F.D.A. Attaches Warning of Rare Nerve Syndrome to Johnson & Johnson Covid Vaccine

The Food and Drug Administration warned on Monday that Johnson & Johnson’s coronavirus vaccine can lead to an increased risk of a rare neurological condition known as Guillain–Barré syndrome, another setback for a vaccine that has largely been sidelined in the United States.

Although regulators have found that the chances of developing the condition are low, they appear to be three to five times higher among recipients of the Johnson & Johnson vaccine than among the general population in the United States, according to people familiar with the decision. The warning was attached to fact sheets about the vaccine for providers and patients.

Federal officials have identified 100 suspected cases of Guillain-Barré among recipients of Johnson & Johnson’s one-dose shot through a federal monitoring system that relies on patients and health care providers to report adverse effects of vaccines. Ninety-five percent of those cases were considered serious and required hospitalization, the Food and Drug Administration said. The reports are preliminary.

In a statement, the agency said that while “the available evidence suggests an association” between the Johnson & Johnson vaccine and increased risk of Guillain–Barré syndrome, “it is insufficient to establish a causal relationship.”

The agency added that it “continues to find the known and potential benefits clearly outweigh the known and potential risks” of the vaccine.

About 12.8 million people — or about 8 percent of the fully vaccinated population in the United States — have received the Johnson & Johnson shot. By contrast, about 146 million have been fully vaccinated with Pfizer’s or Moderna’s vaccines, both of which require two doses.

Guillain-Barré syndrome occurs when the immune system damages nerve cells, causing muscle weakness and occasional paralysis, according to the Food and Drug Administration. Several thousand people — about 10 out of every million — develop the condition every year in the United States. Most recover from even severe symptoms.

“What worries me most is that it reinforces the lack of confidence that people had,” said Dr. Steven Black, an emeritus professor of pediatrics at Cincinnati Children’s Hospital Medical Center and the co-director of the Global Vaccine Data Network, a consortium that researches the safety of vaccines. “They’ll say, ‘Aha, see, I was right.’ But they’re not right.”

The risk is low enough, he added, that “for people trying to make a rational decision, this should not influence their decision to get vaccinated.”

The suspected cases were reported to the Vaccine Adverse Event Reporting System, a 30-year-old federal monitoring system. In a statement released on Monday, the Centers for Disease Control and Prevention said the cases were mostly reported about two weeks after vaccination and mostly in men, many of them ages 50 years and older.

Johnson & Johnson said in a statement that “the risk of having this occur is very low, and the rate of reported cases exceeds the background rate by a small degree.”

Guillain-Barré syndrome has previously been linked to other vaccines, including the 1976 swine flu vaccine and other flu vaccines. Some studies suggested that people were more likely to develop Guillain-Barré from the flu than from flu vaccines, which are monitored every year by the C.D.C. for any associations with the condition. The Food and Drug Administration warned this year that GlaxoSmithKline’s shingles vaccine, Shingrix, could also increase the risk of the disease.

The warning is the second that the agency has issued for the Johnson & Johnson vaccine: In April, it warned of an increased risk of blood clots coupled with low platelets, components of blood that normally help to heal wounds. The warning came after a 10-day pause in administering the shot, during which officials investigated a small spate of such cases among women.

Federal regulators called for the pause because unlike the reports of Guillian-Barré syndrome, the authorities learned that the blood clots had caused several deaths, and that some physicians were prescribing the wrong treatment for patients.

The database indicates only one possible death of a recipient of the Johnson & Johnson shot from Guillain-Barré syndrome. But the man, a 57-year-old from Delaware, had also had a heart attack and a stroke in the past four years, raising questions about what led to his death in April.

Even though it requires only one dose and is easier to store than Pfizer’s and Moderna’s vaccines, Johnson & Johnson’s shot has played only a minor role in the U.S. inoculation campaign. That is partly because a plant in Baltimore that was supposed to supply most of the doses in the country was shut down for three months because of regulatory violations. The factory, operated by Emergent BioSolutions, a subcontractor, has been forced to throw out the equivalent of 75 million doses because of suspected contamination, significantly delaying deliveries to the federal government.

At the same time, demand for the shot plummeted after the safety pause in April. At that time, 15 women in the United States and Europe who had received the Johnson & Johnson shot were diagnosed with the clotting disorder; three died. The C.D.C. has now confirmed 38 cases of the disorder.

Regulators and federal health officials warned that women younger than 50, in particular, should be aware of the “rare but increased” clotting risk. But in the nearly three months since the pause ended, only about five million people in the United States have taken Johnson & Johnson’s shot, and state officials report that people are much more wary of it. Millions of doses that have been distributed by the federal government are sitting unused and will expire this summer.

Alex Gorsky, Johnson & Johnson’s chief executive, said last month that he was still hopeful that the vaccine, which has been used in 27 countries, would help contain the pandemic overseas. The company has promised up to 400 million doses to the African Union. Separately, Covax, the global vaccine-sharing program, is supposed to receive hundreds of millions of doses.

Studies have showed that the Johnson & Johnson shot protects people against more contagious coronavirus variants, including the Delta variant, and is highly effective at preventing severe Covid-19, hospitalizations and death.

The Food and Drug Administration shares jurisdiction over vaccines with the C.D.C., but it is solely responsible for issuing product warnings. The Guillain-Barré cases will be discussed in an upcoming meeting of a committee of outside experts who advise the C.D.C., the agency said.

Federal regulators also attached warnings to the Pfizer-BioNTech and Moderna vaccines, but some government health officials described them as less serious than the warnings about Johnson & Johnson. The agency last month pointed to an increased risk of inflammation of the heart or the tissue surrounding it — diseases known as myocarditis and pericarditis — particularly among adolescents and young adults who had received Pfizer-BioNTech or Moderna shots.

The C.D.C. said that in most of the reported cases, symptoms promptly improved after rest or medication. By contrast, symptoms of Guillian-Barré typically require medical intervention, officials said.

The revised fact sheet for Johnson & Johnson’s shot states that recipients should immediately seek medical attention if they develop any of the following symptoms: weakness or tingling sensations, especially in the legs or arms, that worsens and spreads to other parts of the body; difficulty walking; difficulty with facial movements, including speaking, chewing or swallowing; double vision or inability to move eyes; or difficulty with bladder control or bowel function.

Apoorva Mandavilli and Carl Zimmer contributed reporting.