Safety of the AstraZeneca Vaccine

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Recently, there have been reports of a very rare condition involving blood clots and unusual bleeding after vaccination. Although this condition remains extremely rare there appears to be a higher risk in people shortly after the first dose of the AstraZeneca (AZ) vaccine.

Around 4 people develop this condition for every million doses of AZ vaccine doses given. This is seen slightly more often in younger people and tends to occur between 4 days and 2 weeks following vaccination. This is being carefully reviewed but the risk factors for this condition are not yet clear.

This condition can also occur naturally, and clotting problems are a common complication of COVID-19 infection. An increased risk has not yet been seen after other COVID-19 vaccines but is being carefully monitored.


Following advice from the Joint Committee on Vaccination and Immunisation (JCVI), we will be offering people under 30 who have not yet had their first COVID-19 vaccination, a choice of vaccine other than AZ. If you choose to have an alternative vaccine you may have to wait to be protected. You may wish to go ahead with the AZ vaccination after you have considered all the risks and benefits for you.

This leaflet from Public Health England provides more information about the benefits and risks of the AZ COVID-19 vaccination.

If you have already had a first dose of AZ vaccine without suffering a blood clot as a side effect, you should have your second dose.


This includes people aged 18 to 29 years who are health and social care workers and unpaid carers.

The benefits of the AstraZeneca Covid-19 vaccine outweigh any risks for the vast majority of people and you should still book your COVID-19 vaccine when asked to do so.