A safety committee with Europe’s regulator concluded AstraZeneca's COVID-19 vaccine is safe and effective, with no ties to an overall increased risk of blood clots in vaccinated individuals. However, a definitive link to serious blood disorders could not be ruled out.
Top officials with the European Medicines Agency said the benefits of the vaccine against COVID-19 and its associated hospitalizations and deaths continue to exceed the risks of side effects.
"PRAC [the safety committee] noted the number of thromboembolic events reported after vaccination [469 reports] is lower than the expected in the general population and PRAC has concluded that there is no increase in the overall risk of blood clots with this vaccine," said Dr. Sabine Straus, chair of the safety committee.
Straus noted the vaccine is effective against COVID-19 disease, and likely reduces the risks of blood clotting events overall. However, insufficient evidence prevented the committee from concluding that serious adverse events were not vaccine-related.
As of Wednesday evening, the committee noted "very rare" case reports of serious blood disorders, including seven causes of clotting in multiple blood vessels within seven to 14 days post-vaccination, and 18 reports of clots in vessels draining blood from the brain. The serious case reports come amid a backdrop of nearly 20 million vaccinations across Europe.
The EMA said the safety committee will continue to run investigations to assess reports. The agency stressed awareness of the risks for both patients and providers, and advised including the risks in the vaccine's product information.
Emer Cooke, executive director of the EMA, stopped short of weighing in on some member states’ paused AstraZeneca vaccine campaigns. Rather, the regulator's "responsibility," Cooke noted, "is to come to a conclusion as to whether or not the benefits outweigh the risks of the vaccines so that countries can make an informed decision and increase trust in the vaccine."
Germany, France, Italy and Spain joined the growing list of mostly European countries — starting with Denmark last week — that temporarily halted the use of the AstraZeneca vaccine in recent days to investigate cases of blood clots that occurred after vaccination. Others include Thailand and Congo.
Many countries with paused vaccinations were hinging on a conclusion from regulators.
The Associated Press contributed to this report.