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No data linking COVID-19 vaccine to stiff person syndrome

December 19, 2022 GMT

CLAIM: A Pfizer document shows stiff person syndrome in a list of adverse events, suggesting the condition is caused by the COVID-19 vaccine.

AP’S ASSESSMENT: Missing context. Experts say there is no established link between the rare neurological disorder and COVID-19 vaccination. A Pfizer document includes the condition in a list of medical events reported by some vaccine recipients, which are recorded regardless of whether the vaccine caused the event. Neither the document nor any available data have shown the vaccine causes stiff person syndrome, experts say.

THE FACTS: Social media users are falsely suggesting that a Pfizer document proves the company’s COVID-19 vaccine causes stiff person syndrome, a medical condition that has gained attention after singer Celine Dion announced she was diagnosed with the disorder and had to cancel a tour.

“You will never guess what’s in Pf**er’s own documents,” reads text overlaid on a screenshot of the document posted to Instagram. The image shows circles around “Stiff person syndrome.”

Dion’s account is tagged in the post’s caption, which says the screenshot was taken from a Pfizer “adverse reaction document.”

But both Pfizer and experts say there has not been a relationship established between the COVID-19 vaccine and stiff person syndrome.

“At this time, our ongoing review and analysis has not identified ‘stiff person syndrome’ as having a causal association with the COVID-19 vaccine,” Pfizer spokesperson Keanna Ghazvini told The Associated Press in an email.

Dr. Scott Newsome, director of the Stiff Person Syndrome Center at the Johns Hopkins Hospital, similarly said in a statement that there is no support for the claim that the vaccine causes the ailment.

“The short answer is, there is no data or evidence to suggest that the COVID-19 vaccine causes Stiff Person Syndrome,” said Newsome, who is also an associate professor of neurology at Johns Hopkins. “This is also the case for other vaccines.”

Stiff person syndrome causes rigid muscles and painful muscle spasms, which can be triggered by such things as loud noises or light touch, the AP has reported. The cause isn’t known but it is thought to be an autoimmune disorder. Severe cases can cause difficulty walking and hunched posture.

The screenshot shared on Instagram comes from a Pfizer COVID-19 vaccine document that was uploaded online by an outside group and is titled, “5.3.6 CUMULATIVE ANALYSIS OF POST-AUTHORIZATION ADVERSE EVENT REPORTS OF PF-07302048 (BNT162B2) RECEIVED THROUGH 28-FEB-2021.”

Stiff person syndrome appears in an appendix labeled “LIST OF ADVERSE EVENTS OF SPECIAL INTEREST.”

But that doesn’t mean all of the conditions contained in the list have been proven to be side effects of the COVID-19 vaccine.

Instead, the document shows Pfizer tracking adverse events reported by vaccine recipients — which is routine — regardless of whether the vaccine caused the events, said Dr. Shobha Swaminathan, an associate professor of infectious diseases at Rutgers New Jersey Medical School. Swaminathan has helped lead a clinical trial site at the university for rival Moderna’s COVID-19 vaccine since 2020.

“The good thing is to be as transparent as possible and report everything and do an analysis to see if there’s a higher rate of any specific event among the group that got a product compared to the group that didn’t or compared to the background rate,” Swaminathan said. “Just because you get a vaccine doesn’t really mean that it’s actually causing it. You have to look to see, did it occur at a rate higher than what you would expect in the general population?”

Swaminathan said people might get a flu shot and experience pneumonia that winter, for example, but that doesn’t mean the pneumonia was caused by the vaccine.

“People are looking at events that are co-occurring and wrongly attributing that as causative,” she added.

Passive monitoring of COVID-19 vaccines is also done by the federal Vaccine Adverse Event Reporting System, whose unverified reports by the public have frequently been used to discredit COVID-19 vaccines despite disclaimers that the reports alone do not prove causation.

Attempts to reach a representative for Dion for comment were unsuccessful.


This is part of AP’s effort to address widely shared misinformation, including work with outside companies and organizations to add factual context to misleading content that is circulating online. Learn more about fact-checking at AP.