of herd protection and the freedoms that may bring.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/national-cabinets-plan-out-of-covid-aims-too-low-on-vaccinations-and-leaves-crucial-questions-unanswered-165447">National Cabinet's plan out of COVID aims too low on vaccinations and leaves crucial questions unanswered</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/164942/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emma McBryde receives funding from NHMRC. She is affiliated with the Australian Tuberculosis Forum and the Austrasian Society of Infectious Diseases. </span></em></p>But herd immunity is not our only option. If we don’t vaccinate children, we may have to settle for lesser protection of the population.Emma McBryde, Professor of Infectious Disease and Epidemiology, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1650732021-07-29T20:00:22Z2021-07-29T20:00:22ZAustralia shouldn’t ‘open up’ before we vaccinate at least 80% of the population. Here’s why<figure><img src="https://images.theconversation.com/files/413261/original/file-20210727-13-rejbhp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/casual-blond-young-woman-talking-on-1917201809">Shutterstock</a></span></figcaption></figure><p>Earlier this month National Cabinet released a four-phase <a href="https://www.pm.gov.au/media/national-cabinet-statement-6">COVID response plan</a>. It wasn’t so much a plan – it had no dates and no thresholds – but more a back-of-the-napkin thought bubble. It was <a href="https://theconversation.com/australia-has-a-new-four-phase-plan-for-a-return-to-normality-heres-what-we-know-so-far-163804">sensible, but vague</a>.</p>
<p>National Cabinet now faces the hard task of converting vagueness into a real plan. To do this it must answer the question: what proportion of the Australian population needs to be vaccinated before we can open our international borders?</p>
<p>This means allowing stranded Australians to return, letting footloose people travel overseas, and welcoming international tourists and students again. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/australia-has-a-new-four-phase-plan-for-a-return-to-normality-heres-what-we-know-so-far-163804">Australia has a new four-phase plan for a return to normality. Here's what we know so far</a>
</strong>
</em>
</p>
<hr>
<p>Well qualified experts <a href="https://www.afr.com/policy/health-and-education/the-politicisation-of-pandemic-punditry-20210721-p58brg">differ on the requisite threshold for vaccination</a> partly because there are so many unknowns, such as how quickly the Delta variant of COVID would spread through Australia if we open up, and how effective the different vaccines will prove to be in preventing transmission.</p>
<p>But new <a href="http://grattan.edu.au">Grattan Institute modelling</a> shows it would be dangerous for Australia to open up before at least 80% of the population is vaccinated. </p>
<p>Here’s what we found, and how we came to the 80% figure. Let’s start with the good news.</p>
<h2>Vaccines offer substantial protection</h2>
<p>Both vaccines on offer in Australia – Pfizer and AstraZeneca – are effective at preventing infections from the Delta strain. Two doses of Pfizer <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa2108891">offers</a> about 88% protection against infection, while two doses of AstraZeneca offers about 67% protection. </p>
<p>Vaccinated people can still catch COVID, but those that do pass it on to about half as many others compared to the unvaccinated. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/yes-you-can-still-get-covid-after-being-vaccinated-but-youre-unlikely-to-get-as-sick-163870">Yes, you can still get COVID after being vaccinated, but you're unlikely to get as sick</a>
</strong>
</em>
</p>
<hr>
<p>Evidence from the United Kingdom, Canada, and the European Union – areas with higher vaccination levels than Australia – also suggests both vaccines offer substantial protection against hospitalisation and death from COVID. A vaccinated person is about <a href="https://media.tghn.org/articles/Effectiveness_of_COVID-19_vaccines_against_hospital_admission_with_the_Delta_B._G6gnnqJ.pdf">95% less likely</a> than an unvaccinated person to end up in hospital with COVID.</p>
<p>Now for the bad news.</p>
<h2>The delta strain is far more infectious</h2>
<p>Researchers estimate the Delta variant is <a href="https://jglobalbiosecurity.com/articles/10.31646/gbio.121/">50% to 100% more infectious than the Alpha variant</a>, which itself was more transmissible than the variant that was dominant throughout 2020. </p>
<p>The effective reproduction number, or Reff, tells us how many people one infected person will spread the virus to, taking into account behaviour and public health measures in place designed to reduce transmission, such as masks and physical distancing.</p>
<figure class="align-center ">
<img alt="A masked supermarket check out operator scans products." src="https://images.theconversation.com/files/413509/original/file-20210728-27-147471c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/413509/original/file-20210728-27-147471c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/413509/original/file-20210728-27-147471c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/413509/original/file-20210728-27-147471c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/413509/original/file-20210728-27-147471c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/413509/original/file-20210728-27-147471c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/413509/original/file-20210728-27-147471c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Reff changes according to the public health measures in place, such as mask mandates.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cashier-supermarket-staff-medical-protective-mask-1680373474">Shutterstock</a></span>
</figcaption>
</figure>
<p>If the Reff of the Delta variant in Australia is around 6 without vaccination, having 50% vaccination coverage will reduce the Reff to 3.</p>
<p>But the national goal must be to bring the Reff down to below 1, which would mean each person who was infected would infect less than one other person – and the virus would eventually peter out.</p>
<p>The higher the vaccination rate, the lower the effective reproduction number. Each person vaccinated offers a chance of breaking a chain of transmission that might lead to an outbreak. </p>
<p>Not only are vaccinated people less likely to become infected, they are also less likely to pass the virus onto others if they are.</p>
<p><strong>The higher the vaccination rate, the lower the effective reproduction number</strong></p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/413513/original/file-20210728-13-1wsg5r1.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/413513/original/file-20210728-13-1wsg5r1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/413513/original/file-20210728-13-1wsg5r1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=595&fit=crop&dpr=1 600w, https://images.theconversation.com/files/413513/original/file-20210728-13-1wsg5r1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=595&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/413513/original/file-20210728-13-1wsg5r1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=595&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/413513/original/file-20210728-13-1wsg5r1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=748&fit=crop&dpr=1 754w, https://images.theconversation.com/files/413513/original/file-20210728-13-1wsg5r1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=748&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/413513/original/file-20210728-13-1wsg5r1.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=748&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Effective reproduction number (Reff) by population vaccination rate.</span>
<span class="attribution"><span class="source">Grattan Institute</span></span>
</figcaption>
</figure>
<h2>So why do we need 80% of people vaccinated?</h2>
<p><a href="https://github.com/grattan/covidReff">Grattan Institute’s model</a> simulates the spread of COVID within a partially vaccinated population, and helps us peek into the future.</p>
<p>It uses age-based hospitalisation and intensive care unit (ICU) admission rates from more than a year of COVID data from Australian ICU units. It also assumes children under 16 are about one-fifth less likely to get COVID, and children over the age of two are able to be vaccinated.</p>
<p>In most of our simulations, older people have higher rates of vaccination, and no age group has more than 95% vaccine coverage.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/when-will-we-reach-herd-immunity-here-are-3-reasons-thats-a-hard-question-to-answer-164560">When will we reach herd immunity? Here are 3 reasons that's a hard question to answer</a>
</strong>
</em>
</p>
<hr>
<p>We ran thousands of simulations of different vaccination rates, and different estimates of the Reff. The outcomes for 12 distinct scenarios are shown in the table below. </p>
<p>You can see why we recommend Australia not open up until at least 80% of the population is vaccinated – it is the only scenario where the virus is managed, with hospitalisations and deaths kept down to reasonable levels, even if the Reff is high.</p>
<hr>
<iframe src="https://flo.uri.sh/visualisation/6859968/embed" title="Interactive or visual content" class="flourish-embed-iframe" frameborder="0" scrolling="no" style="width:100%;height:1500px;" sandbox="allow-same-origin allow-forms allow-scripts allow-downloads allow-popups allow-popups-to-escape-sandbox allow-top-navigation-by-user-activation" width="100%" height="400"></iframe>
<div style="width:100%!;margin-top:4px!important;text-align:right!important;"><a class="flourish-credit" href="https://public.flourish.studio/visualisation/6859968/?utm_source=embed&utm_campaign=visualisation/6859968" target="_top"><img alt="Made with Flourish" src="https://public.flourish.studio/resources/made_with_flourish.svg"> </a></div>
<hr>
<h2>Let’s break it down</h2>
<p>Our simulations show that opening up at 50% vaccination rate (scenario 1) is a very bad idea, with many, many thousands of deaths.</p>
<p>Scenarios 2 and 3 are the optimist’s and gambler’s scenarios. If you are lucky and the Reff of Delta in Australia is 4 (with 70% vaccination rate) or 5 (with 75% vaccination rate), deaths and hospitalisations would not rise above moderate levels, and lockdowns could end and the borders could reopen. </p>
<p>But if you gambled on the wrong Reff, our hospitals would be overwhelmed and deaths would be unacceptably high. Opening the borders is a one-shot gamble: if you make the wrong call, the virus will quickly spread and all the good work and hard yards of living through lock-downs over the previous two years will have been wasted.</p>
<p>Public health decision-making is often risk averse, for the best of reasons. The difference in virus spread, hospitalisations and deaths between opening at 75% and at 80% are big, but the wait between the two thresholds may only be a month or two.
This is why we recommend an 80% vaccination rate (scenario 4) as the threshold for opening up. </p>
<p>Even if the Reff of Delta is 6, our hospital system will not be overwhelmed, and deaths will not rise above the number of deaths in a moderate flu season, such as 2010, when there were <a href="https://www1.health.gov.au/internet/main/publishing.nsf/Content/cdi4104-f">2,364 flu deaths</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/80-vaccination-wont-get-us-herd-immunity-but-it-could-mean-safely-opening-international-borders-162863">80% vaccination won't get us herd immunity, but it could mean safely opening international borders</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/165073/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephen Duckett has had his first AstraZeneca vaccination.
