A “possible link” exists between Johnson & Johnson’s Covid-19 vaccine and the rare side effect of blood clots combined with low platelet counts, the European Medicines Agency has concluded.
The European health agency said on Tuesday that unusual blood clots and low platelet counts should be added to the list of side effects from the J&J jab. It added, however, that the overall benefits of the single-shot vaccine outweigh the risks of these reactions.
The rollout of J&J’s vaccine in Europe was delayed last week after US health agencies recommended the shot be paused while they investigated the rare side effects seen in eight people who received it. The US Centers for Disease Control is expected to meet on Friday to decide its next steps.
Scientists have been racing to determine the cause of the reaction.
“One plausible explanation for the combination of blood clots and low blood platelets is an immune response, leading to a condition similar to one seen sometimes in patients treated with heparin called heparin induced thrombocytopenia, HIT,” the EMA said.
The eight cases seen in more than 7m people who received the J&J jab were “very similar” to cases that occurred in individuals who received the Oxford/AstraZeneca vaccine, the EMA said. It said individuals should seek urgent medical help if they experience symptoms including shortness of breath, chest pain and leg swelling three weeks after vaccination.
In an earnings call with analysts ahead of the EMA decision, Joaquin Duato, vice-chair of J&J’s executive committee, said: “We are looking forward to working with EMA to ensure appropriate awareness of this extremely rare event and guidance on diagnosis and treatment of this condition.”
He added that the company “stands ready” to resume the shipment of its jab to Europe, and is committed to delivering 200m vaccine doses to the EU, Norway and Iceland.
The EMA said that all cases of the rare side effects occurred in people under 60 years old, mainly women, and three weeks after vaccination. “By recognising the signs of blood clots and low blood platelets and treating them early, healthcare professionals can help those affected in their recovery and avoid complications,” it said.
Sales of Johnson & Johnson’s Covid-19 vaccine hit $100m in the first three months of the year. The drugmaker does not sell its single-shot Covid-19 vaccine for profit.
This week, the production of J&J’s vaccine at a plant in Baltimore was halted by the US Food and Drug Administration while it investigates the site run by Emergent BioSolutions that has been beset by manufacturing problems.
On Monday, the US House committee on oversight and reform launched a separate investigation into whether Emergent received contracts to manufacture vaccines “despite a long, documented history of inadequately trained staff and quality control issues”.
Duato said that the FDA’s assessment was expected to close this week and that J&J remained committed to ensuring that all substances used in its vaccine “meets our high quality standard”.