The United States should resume use of the Johnson & Johnson COVID-19 vaccine for all adults, an independent advisory committee to the Centers for Disease Control and Prevention (CDC) said today. There is a small risk of a rare type of blood clot in women under 50, and health officials should warn patients of that risk, the committee stressed during its deliberations.

Federal officials at the CDC and Food and Drug Administration (FDA) could lift the pause on the shot based on that recommendation soon — within hours or days. The FDA will likely add a warning label to the vaccine about the blood clots.

Use of the Johnson & Johnson vaccine has been paused in the US since April 13 as officials gathered more information about reports of unusual blood clots in a few people who received the shots. The patients had a type of blood clot that appears in the brain, called cerebral venous sinus thrombosis, along with low levels of blood platelets.

CDC’s Advisory Committee on Immunization Practices (ACIP) said that the pause should be lifted after discussing the ways that the benefits of the Johnson & Johnson shot outweigh the risk of the blood clot, which is extremely rare. This vaccine can protect people from COVID-19, and is also a key tool to protect vulnerable groups like people experiencing homelessness from the disease.

There have not been similar reports in people who received the Pfizer / BioNTech or Moderna vaccines. Around 200 million doses of those vaccines have been administered in the US.

As of today, around 8 million people in the US have received the Johnson & Johnson shot and there are 15 confirmed cases of the clots, all in women. Other potential cases are under investigation. Two of the women with confirmed cases are over 50 years old, and 13 are between 18 and 49 years old. Three of the women died, seven are hospitalized, and five are recovering at home.

Based on the available data, the risk of the clotting condition in women under 50 is seven cases per 1 million doses of the Johnson & Johnson vaccine, the ACIP’s COVID-19 Vaccines Safety Technical Work Group found. The risk for women above 50 and men is less than one case per 1 million doses.

The risk of this unusual condition has to be balanced against the benefits of the Johnson & Johnson vaccine, said Grace Lee, associate chief medical officer for practice innovation at Lucile Packard Children’s Hospital in California and chair of the work group. The shots can prevent death, hospitalization, and clots associated with COVID-19. Johnson & Johnson calculated that for every 1 million doses of its vaccine given, 2,000 COVID-19-related deaths and 6,000 COVID-19-related hospitalizations could be prevented.

Part of the reason for the Johnson & Johnson pause was to give doctors and health care providers information about this clotting condition. Blood clots are usually treated with the blood thinner heparin, but in these patients, that type of medication could make the condition worse.

Increased awareness of the condition generated during the pause and investigation should help keep people safer, said Michael Streiff, the medical director of the Johns Hopkins Hospital Special Coagulation Laboratory, during a presentation at today’s ACIP meeting. Doctors know to look out for signs of these rare clots, and people who got the Johnson & Johnson vaccine will now know to look out for symptoms like a severe headache. Some of the people with the clots took a few days before they went to the doctor, and by that time, they were very sick, he said. “I think that education of the public and physicians will improve outcomes.”

The ACIP met last week just after the pause to discuss the initial reports, but said then that it did not have enough information to make a recommendation — effectively extending the pause. The CDC spent the interim collecting more information about the clots and their relationship to the Johnson & Johnson vaccine. “We would have done this work regardless of whether there was a pause or not,” Tom Shimabukuro, a member of the CDC’s COVID-19 Vaccine Task Force, said during the committee meeting. “The pause did really focus our efforts on getting to the bottom of this quickly.”

The CDC will continue to monitor cases of the clotting condition using the vaccine safety surveillance programs, which let patients and doctors report potential health problems after vaccination.