The European Medicine Agency (EMA) said that blood clots should be listed as a “very rare” side effect of the vaccine from US-based Johnson & Johnson (J&J), but assured that its benefits still outweigh the risks.
A “possible link” between the jab and the clots has been found, following eight such cases in the United States, one of which was fatal, the drug watchdog of the European Union (EU) said in a statement.
Concerns over the vaccine by US pharmaceutical giant Johnson & Johnson and the jab by rival UK-based drugmaker AstraZeneca have dampened hopes that vaccines could offer a swift end to the pandemic.
“EMA finds possible links to very rare cases of unusual blood clots with low blood platelets,” the agency said in a statement, adding that it “confirms the overall benefit-risk remains positive.”
The regulator said its safety committee “concluded that a warning about unusual blood clots with low blood platelets should be added to the product information” for the J&J shot. Its experts also “concluded that these events should be listed as very rare side effects of the vaccine.”
“The cases reviewed were very similar to the cases that occurred with the COVID-19 vaccine developed by AstraZeneca, Vaxzevria,” the EMA statement said.
The eight cases in the US, out of some seven million people who had received the vaccine, all involved people under the age of 60, the majority of whom were women, it said. “Based on the currently available evidence, specific risk factors have not been confirmed,” the EMA said.
Johnson & Johnson last week delayed the rollout of its single-shot jab across Europe pending the result of the EMA probe. The drugmaker said earlier that it was “very confident” in its vaccine and hopeful for a quick resolution from regulators over its status.
The EU approved the Johnson & Johnson shot on March 11 and started taking delivery of the vaccine on April 19. But with concerns already mounting over clots linked to AstraZeneca, the EMA announced on April 9 that it was also probing cases connected to the J&J vaccine. Meanwhile, US regulators have suspended the Johnson & Johnson vaccine and are set to announce its decision soon.
Adenovirus vector technology
Both the Johnson & Johnson and AstraZeneca vaccines use the same adenovirus vector technology. They use a common-cold causing adenovirus, modified so it cannot replicate, as a “vector” to shuttle genetic instructions into human cells, telling them to create a protein of the coronavirus, and training them to be ready for live COVID-19.
AstraZeneca opted for a chimpanzee adenovirus, J&J for a human adenovirus. Other COVID-19 adenovirus vector vaccines include Russia’s Sputnik V and China’s CanSino.
However, many European countries have continued to restrict the use of AstraZeneca, despite the EMA declaring it safe and saying blood clots are only a “very rare” side effect.