Over the past weeks, several news on thromboembolic events potentially related to side effects of AstraZeneca’s vaccine for COVID-19 have been largely spread and disseminated. Events such as the death of a teacher in Spain as a consequence of brain haemorrhage days after receiving the first dose, or the report of young people in Norway with blood clots after having received AstraZeneca´s COVID-19 vaccine as well, have generated a global warning on the safety of this vaccine.
In this context, EMA’s safety committee and Pharmacovigilance Risk Assessment Committee (PRAC) – responsible for assessing the risk management of medicines for human use-, celebrated an extraordinary meeting last Thursday, the 18th of March. The aim was to discuss the relationship between these blood clots and AstraZeneca´s COVID-19 vaccine.
Association of AstraZeneca’s Vaccine and Thrombosis as Side Effects
According to the preliminary review of the respective EMA and PRAC committees, they concluded that there is not an association between the vaccine and the risk of thromboembolic events. Taking into account the clinical studies and the rollout of vaccination campaigns, a total of 469 thromboembolic events have been reported (191 in the European Economic Area). This number is inferior to the one expected in the general population.
In addition, the Pharmacovigilance Risk Assessment Committee (PRAC) concluded that there is no evidence of problems related to quality issues on the vaccine batches or manufacturing sites.
However, the PRAC highlighted that the AstraZeneca’s vaccine may be associated with very rare cases of thrombocytopenia with or without bleeding, including clots in the vessels draining blood from the brain (CVST) or blood clots in multiple blood vessels (Disseminated Intravascular Coagulation, DIC) (especially in young patients).
In total, among the 20 million people that have received AstraZeneca’s vaccine, only 7 cases of DIC and 18 cases of CVST have been reported.
Summary of side effects analysis of the AstraZeneca vaccine:
- The benefits of the vaccine continue to outweigh the risks of side effects.
- Cases in which side effects from the vaccine (thrombosis) have been reported are not linked, but merit analysis.
- The efficacy of the vaccine in preventing hospitalisations and deaths from COVID-19, outweighs the extremely low likelihood of developing DIC.
- The vaccine may be associated with very rare cases of blood clots.
- If patients experience side effects after receiving the AstraZeneca vaccine, they should contact their doctor.
Even though a causal link has not been demonstrated, the PRAC will perform further analysis, taking into account other COVID-19 vaccines, and recommends patients to seek immediate medical attention if they develop symptoms suggestive of clotting problems after vaccination.
Overall, it was concluded that the benefits of the vaccine outweigh the risk of side effects in the case of AstraZeneca vaccine for COVID-19.