Grattan Institute began with contributions to its endowment of $15 million from each of the Federal and Victorian Governments, $4 million from BHP Billiton, and $1 million from NAB. In order to safeguard its independence, Grattan Institute’s board controls this endowment. The funds are invested and contribute to funding Grattan Institute's activities. Grattan Institute also receives funding from corporates, foundations, and individuals to support its general activities, as disclosed on its website. Stephen Duckett has been partially vaccinated with AstraZeneca.</span></em></p><p class="fine-print"><em><span>Will Mackey does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>If we open up the international borders before enough of the population is vaccinated, hospitals could become overwhelmed and deaths would be unacceptably high.Stephen Duckett, Director, Health Program, Grattan InstituteWill Mackey, Senior Associate, Grattan InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1645482021-07-16T04:11:40Z2021-07-16T04:11:40ZVictoria’s 5-day lockdown may not quash Delta. Here’s what our modelling predicts instead<p>Victoria has entered <a href="https://www.abc.net.au/news/2021-07-16/victoria-awakes-to-its-fifth-coronavirus-lockdown/100296390">a five-day lockdown</a> to control its growing outbreak of the more infectious Delta variant.</p>
<p>Until <a href="https://www.abc.net.au/news/2021-07-15/melbourne-snap-lockdown-covid-19-restrictions-pandemic-/100296392">midnight on Tuesday</a> <a href="https://www.coronavirus.vic.gov.au/coronavirus-covidsafe-settings">restrictions mean</a> residents are only allowed to leave home for essential reasons, can only travel five kilometres away from home, and need to wear masks outside the home, among other measures.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1415814260081532931"}"></div></p>
<p>We consider the lockdown essential and we strongly support this rapid action. However <a href="https://www.medrxiv.org/content/10.1101/2021.07.06.21260055v1.full.pdf">our modelling</a> predicts a five-day lockdown may not be enough. </p>
<p>Instead we predict at least 30 days of restrictions will be needed before Victoria reaches three days without community transmission.</p>
<p>That’s if we take into account current and predicted case numbers, the fact we’re dealing with the more infectious Delta variant, and with current levels of vaccination.</p>
<p>The good news is Victoria is more likely to reach these three “donut days” sooner if vaccination rates pick up, even modestly.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-is-delta-such-a-worry-its-more-infectious-probably-causes-more-severe-disease-and-challenges-our-vaccines-163579">Why is Delta such a worry? It's more infectious, probably causes more severe disease, and challenges our vaccines</a>
</strong>
</em>
</p>
<hr>
<h2>How did we come up with these figures?</h2>
<p>We built a mathematical model based on nine COVID-19 outbreaks across four Australian states (including Victoria) since the start of the pandemic. We posted <a href="https://www.medrxiv.org/content/10.1101/2021.07.06.21260055v1">details online as a pre-print</a>. So our model has yet to be independently verified (peer reviewed).</p>
<p>Our model allows us to predict — given current case numbers, the particular variant in circulation and vaccination rates, among other variables — how long public health restrictions such as lockdowns need to last to achieve particular outcomes. Our model also allows us to predict how many cases an outbreak has at its peak.</p>
<p>Models are mathematical tools to predict the future, something of course no-one can do with 100% certainty.</p>
<p>However, our model differs from others because it considers the difference between mystery cases and cases linked to a known case.</p>
<p>It also comprehensively integrates the effects of various public health measures, such as social distancing, wearing masks, contact tracing and vaccination.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/scientific-modelling-is-steering-our-response-to-coronavirus-but-what-is-scientific-modelling-135938">Scientific modelling is steering our response to coronavirus. But what is scientific modelling?</a>
</strong>
</em>
</p>
<hr>
<h2>What did we find about Victoria?</h2>
<p>When we plug data about Victoria’s current outbreak into our model, this is what we find.</p>
<p>Our model predicts the number of daily reported cases of community transmission will continue to climb over the next week or so. Even with the current lockdown we predict a peak of at least 30 cases a day over the next 7-14 days. </p>
<p>We predict the current outbreak will last for at least 30-45 days before Victoria can return to three days of zero community transmission.</p>
<p>Measured easing of restrictions can occur before this time, which Victorian Premier Daniel Andrews <a href="https://www.abc.net.au/news/2021-07-16/victoria-awakes-to-its-fifth-coronavirus-lockdown/100296390">flagged</a> might be possible for <a href="https://www.abc.net.au/news/2021-07-15/regional-communities-glimmer-of-hope-early-end-to-lockdown/100297258">regional Victoria</a>.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1415565682415063043"}"></div></p>
<p>However, given the fact Delta <a href="https://theconversation.com/why-is-delta-such-a-worry-its-more-infectious-probably-causes-more-severe-disease-and-challenges-our-vaccines-163579">is more transmissible</a> than the original Wuhan version of the virus, controlling Victoria’s outbreak will inevitably be more difficult and take longer than dealing with an earlier outbreak of similar size.</p>
<p>New South Wales knows too well <a href="https://www.abc.net.au/news/2021-07-16/nsw-records97-new-covid-19-cases/100298196">how hard it is</a> to get a Delta outbreak under control, something our model predicted.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-tougher-4-week-lockdown-could-save-sydney-months-of-stay-at-home-orders-our-modelling-shows-164483">A tougher 4-week lockdown could save Sydney months of stay-at-home orders, our modelling shows</a>
</strong>
</em>
</p>
<hr>
<p>Back to Victoria, our model supports a hard lockdown that minimises the chance of ongoing transmission. </p>
<p>Strict lockdown (80% reduction in social activities) and mandatory mask use in public spaces and workplaces (90% coverage) — equivalent to what’s expected in Victoria’s current lockdown — have been effective in previous outbreaks in Victoria and other states. </p>
<p>However, we predict the same approaches may only have a 50:50 chance to contain the current Delta outbreak in Victoria.</p>
<p>This means the Delta variant is likely to linger, bouncing at a level of a dozen cases for weeks. This means public health authorities will find it hard to decide how and when to lift restrictions.</p>
<h2>Please give me good news</h2>
<p>In our favour is <a href="https://www.abc.net.au/news/2021-03-02/charting-australias-covid-vaccine-rollout/13197518">at least 25% of Victorians</a> <a href="https://www.theage.com.au/national/covid-19-global-vaccine-tracker-and-data-centre-20210128-p56xht.html">have received</a> at least one dose of a COVID vaccine.</p>
<p>Our model suggests even modest rises in the vaccination coverage in Victoria, by an additional 5% for example, would dramatically increase the chance of controlling the outbreak from 50% to over 80%. If an extra 10% were vaccinated the chance of controlling the outbreak is 94%.</p>
<p>This is because evidence is mounting vaccinated people are <a href="https://theconversation.com/mounting-evidence-suggests-covid-vaccines-do-reduce-transmission-how-does-this-work-160437">less likely to transmit</a> the virus to others. That’s in addition to the vaccines’ well known benefits in reducing your chance of severe disease.</p>
<p>So getting as many Victorians vaccinated as quickly as possible is critical.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/should-i-get-my-second-astrazeneca-dose-yes-it-almost-doubles-your-protection-against-delta-163259">Should I get my second AstraZeneca dose? Yes, it almost doubles your protection against Delta</a>
</strong>
</em>
</p>
<hr>
<h2>What do we make of all this?</h2>
<p>Our study conveys a simple message. The battle against the Delta variant in the latest outbreak in Victoria will likely be tough but going early has given us the best chance. </p>
<p>This lockdown will not be as effective as earlier ones in Victoria and coming out of this will need to be carefully managed. </p>
<p>So keeping to the health advice, and vaccinating more Victorians as soon as possible even over the next few weeks, are key to handling this outbreak.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/lockdowns-dont-get-easier-the-more-we-have-them-melbourne-here-are-6-tips-to-help-you-cope-161991">Lockdowns don't get easier the more we have them. Melbourne, here are 6 tips to help you cope</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/164548/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lei Zhang is also a professor at Xi’an Jiaotong University, China.</span></em></p><p class="fine-print"><em><span>Christopher Fairley owns shares in CSL.</span></em></p><p class="fine-print"><em><span>Guihua Zhuang and Zhuoru Zou do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The good news is Victoria is more likely to reach zero case of community transmission sooner if vaccination rates pick up, even modestly.Lei Zhang, Associate Professor of Public Health, Monash UniversityChristopher Fairley, Professor of Public Health, Monash UniversityGuihua Zhuang, Professor, Xi'an Jiaotong UniversityZhuoru Zou, Doctor, Xi'an Jiaotong UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1644832021-07-14T05:52:52Z2021-07-14T05:52:52ZA tougher 4-week lockdown could save Sydney months of stay-at-home orders, our modelling shows<p>Residents in Sydney, the NSW Central Coast, Blue Mountains and Wollongong <a href="https://www.theguardian.com/australia-news/2021/jul/14/sydney-covid-19-lockdown-restrictions-nsw-update-coronavirus-face-mask-rules-explained-greater-syd-masks-indoors-singing-dancing-weddings-public-transport-new-south-wales">today received confirmation</a> their lockdown would be extended to at least 30 July. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1415120488502685696"}"></div></p>
<p>But our modelling suggests it may take until the end of the year to get case numbers close to zero, unless more stringent measures are introduced. </p>
<p>NSW health authorities <a href="https://www.nsw.gov.au/covid-19/rules/greater-sydney">increased restrictions</a> on Friday. These <a href="https://www.health.nsw.gov.au/news/Pages/20210709_03.aspx">limit</a> outdoor gatherings to two people, exercise to within 10km from your home, and shopping to one person from a household each day, with no browsing. </p>
<p>These restrictions are similar to Victoria’s Stage 3 and came on top of existing rules, which began on June 23, to only leave your home for four reasons: work/education, care/compassion, shopping for essential supplies, and exercise.</p>
<p>But additional measures – at least as strong as in Melbourne’s Stage 4 – are needed to get the greater Sydney outbreak under control. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411147/original/file-20210714-23-sm3g2c.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p>For Melbourne’s second wave, this included closing non-essential retail, restricting movements to 5km from home and within the hours of 8pm to 5am, and mask-wearing outdoors.</p>
<p>COVID case numbers will fall if Victorian Stage 4 measures are applied in greater Sydney, for at least a month.</p>
<h2>Our predictions</h2>
<p>Our modelling shows that without the initial stay-at-home orders, the results would have been catastrophic (red line).</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/411145/original/file-20210714-17-1xqt16p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411145/original/file-20210714-17-1xqt16p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=379&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411145/original/file-20210714-17-1xqt16p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=379&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411145/original/file-20210714-17-1xqt16p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=379&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411145/original/file-20210714-17-1xqt16p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=477&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411145/original/file-20210714-17-1xqt16p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=477&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411145/original/file-20210714-17-1xqt16p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=477&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p>NSW’s updated level of restrictions (orange line, similar to Victoria’s Stage 3 + masks) would prevent daily case numbers from increasing further. But it’s not enough to eliminate community transmission before the end of the year.</p>
<p>But if Stage 4 restrictions were applied now (blue line), the epidemic curve would decline sharply. </p>
