Clinical trials demonstrate how effective vaccines are individually, but the real world shows how effective they are at a population level.
AP Photo/Mark Lennihan, Pool
Using a robust statistical model, researchers estimate that coronavirus vaccines had prevented 140,000 deaths by May 9, 2021.
A vaccination done at a pop-up site in Johannesburg. Not enough South Africans are coming forward to get their shots.
Photo by Sharon Seretlo/Gallo Images via Getty Images
Epidemics do not require the total eradication of the disease to end.
People getting vaccinated may still have questions about COVID-19 vaccines, like why it takes two doses — and then two weeks — to take full effect.
THE CANADIAN PRESS/Ryan Remiorz
A medical student answers questions he gets asked at a COVID-19 vaccine clinic: Efficacy versus real-world effectiveness, immune response and how the mRNA vaccines compare to vaccines already in wide use.
Vaccine efficacy statistics are often based on the results of randomized controlled trials.
Vaccine efficacy is usually expressed as a percentage, but what is it actually measuring? Statisticians explain what the numbers mean, and what they say about how well a vaccine can protect us.
AstraZeneca, Pfizer and Moderna appear equivalent in reducing your chance of serious illness from COVID-19.
China has administered more than one billion doses of its homegrown COVID-19 vaccines, the majority of which were developed by local companies Sinovac and Sinopharm. So what do we know about them?
Even if we came up with a definition of what makes the “best” vaccine, we don’t have the luxury of choice, when vaccines are in short supply.
Houses in the city of Victoria, the capital of Seychelles.
What does the Seychelles experience tell us about variants, vaccine efficacy and herd immunity?
Make that second appointment and get your final dose for full protection.
MediaNews Group/Reading Eagle via Getty Images
An immunologist explains that you get some protection from the first dose of the mRNA vaccines but you need two to build up strong immunity, particularly to newer coronavirus variants.
A COVID-19 vaccine is administered at a clinic at Olympic Stadium in Montréal on March 1, 2021, marking the beginning of mass vaccination in the Province of Québec based on age.
THE CANADIAN PRESS/Paul Chiasson
With four COVID-19 vaccines approved for use in Canada, it’s time to answer FAQs about efficacy, immunity, eradication and variants.
Israel has the highest rate of COVID-19 vaccine coverage worldwide, and so has been one of the first countries to report on vaccine effectiveness.
Real-world studies of vaccines aren’t directly comparable with clinical trials, but their results are still good news.
Tamara Dus, director of University Health Network Safety Services, administers a Pfizer-BioNTech COVID-19 vaccine in Toronto.
THE CANADIAN PRESS/Frank Gunn
The arrival of COVID-19 vaccines has raised hope for an end to the pandemic. Hopefully that’s true, but there are variables. Here are some factors that could affect the success of the vaccine rollout.
New trial data appears to support pushing back the second dose to 12 weeks.
The vaccine is still very likely to be protective in over-65s, even if efficacy in this age group is unknown.
All predictions, whether scientific or political, include uncertainty.
CasarsaGuru/E+ via Getty Images
Whether you are predicting the outcome of an election or studying how effective a new drug is, there will always be some uncertainty. A margin of error is how statisticians measure that uncertainty.
Data coming through from phase 3 trials are encouraging. But participants don’t represent the whole community — so we can’t be sure these vaccines will work as well in everyone.
A woman walks by graffiti reading ‘No vaccine, No tracking, No COVID’, in Montréal on Aug. 16, 2020.
THE CANADIAN PRESS/Graham Hughes
COVID-19 vaccines are at risk of being undermined by vaccine hesitancy. Pharma must take steps to ensure transparency in data monitoring committees and trial data to build public trust in vaccines.
We will struggle to find a vaccine that works perfectly for people who need it most, despite what the headlines say is coming in 2021.
Two more COVID-19 vaccines may now be on the cards for Australia, should they pass clinical trials. But, as with earlier vaccine deals, there are no guarantees.
How much longer must society wait for a vaccine?
ANDRZEJ WOJCICKI/Getty Images
Several vaccines are in Phase 3 trials. So when will we know whether any of these will protect against COVID-19?