Dr. Sabine Straus, chair of the European Medicines Agency's Pharmacovigilance Risk Assessment Committee, said Thursday that the committee had concluded there is no increase in the overall risk of blood clots with the AstraZeneca vaccine.
Screengrab by NPR/YouTube/European Medicines Agency
The European Medicines Agency said the AstraZeneca vaccine is safe, after several EU member states, including Germany, France, Italy, and Spain, suspended its use over reports of blood clots in a small number of people who received it.
"This vaccine is safe and effective in preventing COVID-19, and its benefits continue to be far greater than its risks," said Dr. Sabine Straus, chair of the EMA's Pharmacovigilance Risk Assessment Committee (PRAC).
The committee made the announcement after days of scientific assessments of the cases of blood clots – some fatal – in people who had received the vaccine.
"Moreover, because the vaccine is effective in preventing COVID-19 disease, which in itself is a cause of blood clots, it likely reduces the risk of thrombotic events overall," Straus continued.
The committee found no evidence of a quality or batch issue, and it delved into the data concerning blood clots.
It found that the number of thromboembolic events reported after vaccination is lower than expected in the general population, and concluded that there is no increase in the overall risk of blood clots with the AstraZeneca vaccine.
There are still some uncertainties, the committee noted, citing very rare case reports describing "specific, unusual events" of a combination of blood clots, low blood platelet levels, and bleeding. In a few cases, tiny clots developed in multiple blood vessels in the first 7-14 days after vaccination. And in a few other cases, clots developed in blood vessels, draining blood from the brain.
"The evidence we have is at the moment not sufficient to conclude with certainty whether these adverse events are indeed caused by the vaccine or not," Straus said.
PRAC will continue to gather information and studies on these conditions.
These adverse events are rare, the committee emphasized: out of almost 20 million people who received the vaccine in European countries, there were seven reported cases of disseminated intravascular coagulation and 18 reported cases of cerebral venous sinus thrombosis. Such cases were not identified in the large-scale clinical trials.
"The Committee was of the opinion that the vaccine's proven efficacy in preventing hospitalisation and death from COVID-19 outweighs the extremely small likelihood of developing [these rare conditions]," PRAC said in a statement. "However, in the light of its findings, patients should be aware of the remote possibility of such syndromes, and if symptoms suggestive of clotting problems occur patients should seek immediate medical attention and inform healthcare professionals of their recent vaccination."