<p>It’s difficult to estimate the time to return case numbers from current levels to a seven-day average of less than five per day, but it’s likely to take at least a month.</p>
<p>So how did we reach these conclusions? We use two complementary modelling approaches to generate information about the measures needed to get case numbers under control. </p>
<h2>Simulating people’s decisions</h2>
<p>The first model, <a href="https://github.com/institutefordiseasemodeling/covasim">COVASIM</a>, simulates individual people who reflect the diversity of the population. Individuals are allocated different numbers of daily contacts and can participate in various activities (for example going to school, work, bars/cafes, shopping, playing sport), which affect their risk of transmission.</p>
<p>People respond differently to COVID-19: whether they get tested, how long they wait before being tested, and how compliant they are with quarantine. For infected people, their infectiousness and disease prognoses also depend on their age and vaccine status. </p>
<p>COVASIM includes interventions such as testing, contact tracing and quarantine, and public health restrictions that can reduce transmission risk, such as masks and density limits, or the number of contacts. </p>
<p>We calibrated this model using extensive data from Melbourne’s <a href="https://burnet.edu.au/system/asset/file/4241/Burnet_Institute_COVASIM_Resurgence_analysis_2020-09-26.pdf">second wave</a>, then simulated a theoretical Delta variant outbreak. We wanted to know whether previous restrictions would be likely to contain the Delta variant, given improved contact tracing and limited vaccine coverage. </p>
<p>To produce a “Sydney-sized” outbreak, we ran the model with light restrictions until it reached a seven-day average of 30 diagnoses a day. We then applied three policy packages: no additional restrictions, restrictions similar to Melbourne’s Stage 3 + masks, and Stage 4 restrictions.</p>
<h2>Looking at the whole city</h2>
<p>Our second model, <a href="https://www.medrxiv.org/content/10.1101/2021.05.29.21258055v1">MACROMOD</a>, takes the opposite view to COVASIM: it models what happens at the city level, instead of building up from the outcomes of many individual behaviours. </p>
<p>It assumes the epidemic proceeds as a series of periods of exponential growth or decline and is being updated daily as new daily case data becomes available.</p>
<p>MACROMOD was <a href="https://www.medrxiv.org/content/10.1101/2021.05.29.21258055v1">successful</a> in describing Melbourne’s second wave (June to November 2020) and accurately predicted the time to reach zero cases in Melbourne under Stage 4 restrictions. </p>
<h2>What does it predict for Sydney?</h2>
<p>We modelled Sydney’s current outbreak with MACROMOD for 21 days from June 23, when stay-at-home orders began, to July 13. </p>
<p>The impact of the stay-at-home orders was expected to start by July 1. But we couldn’t detect any decrease in the exponential growth in COVID case numbers.</p>
<p>This tells us that despite the fine work done by contact tracers and the NSW public, the high transmissibility of the Delta variant requires a much more vigorous response.</p>
<p>We then projected the model forward to predict the impact of the extended controls on July 9, and a further hypothetical increase similar to Melbourne’s Stage 4 restrictions.</p>
<p>The model suggests that the extended controls may be enough to “flatten the curve”, but are unlikely to contain the outbreak. </p>
<p>Thankfully NSW still has public health levers it could use to get the outbreak under control. We found if Stage 4 restrictions were applied now, the epidemic curve would decline sharply.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/80-vaccination-wont-get-us-herd-immunity-but-it-could-mean-safely-opening-international-borders-162863">80% vaccination won't get us herd immunity, but it could mean safely opening international borders</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/164483/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Margaret Hellard provides guidance to the Victorian Government’s COVID-19 response and received funding from the Victorian Government for the Optimise Study and COVID-19 modelling work.</span></em></p><p class="fine-print"><em><span>Mike Toole receives funding from the Australian National Health and Medical Research Council.</span></em></p><p class="fine-print"><em><span>Nick Scott provides guidance to the Victorian Government’s COVID-19 response and received funding from the Victorian Government for the Optimise Study and COVID-19 modelling work.</span></em></p><p class="fine-print"><em><span>Romesh Abeysuriya provides guidance to the Victorian Government’s COVID-19 response and received funding from the Victorian Government for COVID-19 modelling work.</span></em></p><p class="fine-print"><em><span>Allan Saul does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>It may take until the end of the year to get case numbers close to zero, unless more stringent measures are introduced.Allan Saul, Senior Principal Research Fellow (Honorary), Burnet InstituteMargaret Hellard, Deputy Director (Programs), Burnet InstituteMichael Toole, Professor of International Health, Burnet InstituteNick Scott, Econometrician, Burnet InstituteRomesh Abeysuriya, Senior Research Officer – Computational Epidemic Modelling, Burnet InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1554752021-03-10T19:06:28Z2021-03-10T19:06:28ZMaking a megalodon: the evolving science behind estimating the size of the largest ever killer shark<figure><img src="https://images.theconversation.com/files/388736/original/file-20210310-13-17yzibt.jpg?ixlib=rb-1.1.0&rect=0%2C50%2C8365%2C5860&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Model based on a sculpture by Vlad Konstantinov/CDM Studios</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The giant prehistoric <em>Carcharocles megalodon</em> (or <em>Otodus megalodon</em> for some researchers) was the largest predatory shark to ever swim in Earth’s seas. Scientific evidence points to megalodon having lived between <a href="https://peerj.com/articles/6088/?fbclid=IwAR2zfYl7LxrXBWbY-RG4K7Z36-zjj6U0s3_AvlgHfHt785gTrqMZ7zJF1qA">16 million and 2.6 million years ago</a>, going extinct at the end of the <a href="https://www.britannica.com/science/Pliocene-Epoch">Pliocene Epoch</a> when the world’s oceans were much colder than today’s. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/387152/original/file-20210302-23-1ns3rqn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/387152/original/file-20210302-23-1ns3rqn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=216&fit=crop&dpr=1 600w, https://images.theconversation.com/files/387152/original/file-20210302-23-1ns3rqn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=216&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/387152/original/file-20210302-23-1ns3rqn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=216&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/387152/original/file-20210302-23-1ns3rqn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=271&fit=crop&dpr=1 754w, https://images.theconversation.com/files/387152/original/file-20210302-23-1ns3rqn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=271&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/387152/original/file-20210302-23-1ns3rqn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=271&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Reconstruction of a 16m megalodon.</span>
<span class="attribution"><span class="source">Illustration by Oliver Demuth/Jack Cooper</span></span>
</figcaption>
</figure>
<p>Over the years, <a href="https://www.tandfonline.com/doi/full/10.1080/08912963.2019.1666840">several</a> <a href="https://www.nature.com/articles/s41598-020-71387-y?fbclid=IwAR1VlijIgASwsZSgYLPZs4PuFZ-kHP6PkR5_0vf-u-IL_8Xm0sCwp2CgTNw%3Ca%20href=">research</a> papers have estimated meg’s size. Its teeth are shaped like large, flat triangles with serrated edges — much like the teeth of living <a href="https://www.nationalgeographic.com/animals/fish/facts/great-white-shark">white sharks</a>. White sharks, along with <a href="https://www.britannica.com/animal/mako-shark">mako sharks</a> and the <a href="https://oceana.org/marine-life/sharks-rays/porbeagle-shark">porbeagle shark</a> all belong in the family Lamnidae and are referred to as “lamnids”. </p>
<p>The close similarities between meg teeth and those of living lamnid sharks are strong evidence meg was indeed an ancient kind of lamnid shark. This premise is important, as it forms the basis of how we estimate the size of this ancient giant. </p>
<p>Two museum exhibits recently opened public displays featuring spectacular models of megalodon: one at the Smithsonian Museum of Natural History in Washington DC, and the other at the Western Australian Museum Boola Bardip in Perth. </p>
<p>These models, while both outstanding, don’t depict entirely the same shark. So how was each one made? And what scientific approaches were used? </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/giant-monster-megalodon-sharks-lurking-in-our-oceans-be-serious-53164">Giant monster Megalodon sharks lurking in our oceans: be serious!</a>
</strong>
</em>
</p>
<hr>
<h2>Making the meghead</h2>
<p>The <a href="https://www.smithsonianmag.com/blogs/national-museum-of-natural-history/2019/07/29/megalodon-may-be-extinct-theres-life-size-one-smithsonian/">Smithsonian’s megalodon model</a> is a full-body reconstruction measuring 15 metres. The other, at the Museum Boola Bardip, is a beautifully crafted model of meg’s head. This was built under the direction of one of us (Mikael) and opened to the public in November.</p>
<p>The shape of the “meghead” is similar to a white shark’s head, but has a shorter and much rounder snout. Its colouration features “counter-shading” with a dark back and lighter belly — also similar to white sharks, but less contrasted. The greater this colour contrast, the easier it becomes for underwater predators to go unnoticed by prey.</p>
<p>The meghead’s jaw size was based on multiple teeth from a single ancient shark. These specimens allowed us to scale the body size to correspond with tooth size, as well as to match the widest front tooth of another megalodon found in Cape Range, Western Australia. </p>
<p>The rest of the meghead was then 3D modelled to fit the jaws. The end result was a head that corresponded to a creature roughly 14m in length. This would be the largest meg shark ever found in Western Australia, but not the largest overall.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/388750/original/file-20210310-23-1eahzyk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/388750/original/file-20210310-23-1eahzyk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/388750/original/file-20210310-23-1eahzyk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=444&fit=crop&dpr=1 600w, https://images.theconversation.com/files/388750/original/file-20210310-23-1eahzyk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=444&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/388750/original/file-20210310-23-1eahzyk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=444&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/388750/original/file-20210310-23-1eahzyk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=558&fit=crop&dpr=1 754w, https://images.theconversation.com/files/388750/original/file-20210310-23-1eahzyk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=558&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/388750/original/file-20210310-23-1eahzyk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=558&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The giant megalodon head was scuplted by Vlad Konstantinov for Boola Bardip (WA Museum)</span>
<span class="attribution"><span class="source">Vlad Konstaninov, Mikael Siversson</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Magnificent displays make for great selfies</h2>
<p>The Smithsonian meg model was overseen by Hans-Dieter Sues, a US paleontologist who drew the shark’s outline based on a general lamnid shark body plan. This was then finessed by University of Maryland shark fossil expert Bretton Kent.</p>
<p>After reviewing a small scale model, the full-size model was constructed based on a complete set of meg teeth assembled by Gordon Hubble, another megalodon expert. Measuring a whopping 15m, the final model had to be assembled as modules, as it wouldn’t have made it through the museum’s doors or corridors in one piece. </p>
<p>This model is now suspended by cables from the Smithsonian’s walls and ceiling, positioned strategically so visitors may take selfies from a nearby balcony.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/385495/original/file-20210222-15-qebldd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/385495/original/file-20210222-15-qebldd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/385495/original/file-20210222-15-qebldd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/385495/original/file-20210222-15-qebldd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/385495/original/file-20210222-15-qebldd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/385495/original/file-20210222-15-qebldd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/385495/original/file-20210222-15-qebldd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The 15m-long megalodon model on display at the Smithsonian Museum of Natural History in Washington DC.</span>
