The European Medicines Agency (EMA) has released further information and advice concerning the AstraZeneca vaccine and thrombosis and bleeding:

“EMA’s safety committee, Pharmacovigilance Risk Assessment Committee (PRAC), concluded its preliminary review of a signal of blood clots in people vaccinated with COVID-19 Vaccine AstraZeneca at its extraordinary meeting of 18 March 2021. The Committee confirmed that:

  • The benefits of the vaccine in combating the still widespread threat of COVID-19 (which itself results in clotting problems and may be fatal) continue to outweigh the risk of side effects;
  • The vaccine is not associated with an increase in the overall risk of blood clots (thromboembolic events) in those who receive it;
  • There is no evidence of a problem related to specific batches of the vaccine or to particular manufacturing sites;
  • However, the vaccine may be associated with very rare cases of blood clots associated with thrombocytopenia, i.e. low levels of blood platelets (elements in the blood that help it to clot) with or without bleeding, including rare cases of clots in the vessels draining blood from the brain (CVST).”

The EMA’s full statement can be viewed at

The full press briefing can be viewed at

Cerebral venous sinus thrombosis (CVST) is very rare (around 5 cases per million people per year) and a very uncommon cause of stroke. It presents with severe headache, blurred vision and if it progresses, loss of consciousness.  Women are affected more than men, usually because of oestrogen use and pregnancy, which are also mild risk factors for thrombosis.

Early recognition of symptoms is important, as is seeking medical attention.

Saturday, 20 March 2021