US regulator says 'no causal link' between Johnson & Johnson vaccine and blood clots

The statement from the US Food and Drug Administration comes amid an ongoing study of the vaccine's safety by European regulators

The Johnson & Johnson Covid-19 vaccine is seen at a pop up vaccination site inside the Albanian Islamic Cultural Center in the Staten Island borough of New York. AP Photo

Top US health authorities said on Friday that they have not yet found a "causal" link between Johnson & Johnson's Covid-19 shot and blood clots, as the EU drug regulator probed possible instances among those who have received the vaccine.

"At this time, we have not found a causal relationship with vaccination and we are continuing our investigation and assessment of these cases," said a statement from the US Food and Drug Administration.

The regulatory agency said it was aware of "a few individuals" in the United States who had suffered clots and low levels of platelets in the blood after receiving Johnson & Johnson's vaccine.

"Both conditions can have many different causes," the FDA said. "We will keep the public updated as we learn more."

EU vaccine safety probe 

As US regulators continue monitoring the safety of the Johnson & Johnson shot, the EU has been more cautious, potentially adding more delays to vaccine rollouts across the continent.

Four cases, one fatal, of rare clots with low blood platelets were reported among those vaccinated with the shot, the European Medicines Agency (EMA) said in a statement.

The numbers of clot cases in people who took the shot have been small so far compared to the total number of people getting the vaccine worldwide, Peter Arlett, EMA’s head of analytics, said on April 7.

At that point, Mr Arlett said three clotting cases had been found, while some 4.5 million people had gotten the shot.

“I think it would be fair to say there is intensive monitoring of this issue across the vaccines,” Mr Arlett said.

The report from the EMA is the first to mention a probe of blood clots associated with the Johnson & Johnson vaccine.

The FDA said it was aware of the EMA's statement and provided the agency with the data that formed the basis of its report.

The EMA's statement follows an investigation of blood clots in the brain reported by some people given the AstraZeneca vaccine, which has prompted some European countries to change their vaccine recommendations.

In its report on Friday, EMA's safety committee said unusual blood clots linked with low blood platelets should be listed as very rare side effects of the AstraZeneca vaccine.

It has also started to investigate reports of capillary leak syndrome – which causes blood vessel swelling and a drop in blood pressure – in five people who received the AstraZeneca vaccine. The safety panel said it was not clear whether these were linked with the vaccine. AstraZeneca did not immediately respond to a request for comment.

Ian Douglas, a professor of pharmacoepidemiology at London School of Hygiene & Tropical Medicine, said the reports were part of a normal process in which the EMA's safety committee reviews important safety signals as they arise.