<span class="attribution"><span class="source">Hans-Dieter Sues/Smithsonian Museum</span></span>
</figcaption>
</figure>
<h2>Calculating maximum size</h2>
<p>The meghead model in Perth was based on several specific tooth specimens found locally and from overseas, painting a picture of a 14m-long predator. </p>
<p>However, to calculate the species’s <em>maximum</em> size, we first estimated the <a href="https://palaeo-electronica.org/content/2021/3284-estimating-lamniform-body-size?fbclid=IwAR15wOp4rV6j2VNyqxvdqYm4KTna4SdoU_82nBW7wOsywTAdiFcVnXq879g">maximum jaw size possible</a> for Meg and then scaled this up, using the same jaw size-to-body length ratio of living white sharks. </p>
<p>The maximum jaw size of meg can be calculated by scaling up the few known “associated dentitions” (multiple tooth specimens that were found together and came from a single shark) with the widest meg tooth ever found. </p>
<p>Once we did this, the size estimate we reached was between 19–20m. And this is much larger than most other recent estimates.</p>
<h2>The megashark lineage</h2>
<p>Scientists have discovered meg’s teeth to be part of a species continuum known as the <a href="https://www.popsci.com/story/science/megalodon-alive-myth/">megatooth shark lineage</a>. This is based on the discovery of many thousands of fossilised teeth that seem to merge into new shapes over time, pointing to the evolution of new species.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/388470/original/file-20210309-17-i15mi4.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/388470/original/file-20210309-17-i15mi4.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/388470/original/file-20210309-17-i15mi4.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/388470/original/file-20210309-17-i15mi4.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/388470/original/file-20210309-17-i15mi4.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/388470/original/file-20210309-17-i15mi4.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/388470/original/file-20210309-17-i15mi4.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A newly discovered megalodon tooth from near Exmouth, Western Australia. The serrated edge shown here is 145mm long.</span>
<span class="attribution"><span class="source">Geoff Deacon/WA Museum</span></span>
</figcaption>
</figure>
<p>The start of this lineage began in the Danian stage about 63 million years ago, when the first sharks of the genus <em>Otodus</em> appeared. This is why megalodon, belonging to this lineage, is now officially classified as <em>Otodus megalodon</em>. That said, the shark has been placed in various genera, including <em>Carcharocles</em> and <em>Procarcharodon</em>, and continues to be the <a href="https://www.gbif.org/species/144096597">subject of debate</a>.</p>
<p>With an estimated body length of about 4m, the first <em>Otodus</em> sharks in the megatooth lineage would have been smaller than several other sharks living at the time. So how could they have evolved to become the colossus that is meg?</p>
<p>DePaul University professor Kenshu Shimada has <a href="https://www.eurekalert.org/pub_releases/2021-01/tfg-mgb010421.php">suggested</a> meg’s huge size may have had something to do with a strange trait of lamnid sharks, which is that their young eat each other in the womb. </p>
<p>This behaviour, called “intrauterine cannibalism”, provides a ready source of nutrition for growing fetuses and <a href="https://www.tandfonline.com/doi/pdf/10.1080/08912963.2020.1812598">may have driven increased</a> growth in megalodon. That said, it would have also forced mothers to feed more actively, due to increased nutrition demand from the rapidly growing young. </p>
<p>This wouldn’t have helped meg’s survival when global temperatures cooled down about three million years ago. The cold spell would have killed off much of meg’s food sources, eventually triggering its extinction. </p>
<p>In recent years, coastal limestone outcrops in Western Australia have yielded several new exciting megalodon teeth. We hope these will tell us more about the story of meg and its variations which swam through the seas of ancient Australia.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/giant-ancient-sharks-had-enormous-babies-that-ate-their-siblings-in-the-womb-152903">Giant ancient sharks had enormous babies that ate their siblings in the womb</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/155475/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Long receives funding from The Australian Research Council</span></em></p><p class="fine-print"><em><span>Mikael Siversson works for Western Australian Museum. He has received funding for a field trip to Cape Range by the Minderoo Foundation and the Foundation for the WA Museum.</span></em></p>Two museum exhibits, one in the Smithsonian and one in Australia, have opened public displays featuring the spectacular meg. But while both models are mega impressive, they’re not the same. Why?John Long, Strategic Professor in Palaeontology, Flinders UniversityMikael Siversson, Head of Department, Earth & Planetary Sciences, Western Australian MuseumLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1541852021-02-05T03:09:56Z2021-02-05T03:09:56ZWho is (probably) today’s best male tennis player?<figure><img src="https://images.theconversation.com/files/381619/original/file-20210201-23-1wk2nnq.jpg?ixlib=rb-1.1.0&rect=63%2C0%2C3797%2C2822&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock/G Stock Studio</span></span></figcaption></figure><p>When you ask that question, three names come to mind: Roger Federer, Rafael Nadal and Novak Djokovic.</p>
<p>A simple way to compare tennis players is to look at how many grand slam tournaments they have won. That includes victories at the Australian Open, the French Open, Wimbledon in the UK and the US Open. </p>
<p>But this doesn’t take into account how many tournaments they’ve played, which tournaments they’ve played, how far they progressed in each tournament, and who they played against.</p>
<h2>Probably the best player</h2>
<p>My method estimates the <em>probability</em> of a player winning a match in a grand slam tournament. The player with the highest estimated probability of winning a match is then deemed the best player.</p>
<p>Using probability naturally accommodates how many matches and tournaments the player has played, and acknowledges the strong performance of a player who makes a final but doesn’t win the tournament.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/self-entitled-prima-donnas-or-do-they-have-a-point-why-australian-open-tennis-players-find-hard-lockdown-so-tough-153631">Self-entitled prima donnas or do they have a point? Why Australian Open tennis players find hard lockdown so tough</a>
</strong>
</em>
</p>
<hr>
<p>The method builds a statistical model to estimate winning probabilities for each player from <a href="https://www.ultimatetennisstatistics.com/">grand slam data</a>. </p>
<p>By using a technique called regression modelling, it accounts for the fact the winning probability may depend on the quality of the opposition and the grand slam played. For example, some players have preference for hard courts (used at the Australian and US Opens) over clay (used at Roland Garros, home of the French Open).</p>
<p>The opposition quality is inferred from their ranking, and we consider five groups: the top 10, top 20, top 50, top 100 and outside the top 100. These group choices are consistent with terminology used by commentators and pundits.</p>
<p>Another advantage of using a statistical model is that we can make the most of the available data, which is quite small given there are only four grand slam tournaments per year.</p>
<p>For example, if the data support it, the model can enforce a similar pattern of performance against the quality of opposition across tournaments. This is a form of “borrowing of strength” to increase the accuracy of probability estimates from small datasets.</p>
<h2>Oh, the uncertainty</h2>
<p>Using a statistical approach allows us to quantify the uncertainty in probability estimates. Here we communicate uncertainty as an interval (lower and upper limit), that contains the true winning probability with a 95% chance.</p>
<p>So, for example, if the estimated winning probability for a player is 0.77 with an interval of 0.63 to 0.86, it means that our best guess of the winning probability is 0.77. But there is a 95% chance the actual winning probability is between 0.63 and 0.86. This tells us how much uncertainty there is about our best guess.</p>
<p>The amount of uncertainty depends on the number of matches played and the winning probability. There will naturally be more uncertainty if the actual winning probability is around 0.5, that means an even chance of winning or losing.</p>
<p>The results are shown in the figures (below). Each square represents the best probability estimate for Federer, Nadal and Djokovic, and the vertical line represents the uncertainty interval.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/381595/original/file-20210201-15-nonavb.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graph for the Australian Open" src="https://images.theconversation.com/files/381595/original/file-20210201-15-nonavb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381595/original/file-20210201-15-nonavb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381595/original/file-20210201-15-nonavb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381595/original/file-20210201-15-nonavb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381595/original/file-20210201-15-nonavb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381595/original/file-20210201-15-nonavb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381595/original/file-20210201-15-nonavb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Chris Drovandi</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/381596/original/file-20210201-23-1ioyjd7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graph for the French Open" src="https://images.theconversation.com/files/381596/original/file-20210201-23-1ioyjd7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381596/original/file-20210201-23-1ioyjd7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381596/original/file-20210201-23-1ioyjd7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381596/original/file-20210201-23-1ioyjd7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381596/original/file-20210201-23-1ioyjd7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381596/original/file-20210201-23-1ioyjd7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381596/original/file-20210201-23-1ioyjd7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Chris Drovandi</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/381597/original/file-20210201-23-167z5qb.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graph for Wimbledon" src="https://images.theconversation.com/files/381597/original/file-20210201-23-167z5qb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381597/original/file-20210201-23-167z5qb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381597/original/file-20210201-23-167z5qb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381597/original/file-20210201-23-167z5qb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381597/original/file-20210201-23-167z5qb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381597/original/file-20210201-23-167z5qb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381597/original/file-20210201-23-167z5qb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Chris Drovandi</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/381598/original/file-20210201-17-dpi9bp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graph for US Open" src="https://images.theconversation.com/files/381598/original/file-20210201-17-dpi9bp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381598/original/file-20210201-17-dpi9bp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381598/original/file-20210201-17-dpi9bp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381598/original/file-20210201-17-dpi9bp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381598/original/file-20210201-17-dpi9bp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381598/original/file-20210201-17-dpi9bp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381598/original/file-20210201-17-dpi9bp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Chris Drovandi</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>The winner is …</h2>
<p>For the Australian Open, there is evidence to suggest that Djokovic is the top-performing male player.</p>
<p>But given the overlapping uncertainty intervals in the probability estimates with the other players, it is difficult to definitively state this.</p>
<p>It is difficult to separate the three players at the US Open. Wimbledon appears to be the tournament that Federer shines the most relative to the other players, but again there is significant overlap in the intervals.</p>
