A European Union regulator has recommended that the Johnson & Johnson COVID-19 vaccine should include a warning about unusual blood clots with low platelets. The European Medicines Agency (EMA) safety committee (PRAC) said the events should be listed as very rare side effects of the vaccine.
However, the committee noted that “based on the currently available evidence, specific risk factors have not been confirmed.” It also said that “the reported combination of blood clots and low blood platelets is very rare, and the overall benefits of COVID-19 Vaccine Janssen in preventing COVID-19 outweigh the risks of side effects.”
Johnson & Johnson had postponed its rollout of the vaccine in Europe after the Centers for Disease Control and Prevention and FDA flagged six instances of rare, severe blood clots occurring with low platelets. All six cases involved women under 60 and occurred within three weeks of inoculation, the agencies had said.
During an emergency meeting held by the CDC’s Advisory Committee on Immunization Practices (ACIP), Johnson & Johnson revealed a seventh woman had reported a blood clot, but it did not occur in the brain like the others and another case that involved a male during clinical trials but could not be linked to the shot at that time.
The clots, identified as cerebral venous sinus thrombosis (CVST), were concerning to authorities because they cannot be treated the same as other clots. The EU committee said that the eight cases reviewed “were very similar to the cases that occurred with the COVID-19 vaccine developed by AstraZeneca, Vaxzevria.”
The committee said a “plausible explanation” for the clots and low platelets “is an immune response, leading to a condition similar to one seen sometimes in patients treated with heparin called heparin induced thrombocytopenia, HIT.”
In a press conference held following the release of its recommendation, the committee said it would continue to review data and planned to ask Johnson & Johnson to conduct studies of their own.