European Thrombosis and Haemostasis Alliance Welcomes European Medicines Agency Decision on COVID-19 Vaccination and Blood Clots

18 March 2021 – The European Thrombosis and Haemostasis Alliance (ETHA) welcomes the European Medicines Agency’s (EMA) decision today following the recent reports of thrombotic events (blood clots) following COVID-19 vaccination and urges continued vaccination as these events are investigated by global regulatory authorities. EMA’s safety committee (PRAC) concludes that the benefits of the Covid-19 AstraZeneca still outweigh its risks despite possible link to rare blood clots associated with low levels of blood platelets.

Every year, there are approximately 10 million cases of venous thromboembolism worldwide (also known as VTE – a common type of blood clot)1. Spontaneous clots are so common that it is to be expected that some recently vaccinated people would also experience thrombotic events.

There is also significant evidence that many people experience blood clots as a result of a COVID-19 infection. In fact, in 2020 a broad group of organisations and individuals including the ETHA called upon the WHO to emphasise the importance of managing clotting in COVID-19 patients as a high priority (see statement).

Minimising the risk of death or disability from clots is a founding principle of the ETHA, and the Alliance reaffirms its commitment to that goal in response to this latest news about clotting events in Europe. Those who are concerned about the potential risk of clots are encouraged to follow simple guidelines on reducing their risk. And all are encouraged to familiarise themselves with the signs and symptoms of VTE.

This statement follows last week’s statement from the International Society on Thrombosis and Haemostasis (ISTH), here.

About the ETHA
The European Thrombosis and Haemostasis Alliance (ETHA) is made up of eminent clinicians and researchers from European national and international societies representing those working in the field of thrombotic and bleeding disorders. We have come together to give the European thrombosis and haemostasis community an allied voice and provide input to EU health and patient safety strategies; make recommendations on EU research programme funding and encourage sharing and adoption of best practices in the treatment and prevention of thrombotic and bleeding disorders across Member States.


For further information, please contact: or Sture Alne / ETHA secretariat on +32 488568225.

1. Jha AK, Larizgoitia I, Audera-Lopez C, Prasopa-Plaisier N, Waters H, Bates DW. The global burden of unsafe medical care: analytic modeling of observational studies. BMJ Qual Saf 2013; 22;809-15. Retrieved from: