Public demand for AstraZeneca vaccine falls after blood clot scares



A medical worker fills a syringe with AstraZeneca vaccine at Santa Caterina da Siena – Amendola secondary School in Salerno on March 13, 2021 in Salerno, Italy.

Francesco Pecoraro | Getty Images News | Getty Images

LONDON — Public preference for the coronavirus vaccine developed by AstraZeneca and the University of Oxford has fallen since reports emerged potentially linking it to some cases of unusual blood clotting events.

A study of almost 5,000 adults in April in the U.K. — where Covid vaccine take-up is high and the immunization program well-established — has found that the public’s preference for the AstraZeneca Covid vaccine has declined since March, and belief that it causes blood clots has increased.

The British academic study found 17% of the public now say they’d prefer to have the AstraZeneca vaccine, if they had a choice of any — down from 24% toward the end of March.

And 23% of people now believe the AstraZeneca vaccine causes blood clots — up from 13% in March. However, the public are still most likely to say this claim is false (39%) or that they don’t know whether it’s true (38%).

The study, carried out by the University of Bristol, King’s College London and the NIHR Health Protection Unit in Emergency Preparedness and Response between April 1-16, found a “big difference” in beliefs before and after the MHRA (the U.K.’s drug regulator) announced there was a possible link between the vaccine and extremely rare blood clots on April 7.

The study found that 17% of those interviewed in the first week of that month thought this claim was true, compared with 31% interviewed after.

Why the fall?

Since its first clinical data was released showing the vaccine had an average efficacy rate of 70% (subsequent trials in the U.S. found an efficacy rate of 79% and other trials have shown the efficacy rate to rise with a wider gap between the first and second doses) the fortunes of the AstraZeneca vaccine have been mixed, to say the least.

Read more: Data, doubts and disputes: A timeline of AstraZeneca’s Covid vaccine problems

One of the more recent hurdles faced by the AstraZeneca vaccine were a small number of reports of unusual blood clotting events, some of which were fatal, that emerged in post-vaccinated people in Europe in February, leading several countries to suspend use of the vaccine.

The U.K. and EU drug regulators (the U.K.’s Medicines and Healthcare Products Regulatory Agency and the European Medicines Agency) investigated the reports and said while there was a possible link between the vaccine and a small number of blood clotting incidents, the benefits of the vaccine greatly outweighed the risks.

The British-Swedish vaccine maker, U.K. government and experts largely defended the vaccine, saying that it had protected millions of people by reducing the number of Covid cases, hospitalizations and deaths.

In addition, experts sought to put the risk into context, saying that the number of rare blood clotting cases with low platelets reported equated to around one case per 250,000 people vaccinated and one death in a million.

The U.K. is fortunate in that it has traditionally had a high level of public support for vaccinations. The survey on vaccine preference found that despite the growing belief that the AstraZeneca vaccine is linked to blood clots, it has not dented overall levels of confidence in vaccines in general with 81% now saying vaccines are safe, compared with 73% who said the same toward the end of 2020.
There has been a similar change in views of how well vaccines work: 86% say they are effective, an increase from 79% in Nov-Dec 2020.

Surveys have shown the public perception of the AstraZeneca vaccine has deteriorated in mainland Europe, however, and anecdotal evidence that people in the EU have been shunning the AstraZeneca vaccine (reportedly nicknamed the “Aldi” vaccine, after the low-cost grocery chain, because of its cheaper production cost and image) in favor of the coronavirus vaccine from Pfizer-BioNTech that is also predominant in the EU’s vaccination rollout.

Read more: ‘The damage is done’: Europe’s caution over AstraZeneca vaccine could have far-reaching consequences

Moderna‘s shot and Johnson & Johnson‘s shot have also been authorized for use in the EU and U.K. but have been distributed to a lesser extent, EU vaccination data shows.

Vaccine hesitancy can work both ways, it would seem. One British doctor was reported in the Evening Standard newspaper in January saying that some of his patients had turned down the chance to have the Pfizer vaccine, saying they would “wait for the English one.”


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