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Reports of very rare blood clots – AstraZeneca Vaccine

This page was last updated on 25 June 2021 at 12.00hrs.

The Medicines and Healthcare products Regulatory Agency (MHRA) and the Joint Committee for Vaccination and Immunisation (JCVI) have both reported an extremely rare adverse event of thrombosis (blood clots) and thrombocytopenia (low platelet count) following vaccination with the first dose of AstraZeneca ChAdOx1 nCoV-19 vaccine (AZD1222)

The MHRA is carrying out a detailed review of reports of a very rare blood clotting problem affecting a small number of people who have had the AstraZeneca vaccine.

The problem can also happen in people who have not been vaccinated and it's not yet clear why it affects some people.

The COVID-19 vaccine can help stop you getting seriously ill or dying from coronavirus. For people aged 30 or over and those with other health conditions, the benefits of being vaccinated outweigh any risk of clotting problems.

For people under 40 without other health conditions, it's currently advised that it's preferable to have another COVID-19 vaccine instead of the AstraZeneca vaccine.

Call your GP immediately if you get any of these symptoms starting from around 4 days to 4 weeks after being vaccinated (in an emergency please call 999):

  • a severe headache that is not relieved with painkillers or is getting worse
  • a headache that feels worse when you lie down or bend over
  • a headache that's unusual for you and occurs with blurred vision, feeling or being sick, problems speaking, weakness, drowsiness or seizures (fits)
  • a rash that looks like small bruises or bleeding under the skin
  • shortness of breath, chest pain, leg swelling or persistent abdominal (tummy) pain

Find out more about COVID-19 vaccination and blood clotting on GOV.UK

Anyone who did not have these side effects should come forward for their second dose when invited.

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