European regulator says J&J coronavirus vaccine needs rare blood clot warning but that benefits outweigh risks

The decision by the European Medicines Agency was based on the same U.S. data that led American regulators last week to pause the use of the vaccine inside the United States.

Johnson & Johnson said after Tuesday's announcement that it would resume distribution in Europe. But the U.S. hold remains in place as American authorities make an independent evaluation. New guidance is expected as early as Friday, and top officials, including Anthony Fauci, say they expect the vaccine will also be given a green light.

The European regulators said Tuesday that unusual blood clots with low blood platelets should be listed on the packaging of the vaccine as "very rare side effects," but they took no further action. The regulators assessed that, overall, the vaccine is safe and effective.

"The benefits of the vaccine continue to outweigh these risks, and we now have detailed information in the labeling that alerts to these risks," said Emer Cooke, the head of the European Medicines Agency. "We're confident that it can be rolled out appropriately."

Six cases of unusual blood clots with possible ties to the vaccine had been reported in the United States last week. The European regulators said they had evaluated eight U.S. cases, without explaining the discrepancy.

Nearly 7 million shots of the Johnson & Johnson vaccine had been administered in the United States before the pause. Public health officials especially appreciated that the inoculation involves just a single dose, making it easier to give to vulnerable and underserved populations for whom a follow-up appointment for a second shot could be difficult.

The vaccine has been slower to roll out in Europe, with only two E.U. countries - Poland and Luxembourg - using it since it became available last week. In response to the U.S. Food and Drug Administration's halt on April 13, Johnson & Johnson halted its European distributions, as well. There had been no formal European hold on the use of the vaccine, apart from the drugmaker's own pause in deliveries.

"We appreciate the rigorous review," said Johnson & Johnson's chief scientific officer, Paul Stoffels, in a statement after the European announcement. We "share the goal of raising awareness of the signs and symptoms of this very rare event to ensure the correct diagnosis and appropriate treatment."

The European regulators noted that the blood clots in the United States were similar to cases in Europe among people who had received the Oxford-AstraZeneca coronavirus vaccine, which also uses "viral vector" technology. The vaccines produced by Pfizer-BioNTech and Moderna are based on messenger RNA technology, instead, and are not suspected to cause any unusual clotting.

Many European countries have restricted the AstraZeneca vaccine to older age groups, after the majority of concerning clots were identified in younger people, most of them women - though regulators have said that may also reflect who was getting the vaccine.

The AstraZeneca vaccine is not currently authorized in the United States.

European regulators said it was not yet possible to determine whether there is more or less risk of blood clots associated with the Johnson & Johnson vaccine or with AstraZeneca's. At least 287 cases of unusual blood clots have been reported worldwide following the AstraZeneca vaccine, the E.U. regulators said, but that vaccine has been in use longer - since December in some countries.

Concerns about blood-clotting complications were first triggered in Europe when a nurse in Austria died soon after her AstraZeneca vaccination in mid-February. More cases followed, and though rare, their severity spurred action from medical regulators across the continent.

Teams of scientists in Germany and Norway have said the clots are caused by an antibody response triggered by the vaccine.

Scientists are still trying to work out what might cause one person to be more affected than another and whether young people or women might be disproportionately at risk.

For the AstraZeneca vaccine, the EMA estimates the risk of someone developing rare blood clots alongside a low platelet count to be about 1 in every 100,000 inoculations. Concerns largely center on cerebral venous sinus thrombosis, a clot that prevents blood from being drained from the brain and can cause hemorrhaging. The condition can be serious.

But doctors and regulators say early intervention and treatment can help, making it essential that medical workers and the public are informed of side effects to look for. Those include headaches or blurred vision occurring more than four days after vaccination.