Fact check: Experts say there's no link between COVID-19 vaccine and stiff person syndrome

Hannah Hudnall, USA TODAY
·5 min read
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Vaccines sit at the ready at the Blue Shield of California Promise Health Plans' Community Resource Center where they were offering members and the public free flu and COVID-19 vaccines Friday, Oct. 28, 2022, in Lakewood.
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The claim: Stiff person syndrome is a 'known side effect' of Pfizer's COVID-19 vaccine

Celine Dion revealed earlier this month that she has been diagnosed with a neurological disorder called stiff person syndrome. The disease is extremely rare and causes progressive muscle stiffness and painful spasms, according to Johns Hopkins Medicine.

Some social media users are claiming the disease is a side effect of Pfizer's COVID-19 vaccine.

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"Celine Dion was disabled from a KNOWN SIDE EFFECT of the COVID vaccine -- 99.6% certainty," reads the title of a Dec. 15 Substack post.

The post, which was shared on Facebook more than 700 times in a week, came from Steve Kirsch, a tech millionaire and founder of the COVID-19 Early Treatment Fund who regularly spreads COVID-19 vaccine misinformation, according to MIT Technology Review.

A similar Instagram post implying the disease is an adverse reaction to the vaccine garnered more than 3,000 likes in 10 days. Similar versions of the claim have been shared on Instagram and Facebook.

The claim is false. Though Pfizer listed stiff person syndrome as an "adverse event of special interest" in a 2021 report, this doesn't mean the disease is a side effect of the vaccine. The company says it is monitoring adverse events closely, but they have not been proven to have a causal relationship with the vaccine.

Outside experts agree there is no proof the vaccine causes stiff person syndrome. Instead, this particular adverse event is known to be associated with severe cases of COVID-19, or with other vaccines in the past. Stiff person syndrome is not listed as an adverse reaction to the COVID-19 vaccine by the CDC or the Food and Drug Administration.

USA TODAY reached out to the social media user who shared the post for comment.

No proven link between stiff person syndrome and Pfizer vaccine

In his Substack post, Kirsch included a screenshot of a 2021 adverse reaction report published by Pfizer. Stiff person syndrome is included in the report's nine-page list of "adverse events of special interest."

Dr. Scott Newsome, director of Johns Hopkins' Stiff Person Syndrome Center, told USA TODAY in an email there is no data or evidence to suggest the COVID-19 vaccine causes the disease.

Pfizer's list of adverse events of special interest was compiled using data from several national databases including the Vaccine Adverse Event Reporting System (VAERS). The database, which is run by the Centers for Disease Control and Prevention, accepts and analyzes reports of possible adverse reactions to vaccines.

The CDC says on its website that anyone can submit a report to the system, meaning that "a report to VAERS does not mean that a vaccine caused an adverse event."

Newsome echoed this sentiment in his email to USA TODAY.

"Some people are using the VAERS for their evidence to support vaccines causing specific diseases," Newsome said. "The main confounder with this approach is that anyone can report cases to VAERS regardless of whether there is truly a causal relationship or just mere coincidence. Hence, it is important for people to examine what reporting system or data they are using to make claims on vaccines causing whatever they are putting out there.”

A spokesperson for Pfizer told USA TODAY in an email Pfizer's ongoing review has "not identified stiff person syndrome as having a causal association with our vaccine." The company is nonetheless monitoring all the listed adverse events of special interest.

"The document points out that we work with regulators around the world to agree to monitor for these particular adverse events very closely because they are either known to be associated with severe cases of COVID-19, or they have been known to be associated with other vaccines in the past," the spokesperson said.

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According to the National Institute of Neurological Disorders and Stroke, stiff person syndrome is ''the result of an autoimmune response gone awry in the brain and spinal cord.''

USA TODAY has previously debunked claims related to VAERS data, including the false claim that the death toll of COVID-19 vaccines is more than 20 times higher than that of past vaccines.

This claim was debunked by PolitiFact, Lead Stories, Reuters, the Associated Press and AFP as well.

Our rating: False

Based on our research, we rate FALSE the claim that stiff person syndrome is a "known side effect" of Pfizer's COVID-19 vaccine. Though Pfizer listed stiff person syndrome as an "adverse event of special interest," this doesn't mean the disease is a side effect of the vaccine. Experts say there is no evidence stiff person syndrome is a side effect of the vaccine.

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This article originally appeared on USA TODAY: Fact check: No, stiff person syndrome isn't caused by COVID-19 vaccine