J.&J. will resume its Europe vaccine rollout after the E.U.’s regulator says the shot should carry a label.

BRUSSELS — Johnson & Johnson said Tuesday that it would resume its coronavirus vaccine rollout in Europe after the European Union’s drug regulators said a warning should be added to the product indicating a possible link to rare blood clots, but that the shot’s benefits outweigh the risks.

“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,” the European Medicines Agency said in a statement, referring to the division of Johnson & Johnson that develops vaccines, Janssen. The rare clots were “very similar,” the agency added, to those associated with the AstraZeneca vaccine, for which the agency made a similar recommendation.

Johnson & Johnson decided to delay its rollout in the bloc’s 27 member states last week, after U.S. regulators called for a pause on the vaccine following concerns about the potential serious side effect.

The EMA’s recommendation is not binding, but it is the first indication of what might happen next with the European rollout of the much-anticipated, single-shot vaccine that’s already been given to nearly eight million people in the United States. The agency said that regulators in individual E.U. member states should decide how to proceed taking into account their particular case load and vaccine availability.

The agency said it had come out with its recommendations ahead of any from U.S. regulators because it had built some confidence in how to respond in having spent much time reviewing similar cases that arose with the AstraZeneca vaccine.

In its statement, the agency stressed the importance of treating the potential side effect and issued guidelines to health care professionals on the lookout for the rare clotting disorder. Providers and vaccine recipients “should be aware of the possibility of very rare cases of blood clots combined with low levels of blood platelets occurring within three weeks of vaccination,” it said.

The agency, using already available data, said one possible explanation was that the blood disorder was an immune response.

The temporary suspension of the Johnson & Johnson rollout in the European Union compounded the bloc’s woes with the AstraZeneca vaccine. Vaccination efforts have fallen behind in Europe partly because the AstraZeneca was unable to deliver the number of doses expected in the first quarter of the year. The AstraZeneca vaccine was then suspended due to very similar blood-clotting concerns as those that regulators are now investigating for Johnson & Johnson’s product.

Even though the E.U. regulator eventually found that the benefits of the AstraZeneca vaccine outweighed risks, and that E.U. members should use it, the damage had been done. Many Europeans have been refusing to take the vaccine, and several E.U. countries have limited its use to older people, as most of those affected by the rare clots were younger than 60. The EMA declined to name at-risk groups of the population regarding both the AstraZeneca and Johnson & Johnson vaccines, even though most cases reported were among younger women. The agency said it didn’t have sufficient information to draw definitive conclusions.

The E.U. last week announced it was boosting its supply of the Pfizer-BioNTech vaccine, and was negotiating a new deal for future booster shots with the company for 2022 and 2023, signaling it was going to prioritize vaccines, like Pfizer’s and Moderna’s, that use the mRNA technology.

But the Johnson & Johnson vaccine has been an important component of vaccination plans from the United States to South Africa.

U.S. health officials called for a pause in the vaccine’s use on April 13 to examine a rare blood-clotting disorder that emerged in a small number of recipients. Johnson & Johnson suspended its E.U. rollout immediately afterward. E.U. countries had just begun receiving their first shipments of the vaccine, and all but Poland followed the company’s guidance and have not began administering it.

Six cases of the rare blood clotting that emerged in the U.S. were all women between the ages of 18 and 48, and developed the illness within one to three weeks of vaccination. One woman in Virginia died, and a second woman in Nebraska has been hospitalized in critical condition.

At a meeting of expert advisers to the Centers for Disease Control and Prevention on Wednesday, a representative from Johnson & Johnson presented information on two new cases, bringing the total to eight. The EMA said in their announcement that they reviewed all eight cases.

On Monday, the C.D.C. said that while federal health officials were investigating “a handful” of new, unconfirmed reports that had emerged since the pause nationwide, “no additional cases of the rare form of blood clots post-vaccination with the Johnson & Johnson vaccine have been confirmed.”

Dr. Anthony S. Fauci, the United States’ leading infectious disease expert, said previously that he anticipated a decision about whether to resume administering the Johnson & Johnson vaccine this Friday, when the expert panel that is advising the agency is scheduled to meet again.

On Tuesday, the White House press secretary Jen Psaki said that a total of 28 million doses were shipping this week to states, jurisdictions and federal programs, as the U.S. vaccination campaign continued with the other two authorized vaccines from Pfizer-BioNTech and Moderna.