The shingles vaccine Shingrix can also increase your risk of developing shingles.

It’s not entirely clear why some vaccines can cause Guillain-Barré. “We don’t really understand the biological mechanism,” said Salmon. “It’s an incredible frustration.”

One hundred reports of Johnson & Johnson’s post-injection syndrome have been submitted to the state’s Vaccine Adverse Event Reporting System (VAERS), authorities said Monday. Of these, 95 cases resulted in hospitalization, one of which was fatal.

The syndrome was typically reported about two weeks after vaccination, mostly in men, many of whom were 50 years of age or older, authorities said. There isn’t enough evidence yet to determine that the vaccine is causing the disease, but the FDA will continue to monitor the situation, the agency said in a statement.

There is still no data to suggest a link between the disease and COVID-19 vaccines from Pfizer-BioNTech or Moderna, which are based on another technology, the FDA said.

The syndrome most likely occurs within 42 days of vaccination, the FDA notes in their revised patient information sheet. You should see a doctor if you experience weakness or tingling in your arms and legs, double vision, or difficulty walking, speaking, chewing, swallowing, or controlling your bladder or bowel.

If the relationship between the vaccine and Guillain-Barré is real, the risks of COVID-19 seem to far outweigh the risks, experts say. In the United States, almost all COVID-19 hospital admissions and deaths occur in people who are not vaccinated, the CDC said in a statement. The agency recommends that everyone over the age of 12 get vaccinated.