According to The Washington Post, the Food and Drug Administration (FDA) issued a new warning for the Johnson & Johnson coronavirus vaccine on Monday, claiming that the shot has been linked to a serious but uncommon side effect called Guillain-Barré syndrome, in which the immune system attacks the nerves.

According to a companion statement from the Centers for Disease Control and Prevention (CDC), which monitors vaccine safety systems with the FDA, about 100 preliminary reports of Guillain-Barré syndrome have been detected in vaccine recipients after the administration of 12.8 million doses of Johnson & Johnson vaccine in the United States.

According to the FDA statement, 95 of these cases were serious enough to necessitate hospitalization. Only one person died. Neither agency gave any information concerning the death.

According to the CDC, the instances have generally been documented two weeks after immunization and are mostly in men, many of whom are 50 and older. Guillain-Barré syndrome is usually reversible.

Although existing information implies a link between the Johnson & Johnson vaccination and an elevated risk of Guillain-Barré, the FDA stated that the evidence is insufficient to establish a causative relationship.

Johnson & Johnson did not respond to a request for comment.

The Johnson & Johnson COVID-19 vaccine, which requires only one dosage rather than two, was approved by the FDA in late February, but the vaccine has been plagued by issues, including mishaps at its US manufacturing site.

The FDA informed Johnson & Johnson last month that millions of doses of its vaccine made at a troubled plant in Baltimore could not be used due to contamination concerns.

Several weeks after it was discovered that batches of substance used to make the J&J vaccine were cross-contaminated with ingredients from the AstraZeneca vaccine, the Emergent factory was instructed to halt production, resulting in the loss of 15 million J&J doses.

According to The Washington Post, available data do not indicate a trend showing a similar higher risk of Guillain-Barré with the Pfizer-BioNTech and Moderna vaccines.