<p>Although there is some evidence that Nadal is the worst-performing player at the Australian Open and at Wimbledon (which is played on grass courts), he is the undisputed champion at the French Open.</p>
<p>Incredibly, Nadal has an estimated probability around 0.93 to win a game against a top 10 player at this tournament. This clearly shows Nadal’s dominance on clay courts. The French Open is a relative Achilles’ heel for Federer.</p>
<p>The analysis reveals some other interesting results. For example, the results suggest Nadal performs similarly against top 20 and top 50 players, as does Djokovic.</p>
<p>But there is generally a big drop in winning probability against top 10 players.</p>
<p>Apart from some cases (Nadal at the French Open, Djokovic at the Australian Open and Federer at Wimbledon), the chance that one of these champion players beats a top 10 player in a grand slam isn’t much better than a coin toss.</p>
<h2>And the best player is …</h2>
<p>On the women’s side, it’s widely accepted that Serena Williams is the top player in the modern era, and possibly of all time. Williams has won the most grand slams of any current player, male or female.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/all-that-slipping-and-sliding-on-tennis-courts-prevents-injuries-a-biomechanics-expert-explains-how-106938">All that slipping and sliding on tennis courts prevents injuries: a biomechanics expert explains how</a>
</strong>
</em>
</p>
<hr>
<p>For the men it’s less so clear. So in response to the question of who is the best male tennis player of the modern era, the answer is “it depends”.</p>
<p>If pressed for an answer, it’s hard to go past Rafael Nadal. He has dominated a grand slam (French Open) unlike the other players, while remaining competitive in the other three slams.</p>
<p>A more comprehensive analysis would consider data from all tournaments, not just grand slams, and this would help to reduce uncertainty in the winning probability estimates.</p>
<p>It should also be noted that these are retrospective winning probability estimates, and cannot be used to predict outcomes for future tournaments. Predictive statistical models would focus on more recent tennis data.</p><img src="https://counter.theconversation.com/content/154185/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Drovandi is a Professor of Statistics at the Queensland University of Technology (QUT), and is a Program Director in the QUT Centre for Data Science. He is an Associate Investigator of the Australian Research Centre of Excellence for Mathematical and Statistical Frontiers (ACEMS). He receives funding from the Australian Research Council. </span></em></p>With the Australian Open about to start this year’s grand slam series, a crunch of the data from past performances gives a hint at who is the current best male player, possibly.Christopher Drovandi, Professor of Statistics, Queensland University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1541452021-02-01T18:05:36Z2021-02-01T18:05:36ZCybersecurity risks and how to manage them<figure><img src="https://images.theconversation.com/files/381354/original/file-20210129-21-1s3pdxn.jpg?ixlib=rb-1.1.0&rect=22%2C241%2C3007%2C2068&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cybersecurity risks evolve rapidly, and are everywhere.</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/xxn48oa73sM">Joshua Gandara/Unsplash </a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The <a href="https://theconversation.com/the-sunburst-hack-was-massive-and-devastating-5-observations-from-a-cybersecurity-expert-152444">Sunburst attack</a> uncovered in December 2020 illustrates the magnitude of the cybersecurity challenge. Hackers were able to breach some of the United States’ top government agencies as well as those of other organisations around the world by compromising updates from one of their software suppliers, SolarWinds. Organisations might make use of hundreds if not thousands of <a href="https://www.forbes.com/sites/jwebb/2018/02/28/how-many-suppliers-do-businesses-have-how-many-should-they-have/?sh=6ec4b93d9bb7">third-party suppliers and contractors</a> through which they could be breached.</p>
<p>While many of these involve third-party suppliers and contractors in the IT realm, in some cases breaches can be caused by third parties that one might not expect. For example, it was reported in 2017 that a casino in Las Vegas was breached through an <a href="https://www.washingtonpost.com/news/innovations/wp/2017/07/21/how-a-fish-tank-helped-hack-a-casino/">Internet-connected fish tank</a>. Similarly, in 2014 <a href="https://www.wsj.com/articles/BL-DGB-32638">Target was breached through its air-conditioning supplier</a>. Organisations frequently take on new third-party suppliers and contractors, further compounding the challenge. </p>
<p>The rapidly evolving nature of the risk makes it difficult to assess, and all organisations are currently struggling with how to manage cybersecurity risk. New threat actors and types of attacks regularly emerge. For example, we are seeing the advent of AI-enabled attacks. In one highly publicised instance, cybercriminals tricked an employee into transferring money to them by <a href="https://www.wsj.com/articles/fraudsters-use-ai-to-mimic-ceos-voice-in-unusual-cybercrime-case-11567157402">using AI to imitate the CEO’s voice</a>.</p>
<p>Current approaches to managing cybersecurity risk have significant shortcomings. Risk assessments tend to rely on “risk matrices”, which use a grid to compare the likelihood of the risk and the severity of the impact. The numerical values assigned to the likelihood and severity ratings tend to be ambiguous, meaning that they can assign the same numerical values to threats that are quantitatively quite different . This can cause organisations to incorrectly prioritise threats and thus allocate resources in a suboptimal manner.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/381144/original/file-20210128-17-12zdncj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381144/original/file-20210128-17-12zdncj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=288&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381144/original/file-20210128-17-12zdncj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=288&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381144/original/file-20210128-17-12zdncj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=288&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381144/original/file-20210128-17-12zdncj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=361&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381144/original/file-20210128-17-12zdncj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=361&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381144/original/file-20210128-17-12zdncj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=361&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A risk matrix, a traditional tool to assess risks by multiplying quantitative values associated to the likelihood of the risk and the severity of the impact.</span>
<span class="attribution"><span class="source">Elsa Couderc</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<h2>A role for cyber insurance</h2>
<p>Increased use of <a href="https://ieeexplore.ieee.org/abstract/document/7349090">cyber insurance could significantly improve cybersecurity risk management</a>. It helps organisations by transferring the risk to <a href="https://www.investopedia.com/ask/answers/051915/how-does-insurance-sector-work.asp">insurance providers</a>. Quite importantly, it could also incentivize organisations to improve their cybersecurity levels, through insurers offering customers a discount in exchange for improving security measures.</p>
<p>Yet cyber insurance is still <a href="https://www2.deloitte.com/us/en/insights/industry/financial-services/cyber-insurance-market-growth.html">underdeveloped for a number of reasons</a>. Insurers face difficulty in accurately assessing an organisation’s cybersecurity risk. Unlike in other domains that have similarly elevated levels of risk – such as pandemics – there is limited historical data to draw on. A contributing factor to this lack of data is that organisations are reluctant to disclose that they have been attacked due to reputational concerns. Moreover, an organisation’s risk profile at the time an insurance policy is issued may differ considerably several months later. </p>
<p>These issues are compounded by an acute shortage of experienced cybersecurity underwriters, whose job it is to decide whether to issue a policy to a prospective client.</p>
<p>Another challenge is “accumulation risk”, in which a single incident can spread to other parts of an insurer’s portfolio. It is particularly difficult to evaluate accumulation risk in the cyber realm. In the physical world, a hurricane or other natural disaster may trigger a surge in claims, but these claims are limited to a particular geographic area. In cyberspace, a cyberattack can result in claims around the world. For example, the WannaCry ransomware attack infected some <a href="https://www.bbc.co.uk/news/world-39919249">200,000 computer systems in 150 countries</a>, severely disrupting major organisations such as FedEx and the UK’s National Health Service.</p>
<p>A related issue is “systemic risk”, in which one incident could cause a cascading failure that triggers the collapse of an entire system. For example, a cyberattack that takes down the power grid will impact sectors ranging from transport to communications to healthcare.</p>
<h2>Improving our understanding of cyber risk</h2>
<p>To address these issues, in our <a href="https://www.routledge.com/Security-Risk-Models-for-Cyber-Insurance/Insua-Baylon-Vila/p/book/9780367339494">new book</a> we propose a series of models aimed at helping both organisations and insurers manage cybersecurity risk. They make use of a methodology known as <a href="https://arxiv.org/abs/2007.02613">adversarial risk analysis</a>, which makes it possible to better assess the risk that different threat actors pose to an organisation.</p>
<p>These models allow insurers to automatically adjust premiums in response to changes in an insured organisation’s cybersecurity risk. They draw on data provided by third party companies that gather real time information about organisations’ IT infrastructure, security products, and other factors to get a clearer picture of an organisation’s cybersecurity risk at any given point in time. These third-party companies include firms such as <a href="https://www.ft.com/content/1cfd5d28-c26f-11e6-81c2-f57d90f6741a">SecurityScorecard, Blueliv and BitSight</a>.</p>
<p>One of the models makes it possible to better understand accumulation risk. It does so by breaking out different market segments as separate components in order to isolate, understand, and analyse the accumulation effect of a cyberattack on a given market segment.</p>
<p>The book also describes how some insurers are moving beyond merely selling insurance to assisting customers in <a href="https://www.wsj.com/articles/cyber-insurers-get-tough-on-risk-assessments-amid-coronavirus-pandemic-11589794201">improving their cybersecurity readiness</a>. For example, they might share information on security vulnerabilities, assess customers’ IT infrastructure, or help them implement penetration testing of their IT systems and phishing-awareness campaigns aimed at their employees. In addition, they may support customers in responding to cyberattacks, providing crisis management and legal assistance, and helping them get back to business. This is typically accomplished <a href="https://insuranceblog.accenture.com/partnerships-can-help-carriers-optimize-the-cyber-insurance-opportunity">through partnerships</a> with cybersecurity companies, public relations firms and legal firms.</p>
<p>These developments can play an important role in cybersecurity risk management, helping make it possible to create a virtuous cycle where cyber insurance fosters an increase in cybersecurity worldwide.</p>
<hr>
