COVID-19 Vaccine AstraZeneca: benefits still outweigh the risks despite possible link to rare blood clots with low blood platelets

The European PRAC has concluded its preliminary review of a signal of blood clots in people vaccinated with COVID-19 Vaccine AstraZeneca and confirmed its benefits in combating the still widespread threat of COVID-19 continue to outweigh the risk of side effects.

SPS commentary:

The PRAC confirmed that there is no increase in overall risk of blood clots, but that the vaccine may be associated with very rare cases of blood clots associated with thrombocytopenia. The Committee looked in detail at records of disseminated intravascular coagulation (DIC) and cerebral venous sinus thrombosis (CVST) reported as of 16th March, at which time around 20 million people in the UK and EEA had received the vaccine. It is difficult to estimate a background rate of these events in people who have not received the vaccine, as they are rare and Covid-19 itself often causes blood clotting disorders, but based on pre-Covid figures, there was an imbalance in people under 50 years (DIC: 5 cases reported; <1 expected; CVST: 12 cases; 1.35 expected). 

The PRAC will undertake an additional review of these risks and close safety monitoring of reports of blood clots will continue. If symptoms suggestive of clotting problems occur, people should seek immediate medical attention. Steps are being undertaken to update the product information to include more information on these risks.


European Medicines Agency