Johnson & Johnson vaccine linked to rare cases of autoimmune disorder

The Food and Drug Administration announced a change to the fact sheet on Johnson & Johnson's COVID-19 vaccine Monday, warning of an increased risk of Guillain-Barré syndrome, a neurological disorder that damages the nerves and can lead to paralysis.

"Based on an analysis of Vaccine Adverse Event Reporting (VAERS) data, there have been 100 preliminary reports following vaccination with the Janssen vaccine after approximately 12.5 million doses administered," an FDA spokesperson said in a statement to CNET. Ninety-five of the cases were serious and required hospitalization, with one reported death, according to the FDA.

The cases of Guillain-Barré usually occurred about two weeks after vaccination and were typically found in males aged 50 and older, according to a statement by the Centers for Disease Control and Prevention. The CDC said it will discuss the link between the US's only single-dose COVID vaccine and the autoimmune disorder at an upcoming meeting of the Advisory Committee on Immunization Practices. It also said that most people fully recover from Guillain-Barré syndrome.

The known benefits of Johnson & Johnson's COVID-19 vaccine continue to outweigh the known risks, the FDA said. But those who got a Johnson & Johnson shot should seek medical attention if they develop the following symptoms, per the FDA: weakness or tingling sensations, especially in the legs or arms, that's worsening and spreading 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.

In a statement, Johnson & Johnson said it's is in discussions with the FDA and other regulators about the link between its COVID-19 vaccine and Guillain-Barré syndrome. The company also said that the rate of reported cases of the syndrome "exceeds the background rate by a small degree." (The background rate is the number of cases that existed before the vaccine was introduced.)

The Guillain-Barré warning adds to a previous warning on Johnson & Johnson's COVID vaccine label about the risk of a rare but potentially deadly blood clotting disorder that also typically occurs about two weeks after vaccination, mostly in women under age 50.

Guillain-Barré can occur after infections with viruses such as the flu, Epstein Barr or Zika, the CDC reports. Guillain-Barré also occurs after infection with Campylobacter bacteria, which is the most common bacterial cause of diarrhea. It has also been been associated with other vaccines, such as those for the flu and shingles, according to the FDA. Although most people fully recover from Guillain-Barré syndrome, it can lead to severe nerve damage and paralysis. It's also most common in men and people over age 50. 

AstraZeneca, which is a similar vaccine to Johnson & Johnson, has also been linked to rare cases of Guillain-Barré syndrome, according to a June report by the American Neurological Association. Several cases of the syndrome were reported in people from India and England who had received AstraZeneca's COVID vaccine 10 to 22 days earlier, and cases were about 4 to 10 times more than the expected baseline frequency, researchers said.

Pfizer and Moderna have largely managed to avoid the drama that's plagued Johnson & Johnson (which includes suspected contamination of 75 million now-discarded doses of the vaccine at a Baltimore plant). However, both mRNA vaccines have been linked to cases of myocarditis, or heart inflammation, in men aged 30 and younger after their second dose of COVID vaccine. At a June meeting with the Advisory Committee on Immunization Practices, the CDC found that the benefits of the mRNA vaccines outweigh the risks in all age groups and that most cases of myocarditis are mild.