Expert advisers to the Centers for Disease Control and Prevention will meet on Thursday to discuss what federal health officials see as a concerning increase in the rates of a rare but serious blood clotting disorder linked to Johnson & Johnson’s coronavirus vaccine.
The Advisory Committee on Immunization Practices will see new data at the meeting that shows elevated risks of the condition in men and women, according to one federal official, setting the stage for the experts to possibly recommend new restrictions on the use of the vaccine.
The F.D.A. on Tuesday said that although problems arose in men and women, the highest rate was in about 1 in 100,000 in women aged 30-49.
Among the women who were diagnosed with the syndrome, which can impair clotting and cause internal bleeding, about one in seven of them died, the F.D.A. said. The federal official who described the planning for Thursday’s meeting said that updated figures showed roughly nine deaths from the disorder.
The panel on Thursday may advise that the vaccine only be given to people who cannot access a different brand or who want it despite the risk, or restrict it to certain groups.
The Washington Post first reported the plans for Thursday’s meeting and the new federal data.
Jake Sargent, a spokesman for Johnson & Johnson, said the company shares with regulators reports of side effects in people who have received the vaccine and “strongly support raising awareness of the signs and symptoms of this rare event.”
About 16 million people in the United States have received a single shot of the Johnson & Johnson vaccine as their primary immunization, compared to 73 million fully immunized with Moderna’s vaccine and 113 million with Pfizer’s. Among the people in the United States who have received a booster shot, just 1.5 percent have gotten the one from Johnson & Johnson.
The side effect, known as thrombosis with thrombocytopenia syndrome, can impair clotting and cause internal bleeding. An increased risk for the condition has been linked to the Johnson & Johnson vaccine and the shot from AstraZeneca, which is not authorized in the United States. It has not been linked to the vaccines from Moderna or Pfizer.
On Tuesday, the Food and Drug Administration announced that it added a warning to the vaccine’s fact sheets for patients and providers, saying the shot should not be given to anyone who has had a clotting problem after a first dose. The agency said that it “continues to find” that the benefits of the vaccine outweigh its risks.
As more cases of the clotting disorder were adjudicated by federal health officials in recent months, F.D.A. and C.D.C. officials grew increasingly alarmed by the numbers presented to them by the C.D.C.’s immunization safety office, which monitors reports in the Vaccine Adverse Event Reporting System, or VAERS, a decades-old system that relies on self-reported cases from patients and health care providers.
The reports of the condition grew worrisome enough in recent weeks that federal officials determined they needed to call an emergency meeting of the C.D.C. advisers.
In April, soon after Johnson & Johnson’s vaccine started being administered in the United States, federal officials briefly recommended halting use of the shot because of concerns about the risk of blood clots. At the time, the condition had emerged in six women, all of whom developed the illness within one to three weeks of vaccination. One of the women had died. By May, 28 cases had been confirmed.
The updated F.D.A. fact sheet for providers says that “currently available evidence supports a causal relationship” between the condition and Johnson & Johnson’s vaccine.
The new data come during a surge in virus cases driven by the Delta coronavirus variant and Omicron, the version of the virus that has already become dominant in some countries and is spreading fast in the United States.
Several laboratory experiments suggest that a single dose of Johnson & Johnson’s shot may offer little defense against infection with Omicron. The company said late last month that it is testing blood samples from clinical trial participants who have received its shot as a booster to see how their vaccine-induced antibodies fare against Omicron.
The shot has largely fallen out of favor in the United States, despite early hopes that its one-and-done format would be easy to deploy in more isolated communities, and among people skittish about receiving two doses.
Federal health officials in October authorized booster shots for people who had received a single shot of Johnson & Johnson vaccine at least two months earlier. They allowed for a “mix and match” approach, allowing people to get a second shot of a Pfizer or Moderna vaccine. Among people in the United States who originally received a single Johnson & Johnson shot and then got a second shot, fewer than 28 percent have gotten Johnson & Johnson as their booster.
Christina Jewett contributed reporting.