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Johnson & Johnson’s Covid-19 vaccine may trigger a rare neurological condition in a small number of people who receive the vaccine, the Food and Drug Administration said Monday.

Reports to a database operated jointly by the agency and the Centers for Disease Prevention and Control suggest there may be a link between the inoculations and Guillain-Barré syndrome, a form of progressive paralysis that is generally reversible, the FDA said in a statement.


The agency said there have been about 100 preliminary reports of GBS, as the condition is often called, in people who have received the J&J vaccine. To date, about 12.8 million doses of the J&J vaccine have been used in the United States, suggesting a rate of about one case of GBS per 128,000 people vaccinated.

In most cases, the people reporting the condition developed it about two weeks after receiving the one-dose vaccine. Most are older males, which fits with the known pattern of GBS, said John Moore, an immunologist at Weill Cornell Medicine.

“A rare, but very probably real consequence of the vaccine,” said Paul Offit, a vaccine expert from Children’s Hospital of Philadelphia. “Again, the benefits of the vaccine clearly and definitely outweigh its very rare risks.”


The FDA’s statement comes after a similar signal of GBS was identified with AstraZeneca’s Covid vaccine. Last week the European Medicines Agency’s Pharmacovigilance Risk Assessment Committee recommended adding a warning to the label of the AstraZeneca vaccine, Vaxzevria, to inform health care providers. Its statement said it is not currently clear if the AstraZeneca vaccine triggers the condition. “At this stage the available data neither confirms nor rules out a possible association with the vaccine,” the EMA said.

Both the AstraZeneca and J&J vaccines are what are known as viral-vectored vaccines — meaning they carry harmless genetic material from the SARS-CoV-2 virus into the body to trigger an immune response. The fact that both these vaccines now appear to be associated with GBS suggest it could be a class effect — something one might expect to see with other viral-vectored Covid vaccines, Offit said.

The FDA said to date there has been no signal to suggest the messenger RNA vaccines — those made by Moderna or Pfizer and its partner BioNTech — trigger GBS.

There are multiple known causes of Guillain-Barré syndrome. Some viral infections, including influenza, have been shown to increase one’s risk of developing GBS, as have some gastrointestinal infections. And several vaccines have been shown to, on rare occasions, induce the condition.

Most famously, the 1976 swine flu vaccination program in the United States was halted after a number of cases of Guillain-Barré syndrome were reported in people who received the vaccine. It was later estimated that the syndrome occurred at a rate of about one case per 100,000 doses of the swine flu vaccine. Though some flu seasons there is no signal of increased GBS cases linked to vaccination, other years there does appear to be an increase. In those cases, it has been estimated that there are one or two additional cases of GBS for every 1 million doses of vaccine given, the CDC estimates.

Between 3,000 and 6,000 people in the United States develop GBS every year. The underlying cause of the condition causes nerve inflammation that can result in pain, numbness, muscle weakness, and difficulty walking.

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