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Vials of AstraZeneca vaccine
J J Guillen/EPA-EFE

COVID vaccine weekly: AstraZeneca supplies and efficacy under the microscope again

Disputes over the Oxford/AstraZeneca vaccine have dominated the week, just as they have at various points over the past few months.

Europe’s leaders have so far largely resisted restricting exports of doses manufactured on the continent that are destined for other countries. But the EU is still concerned that the UK has an unfair advantage, as millions of vaccine doses have been exported from the EU to Britain with none being exported back in return.

Partly this appears to be down to differences in what each agreed with AstraZeneca. Britain’s contract is more forceful in making sure that supplies are delivered on time, and so appears to be being prioritised. The UK and the EU have jointly stated that they want to “create a win-win situation and expand vaccine supply for all”, but it’s not yet clear what the solution is.

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India has also restricted exports of doses it has manufactured as it looks to stem a rapid rise in cases, which could mean a delay to 5 million doses of the Oxford/AstraZeneca vaccine being sent to Britain. Combined with events in Europe, this creates the prospect of uneven or “lumpy” supply that could fail to meet demand and then run out.

This, though, can be compensated for, write Amir Sharif, Liz Breen and Sankar Sivarajah of the University of Bradford. A way forward would be to focus again on prioritising specific people and reducing the overall speed of vaccination, to allow fluctuations in supply to be better absorbed. Intergovernmental arguments should not then rear their head.

It hasn’t been plain sailing for the vaccine this week on the other side of the Atlantic either. Preliminary findings of the phase 3 trial being conducted in the US were announced early in the week, and they looked positive. Two doses of the vaccine, given four weeks apart, appeared to prevent symptomatic disease 79% of the time – which was slightly better than findings from previous trials.

Yet immediately, the data and safety monitoring board overseeing the trial called these results into question, saying that they were based on “outdated information”. AstraZeneca has since given an updated efficacy reading for the trial of 76%. The figures aren’t particularly different, but given there have been uncertainties about the vaccine’s efficacy before, this was an unwelcome distraction.

In reality, the trial’s results are actually very positive, writes Michael Head, senior research fellow at the University of Southampton. It found the vaccine was effective across all age groups, and 20% of the 32,000 people involved were over-65, which should allay concerns about it potentially being less effective in older people. The trial also reported no instances of blood clotting – welcome news after last week’s concerns that the vaccine might be associated with these.

On this front, the European Medicines Agency has so far found no evidence of a link and has said the vaccine is safe, but has also launched a further review into the clots that have been reported. Many countries that paused giving the Oxford/AstraZeneca vaccine last week have now resumed rolling it out, but some, such as Denmark, have prolonged the vaccine’s suspension.

Soeren Brostroem, director of Denmark's National Board of Health, with Tanja Erichsen of the Danish Medicines Agency
Soeren Brostroem, director of Denmark’s National Board of Health, outlines the country’s continued suspension of the vaccine. Mads Claus Rasmussen

Such suspensions, both then and now, are wrong, argue Julian Savulescu, Dominic Wilkinson, Jonathan Pugh and Margie Danchin from the University of Oxford. They can undermine confidence in vaccines – indeed, the Oxford vaccine has taken a real hit – and by delaying giving a vaccine against a deadly disease, may be a risk to public health far greater than blood clots. They’re also highly paternalistic – preventing people from making their own decisions about what risk they want to face: that of COVID-19 or of vaccination.

Nevertheless, these policies were common across Europe. This, says Stephen John, senior lecturer in philosophy of public health at the University of Cambridge, may be proof of a bias in our thinking: that we believe actively doing harm to be worse than passively allowing it, even if the size of the harm allowed is far greater.

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