<p><em>This article is based in part on our latest book, <a href="https://www.routledge.com/Security-Risk-Models-for-Cyber-Insurance/Insua-Baylon-Vila/p/book/9780367339494">Security Risk Models for Cyber Insurance</a>, published by Routledge/Taylor & Francis. It grew out of a two-year project funded by the European Union under Horizons 2020, <a href="https://www.cybeco.eu/">CYBECO</a> (Supporting Cyber Insurance from a Behavioral Choice Perspective).</em></p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/310261/original/file-20200115-134768-1tax26b.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/310261/original/file-20200115-134768-1tax26b.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=158&fit=crop&dpr=1 600w, https://images.theconversation.com/files/310261/original/file-20200115-134768-1tax26b.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=158&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/310261/original/file-20200115-134768-1tax26b.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=158&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/310261/original/file-20200115-134768-1tax26b.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=198&fit=crop&dpr=1 754w, https://images.theconversation.com/files/310261/original/file-20200115-134768-1tax26b.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=198&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/310261/original/file-20200115-134768-1tax26b.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=198&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em>Created in 2007 to help accelerate and share scientific knowledge on key societal issues, the AXA Research Fund has been supporting nearly 650 projects around the world conducted by researchers from 55 countries. To learn more, visit the site of the <a href="https://www.axa-research.org">Axa Research Fund</a> or follow on Twitter <a href="https://twitter.com/axaresearchfund?lang=fr">@AXAResearchFund</a></em></p><img src="https://counter.theconversation.com/content/154145/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Caroline Baylon works for AXA. This project was funded by the European Union under the Horizons 2020 programme. </span></em></p><p class="fine-print"><em><span>David Rios Insua is supported by the AXA Research Fund and the CYBECO H2020 European project.</span></em></p>Cybersecurity risks are evolving rapidly. How can they be more effectively assessed and managed ?Caroline Baylon, Security Research and Innovation Lead, AXA and Research Affiliate, Centre for the Study of Existential Risk, University of CambridgeDavid Rios Insua, Member of the ICMAT, AXA-ICMAT Chair in Adversarial Risk Analysis and Member of the Spanish Royal Academy of Sciences, Instituto de Ciencias Matemáticas (ICMAT-CSIC)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1515622020-12-23T14:54:22Z2020-12-23T14:54:22ZImproving building ventilation can help us control the spread of COVID-19 during the winter months<figure><img src="https://images.theconversation.com/files/375691/original/file-20201217-13-qrtqug.jpg?ixlib=rb-1.1.0&rect=16%2C0%2C5422%2C3470&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The risk of transmitting COVID-19 is much higher indoors due to proximity to other people and building ventilation systems.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>As predicted, we are in the middle of second wave of COVID-19. As of Dec. 23, the world has <a href="https://coronavirus.jhu.edu/map.html">seen over 78 million confirmed cases and 1.7 million deaths</a>. </p>
<p>One of the few successes to emerge has been the creation of COVID-19 vaccines in record time. But <a href="https://ottawacitizen.com/news/local-news/vaccine-an-encouraging-milestone-but-theres-still-work-ahead-says-etches">vaccination will not provide immediate relief</a>. </p>
<p>There are many unanswered questions about the efficacy of the vaccines. For instance, vaccine studies mostly tracked how many of the individuals that were vaccinated became sick. It is not known if the vaccinated individuals can still carry the virus asymptomatically; vaccinated people don’t show symptoms, but some may <a href="https://www.nytimes.com/2020/12/08/health/covid-vaccine-mask.html">continue to have virus in the nose and throat that can replicate and spread</a>. We also do not know about the chances of reinfection or long-term immunity. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1338511835310546947"}"></div></p>
<p>Infection with COVID-19 comes with a risk of death and puts strain on our health-care system, but there is also <a href="https://www.mayoclinic.org/diseases-conditions/coronavirus/in-depth/coronavirus-long-term-effects/art-20490351">a risk of long-term health effects</a>. The bottom line is that we cannot let our guard down: we need to continue wearing masks, keep our physical distance, wash our hands, and avoid crowds and indoor events in poor ventilated areas.</p>
<p>As the vaccine is distributed, we might find ourselves relaxing our guard before it is safe to do so. And as the weather grows increasingly colder, reducing our options for outdoor activities and gatherings, we need to consider how the disease spreads indoors and the importance of ventilation.</p>
<h2>Avoiding crowded indoors</h2>
<p>The evidence for <a href="https://first10em.com/covid-19-is-spread-by-aerosols-an-evidence-review/">aerosol transmission is overwhelming</a>. Three of the most important factors that determine the risk of exposure are proximity to people, duration of the exposure and the quality of the air. When the three are combined, <a href="https://www.ft.com/content/2418ff87-1d41-41b5-b638-38f5164a2e94">the risk is higher</a>, as seen in numerous superspreader events.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-few-superspreaders-transmit-the-majority-of-coronavirus-cases-139950">A few superspreaders transmit the majority of coronavirus cases</a>
</strong>
</em>
</p>
<hr>
<p>COVID-19 <a href="http://doi.org/10.1126/science.abf0521">spreads through inhalation of the virus</a>. An infected person breathes out aerosols that can remain suspended in the air <a href="https://www.cdc.gov/coronavirus/2019-ncov/more/scientific-brief-sars-cov-2.html">for up to three hours</a>. Transmission indoors can be around <a href="https://doi.org/10.1111/ina.12766">20 times higher than outdoors</a>. </p>
<p>We have to think about SARS-CoV-2, the virus that causes COVID-19 <a href="https://time.com/5883081/covid-19-transmitted-aerosols/">spreading like cigarette second-hand smoking</a> in a closed space. Imagine being indoors where smoking is permitted: the exhaled smoke can spread in poorly ventilated spaces. The amount of particles inhaled close to the source is higher, but, with time, the smoke will fill the whole room and everybody will breathe the contaminated air.</p>
<p>Indoor transmission by aerosols has been <a href="https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/how-covid-spreads.html">recognized by the U.S. Centers for Disease Control and Prevention</a> and the <a href="https://www.cbc.ca/news/health/coronavirus-canada-aerosol-transmission-covid-19-1.5789906">Public Health Agency of Canada</a>. The World Health Organization recommends <a href="https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public">avoiding indoor spaces whenever possible and ensuring proper ventilation in the fight against COVID-19</a>. </p>
<p>We need to take these recommendations seriously during the holiday season: we need to <a href="http://doi.org/10.1001/jamanetworkopen.2020.31756">reduce the number of close contacts</a>, in particular in indoor settings, wear masks and ventilate the rooms.</p>
<h2>Modelling ventilation indoors</h2>
<p>At present, my research team is interested in different aspects of indoor ventilation. We are combining building information modelling and <a href="https://sustain.sce.carleton.ca/">indoor viral spread models</a> to study different strategies to return to indoor gatherings and address potential future outbreaks.</p>
<p>One example we used was the site of a COVID-19 outbreak associated with the use of <a href="https://www.doi.org/10.3201/eid2607.200764">air conditioning in a restaurant in Guangzhou, China</a>. We showed how the airflow produced by the ventilation system affected 10 different individuals. Our team used the floor plans of the restaurant and built a model that can easily be adapted for different factors, such as different positioning of the ventilation sources.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/QZfevexabPk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A video showing different models of aerosol diffusion through ventilation in a restaurant in Guangzhou, China.</span></figcaption>
</figure>
<p>Modelling and simulating indoor ventilation is important: we need to find out which factors — like circulating fresh air or using high-quality air filters — are likely to reduce transmission risk. Simulated virtual environments can be quite informative, as it’s not possible to run experiments with people and COVID-19. </p>
<p>In addition, there is limited information about how infectious SARS-CoV-2 is. Although we know that <a href="https://doi.org/10.1016/S2666-5247(20)30172-5">people shed different amounts of the virus</a>, we don’t know how much virus someone has to inhale to become sick. Using a simulated virtual environment can be useful to conduct different experiments.</p>
<p>The models we constructed allow us to study different scenarios. For instance, we include <a href="http://jv.colostate.edu/masktesting/">different types of fabric</a> used for the masks by different individuals as well as the different fitting positions of the masks, which can influence <a href="http://doi.org/10.1001/jamainternmed.2020.4221">the amount of virus transmitted or inhaled</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/9D6nE-eY9js?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Using a game to study the effects of mask-wearing.</span></figcaption>
</figure>
<p>The building models can easily adjust different factors for analysis, such as different physical arrangements of people (and their relative physical distance), <a href="https://www.ashrae.org/file%20library/technical%20resources/ashrae%20journal/2020journaldocuments/72-74_ieq_schoen.pdf">various ventilation methods</a>, a range of air qualities and even the use of portable HEPA filters to reduce <a href="https://www.usatoday.com/in-depth/graphics/2020/10/18/improving-indoor-air-quality-prevent-covid-19/3566978001/">the probability of being infected</a>.</p>
<p>And now that there are vaccines, we’ll need to factor in how the vaccination process will affect disease transmission. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/7zkrVQy45M4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Integrating a simulation model with a Geographical Information System showing the spread of COVID-19 in Ontario.</span></figcaption>
</figure>
<p>In the meantime, we need to remain vigilant, and focus on the <a href="https://doi.org/10.1016/j.puhe.2020.03.007">social aspects of the pandemic</a>: online misinformation, social behaviours and public health communication strategies. These are important for all air-transmitted diseases (seasonal flu, colds), including any future pandemics.</p><img src="https://counter.theconversation.com/content/151562/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gabriel Wainer receives funding from NSERC and collaborates with DRDC (DND).</span></em></p>Studying how SARS-CoV-2, the virus that causes COVID-19, travels through indoor air spaces can help reduce transmission risk.Gabriel Wainer, Professor, Systems and Computer Engineering, Carleton UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1521532020-12-17T10:41:55Z2020-12-17T10:41:55ZCoronavirus vaccines: how will we know when life can go back to normal?<p>The first people have begun to receive vaccines in the UK and US as part of <a href="https://www.bbc.co.uk/news/uk-55227325">mass vaccination campaigns</a> to immunise people against COVID-19. Excitement is building – finally, the end of the coronavirus crisis is in sight. </p>
<p>Since early December, elderly patients and health workers in 50 hospitals across the UK have been <a href="https://www.bbc.co.uk/news/uk-55227325">given the vaccine</a> developed by <a href="https://www.nature.com/articles/d41586-020-03166-8">Pfizer and BioNTech</a>. This vaccine has also been granted emergency use authorisation by the <a href="https://www.fda.gov/news-events/press-announcements/fda-takes-key-action-fight-against-covid-19-issuing-emergency-use-authorization-first-covid-19">Food and Drug Administration</a> in the US and is currently being administered to the first priority groups. </p>
<p>The popular assumption is that the Pfizer/BioNTech vaccine and the others in development will reduce severity of the disease, reduce transmission of the SARS-CoV-2 virus, provide population immunity and get us back to the normality of the pre-COVID era. </p>
<p>While scientists, including myself, are very excited at the prospect of an effective vaccine and the prospect of returning to normality, it is important to temper this enthusiasm with caution. Several questions still remain about how much protection an effective vaccine offers, to whom and for how long.</p>
<h2>A bumper crop of vaccines</h2>
<p>Starting a mass vaccination programme is an important first step towards ending this pandemic. And it has come relatively quickly. Producing an effective vaccine against an infectious disease is a long process that in the past has usually taken many years. </p>
<p>The development of the COVID-19 vaccine this year, on the other hand, has been extraordinarily fast. It has shown how quickly scientific development can be achieved via collaborative hard work, and how much the will can produce the means. During 2020, <a href="https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html">61 vaccines have been developed</a>, with a number of these in <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)32623-4/fulltext">clinical trials</a>, and some reporting a more than 90% efficacy rate against COVID-19. There is no doubt that it has been a year of remarkable progress. </p>
