Coronavirus: update on investigation of thromboembolic events with AstraZeneca’s COVID-19 vaccine

date: 16/03/2021

Several authorities responsible for national vaccination campaigns in other EU countries have temporarily suspended vaccination with AstraZeneca’s COVID-19 vaccine. This is a precaution taken in the light of their national situation while EMA investigates a number of events of blood clots in people who had received the vaccine, as previously reported.

Events involving blood clots, some with unusual features such as low platelet counts, have occurred in a very small number of people who received the vaccine. To date, six cases of thromboembolic events and other conditions related to blood clots have been reported in Belgium for AstraZeneca’s COVID-19 vaccine. These cases were reported recently, after concerns were raised in different EU countries, although they occurred before the recent media attention. Annually, many thousands of people develop blood clots in the EU for different reasons. The number of overall thromboembolic events in vaccinated people seems not to be higher than seen in the general population.

EMA is working closely with AstraZeneca, with experts in blood disorders, and with other health authorities including the British medicines agency MHRA, based on its experience with around eleven million administered doses of the vaccine.

EMA's investigation has been continued over the weekend, and rigorous analysis of all the data related to thromboembolic events will be carried out in the following days. EMA's safety committee (PRAC) will further review the information and has called an extraordinary meeting on Thursday 18 March 2021 to conclude on the information gathered and any further actions that may need to be taken.

The COVID-19 pandemic is a global crisis, with devastating health, social and economic impact, and continues to be a major burden on EU health systems. COVID-19 vaccines help to protect individuals from becoming ill, especially healthcare professionals and vulnerable populations, such as older people or those with chronic diseases. While the investigation is ongoing, the FAMHP and EMA currently believe that the benefits of the AstraZeneca vaccine in preventing COVID-19, with its associated risk of hospitalisation and death, outweigh the risks of adverse reactions.

The FAMHP and EMA will continue to communicate further as appropriate. It is important that people who suspect they may have an adverse reaction after vaccination report via The most common side effects with AstraZeneca’s COVID-19 vaccine are usually mild or moderate and improve within a few days after vaccination.

Accelerated review
The review of thromboembolic events with AstraZeneca’s COVID-19 vaccine is being carried out in the context of a safety signal, under an accelerated timetable. A safety signal is information on a new or incompletely documented adverse event that is potentially caused by a medicine and that warrants further investigation.

The review is being carried out by EMA's Pharmacovigilance Risk Assessment Committee (PRAC), the Committee responsible for the evaluation of safety issues for human medicines. Once the review is completed, PRAC will make any recommendations necessary to minimise risks and protect patients' health.

Last updated on 06/05/2021