What's going on with the AstraZeneca vaccine? - Full Fact

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The risks, what the government has said, and what's happening for under-30s.
What's going on with the AstraZeneca vaccine?

8 April 2021

A number of announcements have recently been made about use of the Oxford-AstraZeneca Covid-19 vaccine, also known as Vaxzevria. This is due to a possible link between the first dose of the vaccine and a specific type of extremely rare blood clot, occurring alongside a low level of platelets (a component of the blood).

What's the risk?

In the period up until 31 March, 20.2 million doses of the AstraZeneca vaccine had been given in the UK, and the Medicines and Healthcare products Regulatory Agency (MHRA) received 79 reports of this specific type of clot. In 19 of these cases, the person died.

That's equivalent to an overall risk of roughly 1 in 250,000 of getting this type of clot after vaccination. This is a very broad estimate, so for some people the risk may be higher, and for some it may be lower.

To put this into context, we need to compare it with the likelihood of becoming very ill with Covid-19. But there are several factors to consider when it comes to how likely that is, mainly how likely someone is to catch the disease, and how likely they are to have a poor outcome as a result (which is affected mostly by age and health conditions).

The Winton Centre for Risk and Evidence Communication at Cambridge University has calculated the chances of getting this type of blood clot after the vaccine and compared that to the benefits of being vaccinated, which it chose to demonstrate as the number of admissions to intensive care avoided.

If the chances of catching Covid-19 are low, as they were in March 2021, then the immediate potential for harm from the vaccine for those aged 20-29 slightly outweighs the benefits. Vaccinating 100,000 people of that age will avoid about 0.8 ICU admissions due to Covid-19 in a 16 week period.

For the same age group, the…
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