<p>But even when widely used, the efficacy of vaccines has not historically been guaranteed. Only one disease, smallpox, has ever been truly eradicated – and achieving that took more than 200 years. Meanwhile, we continue to live with diseases such as polio, tetanus, measles and tuberculosis, with the wide use of vaccines helping protect vulnerable cohorts. So we don’t yet know if immunisation will get rid of COVID-19 for good. </p>
<h2>Learning from the roll-out</h2>
<p>There are other questions for which we also need answers. </p>
<p>The efficacy of the vaccine during a clinical trial is measured by how many cases occurred in the vaccinated group. To ascertain the efficacy across the population, further details are needed on whether these cases are mostly mild or whether they include significant numbers of moderate and severe cases. </p>
<p>We also need clarity on transmission – will the vaccine prevent asymptomatic people or those with very mild symptoms of COVID-19 from spreading the virus? The <a href="https://www.nytimes.com/interactive/2020/12/04/world/europe/europe-covid-deaths.html">recent resurgence of the virus</a> suggests that transmission of COVID-19 is not slowing down, and that we need a transmission-blocking vaccine to truly bring about the end of the pandemic. A severity-reducing vaccine will prevent deaths and the overwhelming of hospitals, but not stop the spread. </p>
<p>Whether the Pfizer/BioNTech vaccine or the other vaccines in late-stage trials can achieve this is difficult to assess, because this would require routinely testing all trial participants as well as their contacts – this is difficult to do in such large numbers. Instead, as the vaccines roll out in the UK and the US, the after-effects will be closely watched and we will get a better feel of the overall impact. </p>
<p>Another aspect that we need to understand is how well the vaccine may work across different age, population and risk cohorts. Finally, there is the question of how long immunity will last. People need to be watched and tracked three, six and 12 months after receiving the vaccine to assess the different levels of protective antibodies in their blood.</p>
<h2>Modelling</h2>
<p>We can’t wait a year to find out the answer to all these questions. This is where mathematical modelling of possible epidemic trajectories with different vaccination scenarios can be helpful. </p>
<p>Mathematical modelling has been at the forefront of policy decision-making worldwide throughout the pandemic, as it allows us a way to assess the potential effects of both <a href="https://www.nature.com/articles/s41586-020-2405-7">non-pharmaceutical interventions</a> – such as <a href="https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(20)30133-X/fulltext">lockdown</a> or different <a href="https://www.thelancet.com/journals/lanchi/article/PIIS2352-4642(20)30250-9/fulltext">test, trace</a> and <a href="https://science.sciencemag.org/content/368/6491/eabb6936">isolate</a> strategies – and pharmaceutical interventions <a href="https://pubmed.ncbi.nlm.nih.gov/32576461/">such as a vaccine or antiviral treatment</a>.</p>
<p>Modelling can help us explore what the effect of different levels of vaccine efficacy and coverage (percentage of people vaccinated) will be on the reproduction number R (which indicates the rate of transmission in the population) or on the number of COVID-19 cases and deaths. We can also explore the potential differences between a vaccine that reduces severity, one that blocks transmission and one that does both. We can model how these outcomes change if we combine different levels of coronavirus restrictions with different vaccines.</p>
<p>Together with colleagues, I am working on answering such questions and exploring whether vaccination against COVID-19 will stave off third and subsequent waves. </p>
<p>For now, we are still very early in the vaccination campaigns and we do not yet even have published results from our models. So unfortunately it’s still too difficult to say whether life will go back to normal next year. </p>
<p>The good news is that by combining the results from the recently started mass vaccination campaigns in the UK and the US with mathematical modelling, we will soon have some of the answers we need. </p>
<p>We should all be excited at the prospect of an effective vaccine, but we should also be wary of the fact that we are not there yet. And until we get there, we need to follow <a href="https://www.who.int/westernpacific/emergencies/covid-19/information/transmission-protective-measures#:%7E:text=COVID%2D19%20transmission%20and,touched%20objects%20and%20surfaces.">the COVID-19 safety measures</a> to protect ourselves and others.</p><img src="https://counter.theconversation.com/content/152153/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jasmina Panovska-Griffiths does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Here’s what we still need to find out before we can know when we’ll be able to return to our pre-coronavirus ways.Jasmina Panovska-Griffiths, Senior Research Fellow and Lecturer in Mathematical Modelling, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1507062020-12-07T18:16:31Z2020-12-07T18:16:31ZHow mathematics can help us understand tumor growth<figure><img src="https://images.theconversation.com/files/372788/original/file-20201203-23-1t7ysmr.jpeg?ixlib=rb-1.1.0&rect=18%2C30%2C2026%2C1502&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A melanoma, a malignant tumor of the pigmentary system of the skin, magnified 40 times.</span> <span class="attribution"><a class="source" href="https://librepathology.org/wiki/File:Melanoma40x.JPG">J Wisell</a></span></figcaption></figure><p>In our daily life, we unfortunately have become used to seeing images of tumors and melanomas. You may have noticed that they’re are not entirely symmetric. This asymmetry is useful to doctors in their diagnoses, but why are they asymmetric?</p>
<p>Instinctively, we think that symmetric objects are most often found in nature, but perhaps assymetry is even more common. To complicate things, the same object may sometimes be symmetric and sometimes not. Take soap bubbles for example. When they are small, they seem perfectly symmetric, but when we increase their radius, we see that symmetry is broken: the soap bubble is not perfectly round anymore. This phenomenon is due to the presence of physical effects such as wind and gravity. Therefore, we may affirm that the final shape of the soap bubble is caused by several factors, and the effect of each of those cannot be ignored.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/372796/original/file-20201203-19-1ow2ma1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/372796/original/file-20201203-19-1ow2ma1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/372796/original/file-20201203-19-1ow2ma1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/372796/original/file-20201203-19-1ow2ma1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/372796/original/file-20201203-19-1ow2ma1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/372796/original/file-20201203-19-1ow2ma1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/372796/original/file-20201203-19-1ow2ma1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A large soap bubble becomes asymmetrical.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Big_soap_bubble_of_irregular_shape_in_Paris.jpg">Basile Morin</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The same happens for cancer growth: the asymmetric shape is due to different biological phenomena. To understand what those phenomena are is still at the center of ongoing research in biology and medicine. Mathematics may give a valuable insight on different aspects of tumor growth. By constructing mathematical models and investigating their solutions, we <a href="https://doi.org/10.1142/S0218202508002796">distinguish</a> between various possible aspects in the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1303573/">mechanisms of tumor growth</a>. This may be useful in developing effective treatments and providing biologists and doctors with complementary information.</p>
<h2>Can we model how a tumor grows?</h2>
<p>The shape of a tumor is the result of several interactions between tumor cells, healthy cells, molecules and other tissues. To mathematically describe its evolution from a global point of view, one can use a “diffusion equation”. Diffusion equations are good mathematical tools in such a context because they allow to describe the global effects of a physical process which takes place on a much smaller scale.</p>
<p>In general, the process at small scale is diffusion: a net movement of any object (for instance atoms or molecules) from a region of high concentration to a region of lower concentration. One example of such behavior can be the evolution of the temperature (or heat) in a room. We know, by experience, that if we heat one small part of our room, soon the heat will spread over to the rest of it. Nowadays we know that this thermal equilibrium is reached because the atoms and molecules composing the air are moving randomly and disorderly. This motion, called Brownian motion, is named after Robert Brown, an English botanist who first described it in 1827 while observing the movement of pollen particles in water. Interestingly, diffusion equations in mathematics were already studied independently since 1822, when Joseph Fourier introduced his landmark heat equation.</p>
<p>However, the connection between the small scale (Brownian motion) and the global effect of thermal equilibrium was only pointed out by Albert Einstein and <a href="https://fr.wikipedia.org/wiki/Marian_Smoluchowski">Marian Smoluchowski</a> in 1905.</p>
<figure> <img src="https://lh6.googleusercontent.com/BjkSqo2RxJYNpj9YYIjPmmXz1sTYlImXjeJg-K8QUErjj7D8fMkFGSK0j00hBWPoFCSQ4FzIk4FAEB9jofK3sxiT6Qcdvka2DopCjeDnvyY17TNT18ZA=w1280"> <figcaption> Simulation of the Brownian motion with 1,000 particles. Initially the particles are concentrated in the square region in the center and they spread over all the available space. In red, the trajectory of one single particle. ([N. Pouradier Duteil](https://sites.google.com/site/nastassiapouradierduteil/))</figcaption> </figure>
<h2>Different types of diffusion and different models</h2>
<p>Einstein described a particular type of diffusion, nowadays called the “linear diffusion”. It is characterized by its “mean squared displacement”, an average of how much the particles move in time. The “mean squared displacement” is linear in time, meaning that, on average, if we wait 5 units in time, the particles will move of √5 units in space. The linearity here is between the quantity of time and the square of the quantity of space.</p>
<p>This is not the only possible diffusion and other types have been used and studied, their classification often depending on this notion of <a href="https://en.wikipedia.org/wiki/Mean_squared_displacement">“mean squared displacement”</a>. For instance, in the “superdiffusion”, the particles are allowed to “make jumps” (nowadays called Lévy walks) and so to move more in space. This behavior is not only common for molecules but has been observed in animals. For example, it describes well the the <a href="https://www.pnas.org/content/109/19/7169">foraging strategies of an Albatros</a>. We may notice the differences between the trajectories of a Brownian motion and those of the albatros. In the former the particle stays close to its initial position while in the latter the albatros makes long movements (Lévy jumps).</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/372797/original/file-20201203-23-1vvni2.gif?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/372797/original/file-20201203-23-1vvni2.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=671&fit=crop&dpr=1 600w, https://images.theconversation.com/files/372797/original/file-20201203-23-1vvni2.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=671&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/372797/original/file-20201203-23-1vvni2.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=671&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/372797/original/file-20201203-23-1vvni2.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=844&fit=crop&dpr=1 754w, https://images.theconversation.com/files/372797/original/file-20201203-23-1vvni2.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=844&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/372797/original/file-20201203-23-1vvni2.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=844&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Foraging track of a black-browed albatross.</span>
<span class="attribution"><a class="source" href="https://www.pnas.org/content/109/19/7169/tab-figures-data">[Nicolas E. Humphries et coll](https://www.pnas.org/content/109/19/7169.abstract), PNAS 2012, PNAS License to Publish</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>One of the main advantages in mathematics is that, often, similar techniques and concepts can be adapted to describe different situations in nature. This is the case of parabolic equations, which are a generalization of the above diffusion equations, and are used to model a big variety of phenomena such as the oscillation of prices of the <a href="https://en.wikipedia.org/wiki/Black%E2%80%93Scholes_equation">stock market</a> or the evolution of a material undergoing a phase transition, for example the melting of ice into water. The common feature in the phenomena described by parabolic equations is always the description of a global effect arising from a process on a smaller scale.</p>
