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What information is available on clotting risk after AstraZeneca vaccine?

On 18 March MHRA issued a statement that cases of blood clots with low platelet counts had been reported in the UK after COVID-19 Vaccine AstraZeneca. Cases were of cerebral venous sinus thrombosis (CVST) and other thrombosis events with low platelets. MHRA advised that for the vast majority of adults the benefits of vaccination continue to outweigh any risks and individuals should continue to be vaccinated when invited. Weekly updates of reported cases and deaths are included in the MHRA weekly report on COVID-19 vaccine Adverse Drug Reactions. 

On 7 April the Joint Committee on Vaccination and Immunisation (JCVI) issued a statement. On May 7 the JCVI issued a further statement advising  that that in addition to those age under 30,  for unvaccinated people aged 18 - 39 years without a long term health condition that puts them at greater risk from COVID-19 it 'is preferable to have a different COVID-19 vaccine instead of the AstraZeneca vaccine where it would not cause significant delay. PHW provide public information materials on the clotting risk. 

COVID-19 infection itself causes blood clots, and about 1 in 5 people admitted to hospital with COVID-19 infection experience serious blood clots as a complication. Being vaccinated with two doses of AstraZeneca COVID-19 vaccine prevents over 90% of serious complications and deaths from COVID-19.  

All individuals being offered an AstraZeneca COVID-19 vaccine should be provided with the relevant information including on benefits and risks, and have the opportunity to discuss this with a registered healthcare professional if they wish. 

The following resources are regularly updated: 

PHE  Information for healthcare professionals on blood clotting following COVID-19 vaccination 

MHRA weekly report on COVID-19 vaccine Adverse Drug Reactions