<h2>The shape of a tumor</h2>
<p>Assuming that every cell is (more or less) moving randomly we may describe the evolution of the cell density in space (number of cells per volume unit) by a diffusion equation. However, we will not obtain an asymmetric evolution by considering only the cell density. Indeed, a feature of diffusion equations is exactly to make the evolution more symmetric, in an effect similar to the thermal equilibrium explained above.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/372800/original/file-20201203-19-1gsl7qv.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/372800/original/file-20201203-19-1gsl7qv.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/372800/original/file-20201203-19-1gsl7qv.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=495&fit=crop&dpr=1 600w, https://images.theconversation.com/files/372800/original/file-20201203-19-1gsl7qv.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=495&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/372800/original/file-20201203-19-1gsl7qv.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=495&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/372800/original/file-20201203-19-1gsl7qv.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=622&fit=crop&dpr=1 754w, https://images.theconversation.com/files/372800/original/file-20201203-19-1gsl7qv.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=622&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/372800/original/file-20201203-19-1gsl7qv.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=622&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Simulation of the cell density of a tumor (the whiter the denser). In the center we can observe cells dying of lack of nutrients.</span>
<span class="attribution"><a class="source" href="https://hal.archives-ouvertes.fr/hal-00931399">Benoît Perthame, Min Tang and Nicolas Vachelet, M3AS</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>To obtain asymmetries, we need more elements in the model, but which effect has to be added? This is when mathematics can be useful to biology as we mathematicians can test hypotheses. Indeed, by adding different elements to the model, we can simulate different aspects of the tumor growth and better understand its mechanisms. Such elements may be, for instance, the presence of nutrient (generally oxygen or glucose brought by blood vessels), which presence is again modeled by a diffusion equation describing how the tumor consumes the nutrients, or the presence of an external pressure applied by other tissues, for example an organ by one side of a tumor. By including these features in the model, we can obtain shapes as those in the above figure, closer to what we see in the real world.</p>
<hr>
<p><em>The Ile-de-France Region funds important research projects is committed through the Paris Region Phd research-training programme by co-financing 100 doctoral contracts by 2022. For more information, please visit <a href="http://www.iledefrance.fr/education-recherche">iledefrance.fr/education-recherche</a>.</em></p><img src="https://counter.theconversation.com/content/150706/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nikita Simonov a reçu des financements de Dim Math Innov, Région Île-de-France (<a href="https://www.dim-mathinnov.fr/fr/">https://www.dim-mathinnov.fr/fr/</a>).</span></em></p>To better understand how cancer tumors grow, mathematicians use diffusion models.Nikita Simonov, Post-doctorant au Centre de Recherche en Mathématiques de la Décision, labellisé Domaine d’Intérêt Majeur par la Région Île-de-France,, Université Paris Dauphine – PSLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1505442020-11-30T03:45:15Z2020-11-30T03:45:15ZWe modelled how a COVID vaccine roll-out would work. Here’s what we found<figure><img src="https://images.theconversation.com/files/371408/original/file-20201125-25-i4au1s.jpg?ixlib=rb-1.1.0&rect=0%2C10%2C1000%2C652&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/truck-on-fast-express-road-motion-320983172">Shutterstock</a></span></figcaption></figure><p>How well we distribute and administer a COVID-19 vaccine will have massive health, social and economic ramifications. So attention is turning to vaccine supply chains and logistics.</p>
<p>Designing how best to vaccinate billions of people worldwide is complex. This is particularly so for large countries, such as Australia, where <a href="https://theconversation.com/creating-a-covid-19-vaccine-is-only-the-first-step-itll-take-years-to-manufacture-and-distribute-144352">distributing vaccine</a> to rural and remote areas is needed.</p>
<p>Despite numerous past pandemics and epidemics, very few studies globally have tackled the problem of designing and building an efficient vaccine distribution network. <a href="https://link.springer.com/content/pdf/10.1007/s10729-012-9199-6.pdf">Existing</a> <a href="https://www.sciencedirect.com/science/article/pii/S1366554520306189">studies</a> have also not fully considered all factors affecting vaccine distribution.</p>
<p>So our team designed a mathematical model to test different scenarios for COVID-19 vaccine distribution, which we have submitted for publication.</p>
<h2>What we took into account</h2>
<p>Our model looked at different ways to distribute COVID vaccine to 6.9 million Victorians, based on the number of residents <a href="https://www.abs.gov.au/statistics/people/population/population-projections-australia/latest-release">predicted in 2021</a>.</p>
<p>We modelled this using distribution via the <a href="https://discover.data.vic.gov.au/dataset/hospital-locations-spatial">state’s 325 medical centres</a>, which can be everything from big city hospitals to small medical centres in regional areas.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/371419/original/file-20201126-17-p9fy0a.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of medical centres in Victoria" src="https://images.theconversation.com/files/371419/original/file-20201126-17-p9fy0a.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/371419/original/file-20201126-17-p9fy0a.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=441&fit=crop&dpr=1 600w, https://images.theconversation.com/files/371419/original/file-20201126-17-p9fy0a.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=441&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/371419/original/file-20201126-17-p9fy0a.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=441&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/371419/original/file-20201126-17-p9fy0a.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=554&fit=crop&dpr=1 754w, https://images.theconversation.com/files/371419/original/file-20201126-17-p9fy0a.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=554&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/371419/original/file-20201126-17-p9fy0a.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=554&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This map shows the location and capacity of the 325 medical centres in Victoria, using data from Victoria’s health department.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We assumed most vaccine distribution would be by road and enough <a href="https://theconversation.com/keeping-coronavirus-vaccines-at-subzero-temperatures-during-distribution-will-be-hard-but-likely-key-to-ending-pandemic-146071">refrigerated vehicles</a> would be available.</p>
<p>We also factored into our model that certain sections of the community are at increased risk of exposure (for instance, city dwellers) and others are more susceptible to infection (for instance, aged-care residents and health-care workers). These people are not uniformly distributed around the state, affecting vaccine distribution logistics.</p>
<p>We then tested different scenarios to see how long vaccination would take.</p>
<p>Our research shows we need three key factors for success.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/scientific-modelling-is-steering-our-response-to-coronavirus-but-what-is-scientific-modelling-135938">Scientific modelling is steering our response to coronavirus. But what is scientific modelling?</a>
</strong>
</em>
</p>
<hr>
<h2>1. Medical centres need to be big enough</h2>
<p>We calculated that if the capacity of the 325 medical centres is large enough, and if enough vaccine is available, the entire population of Victoria can be vaccinated within 60 days.</p>
<p>By capacity we mean the maximum number of vaccine doses each medical centre can administer. And this capacity depends on a range of factors including centres’ physical size, and having enough staff to administer vaccines.</p>
<p>This time frame or “target horizon” is the total number of days to vaccinate the population of Victoria. Although we have calculated this is possible within 60 days, the state or federal government will actually set this target.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/creating-a-covid-19-vaccine-is-only-the-first-step-itll-take-years-to-manufacture-and-distribute-144352">Creating a COVID-19 vaccine is only the first step. It'll take years to manufacture and distribute</a>
</strong>
</em>
</p>
<hr>
<p>To vaccinate all Victorians in 60 days, we calculated we would need a minimum of roughly 9,500 vaccine packs with 12 vaccines per pack, every day. This assumes one shot per person and adequate vaccines are available. A limited supply or a disruption to supplies might increase the administration period beyond 60 days.</p>
<p>If medical centres run at reduced capacity or existing capacity is not enough, this also increases the time taken to vaccinate. Conversely, if the aim is to vaccinate Victorians in under 60 days, our model suggests we need to boost our capacity to vaccinate.</p>
<p>This could be by using mobile vaccination units or hiring extra staff.</p>
<h2>2. Vaccines need to be shipped between medical centres</h2>
<p>We also show the importance of transporting vaccines between medical centres, known as transhipment. This allows medical centres short on vaccine to obtain doses from the nearest medical centres with extra supply.</p>
<p>Transhipment is also crucial when it comes to vaccinating the most vulnerable people. That’s because we can transfer vaccines from medical centres serving less-vulnerable populations to those with more residents in higher priority groups. Transhipment also allows us to transfer vaccines from areas with less exposure to areas of higher exposure. And it allows vaccines to reach remote areas.</p>
<p>However, transhipment places extra burden on road transport networks.</p>
<h2>3. Vaccine packs need to be the right size</h2>
<p>We also show it is important to get the vaccine pack size right. This seemingly minor detail had a significant effect on the overall period of vaccine administration.</p>
<p>We considered pack sizes that contain 5, 12, 20, 30 and 50 vaccines. Larger pack size significantly increases the need for transhipment between medical centres. That’s because larger packs would need to be broken up into smaller portions, then distributed to multiple medical centres.</p>
<p>We suggest governmental agencies carefully evaluate vaccine pack size when contracting and negotiating with vaccine manufacturers.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/keeping-coronavirus-vaccines-at-subzero-temperatures-during-distribution-will-be-hard-but-likely-key-to-ending-pandemic-146071">Keeping coronavirus vaccines at subzero temperatures during distribution will be hard, but likely key to ending pandemic</a>
</strong>
</em>
</p>
<hr>
<h2>This is relevant to all Australia</h2>
<p>While we used Victoria as a case study, we can apply our model to other states and territories. </p>
<p>In particular, the importance of pack size, transhipment between medical centres, and considering extra capacity to vaccinate in a shorter amount of time will apply in every context. </p>
<p>Certainly, the results for other states and territories will depend on their number of available medical centres, population size and population distribution.</p>
<p>Our model helps decision makers strike a balance between the cost of building extra capacity to try to achieve population vaccination in a given time scale or accepting a less costly approach that takes more time.</p><img src="https://counter.theconversation.com/content/150544/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>We’re on the road again. Getting enough COVID-19 vaccine to where it’s needed in a given time frame is the next logistical hurdle.Olga Kokshagina, Researcher - Innovation & Entrepreneurship, RMIT UniversityBabak Abbasi, Professor, Head of Department, Information Systems, RMIT UniversityMasih Fadaki, Lecturer, Supply Chain Management, RMIT UniversityNaima Saeed, Associate Professor of Supply Chain Management, University of AgderPrem Chhetri, Professor, Director, Global Supply Chain and Logistics Research Priority Area, RMIT UniversityLicensed as Creative Commons – attribution, no derivatives.