Bell’s Palsy, Other Rare Events Not Linked With COVID-19 Vaccines

A photo of a senior man suffering from Bell’s palsy over out of focus empty vaccine vials.

Immune-mediated neurologic events did not increase after COVID-19 vaccination, electronic health record data in the U.K. and Spain showed.

No safety signal was found between COVID-19 vaccines and Bell’s palsy, encephalomyelitis, Guillain-Barré syndrome, or transverse myelitis, reported Daniel Prieto-Alhambra, MD, PhD, of the University of Oxford in England, and co-authors.

However, rates of Bell’s palsy, encephalomyelitis, and Guillain-Barré syndrome were higher than expected after COVID-19 infection, the researchers wrote in The BMJ.

“Spontaneous reports of Guillain-Barré and other immune-mediated neurological conditions led to the investigation of these as potential side effects associated with some COVID vaccines,” Prieto-Alhambra told MedPage Today.

“We wanted to research this using clinical data from well-curated data sources,” he said. “In addition, we wanted to investigate if an association exists with COVID-19, as some previous research has suggested that viral infections can cause or trigger similar conditions.”

Both the FDA and the European Medicines Agency have listed Guillain-Barré syndrome, an acquired demyelinating polyneuropathy, as a very rare side effect of viral vector vaccines. Bell’s palsy, a facial nerve paralysis, has been shown to be more common in people with SARS-CoV-2 infection than in people vaccinated against the virus.

An earlier epidemiology study in England demonstrated that neurologic events were more common overall after a positive SARS-CoV-2 test than after vaccination, noted Anton Pottegård, DMSc, PhD, of the University of Southern Denmark in Odense, and Olaf Klungel, MSc, PhD, of Utrecht University in the Netherlands, in an accompanying editorial.

“Importantly, all risks — even those observed after SARS-CoV-2 infection — are small in absolute terms for the single individual,” the editorialists wrote. “Even small absolute risks can, however, lead to a substantial burden on the healthcare system in the context of mass vaccination and widespread infection.”

The findings of the current study and the previous one in England “are reassuring about the safety of the vaccines, particularly compared with the observed risks associated with SARS-CoV-2 infection,” Pottegård and Klungel continued. “Neither study should therefore lead to any changes in communications to the public about the positive benefit-risk balance of vaccines.”

“However, a specific and important communication challenge remains for individuals who develop a neurological complication shortly after vaccination, their families, and others hearing about their history,” the editorialists pointed out. “Reassuring them that the two events are likely unrelated will be difficult, even with the knowledge generated by these two large real-world studies.”

“Researchers and clinicians have a responsibility to discuss these findings with affected patients and their families, while at the same time acknowledging the inherent uncertainties in making patient-level inferences from population-level studies,” Pottegård and Klungel added.

For the study, Prieto-Alhambra and co-authors reviewed primary care records in the U.K., and primary care and linked hospital data in Spain. They included more than 8.3 million people who received at least one dose of Pfizer-BioNTech (Comirnaty), Moderna (SpikeVax), Johnson & Johnson, or AstraZeneca COVID-19 vaccines between the rollout of the vaccination campaigns and the end of data availability (May 2021 for U.K. data and June 2021 for Spain).

The researchers also studied nearly 736,000 unvaccinated individuals with a first positive reverse transcription polymerase chain reaction test result for SARS-CoV-2 after September 2020, and about 14.3 million people in the general population.

Outcomes were the incidence of Bell’s palsy, encephalomyelitis, Guillain-Barré syndrome, or transverse myelitis in 21 days after the first vaccine shot, 90 days after a positive COVID test, or between 2017 and 2019 to determine background rates in the general population cohort.

Overall, about 3.6 million people received Pfizer, 4.4 million received AstraZeneca, 245,000 received Moderna, and 121,000 received Johnson & Johnson vaccines.

Post-vaccine rates were consistent with background rates for Bell’s palsy, encephalomyelitis, and Guillain-Barré syndrome. The researchers noted that due to limited statistical power, they conducted a self-controlled case series only for Bell’s palsy and found no safety signal among people who were vaccinated.

The rates of immune-mediated neurologic events were higher than expected after COVID infection. In the U.K., standardized incidence ratios after infection were 1.33 (95% CI 1.02-1.74) for Bell’s palsy, 6.89 (95% CI 3.82-12.44) for encephalomyelitis, and 3.53 (95% CI 1.83-6.77) for Guillain-Barré.

In Spain, standardized post-infection incidence ratios were 1.70 (95% CI 1.39-2.08) for Bell’s palsy, 3.75 (95% CI 2.55-6.02) for encephalomyelitis, and 5.92 (95% CI 3.98-9.53) for Guillain-Barré. Fewer than five transverse myelitis events occurred among vaccinated people in each country.

The study had several limitations, Prieto-Alhambra and co-authors noted. It did not include hospital records in the U.K. and may have missed some immune-mediated neurologic disorders. Confounding by indication also may have influenced the historical comparator analysis. “Although we account for differences in age, individuals vaccinated also had more comorbidities than the comparator cohort and may well differ in other, unobserved characteristics,” the researchers acknowledged. They added that people with a recent history of the same immune-mediated neurologic events were excluded from the study and the findings do not apply to individuals with chronic relapsing conditions like multiple sclerosis.

  • Judy George covers neurology and neuroscience news for MedPage Today, writing about brain aging, Alzheimer’s, dementia, MS, rare diseases, epilepsy, autism, headache, stroke, Parkinson’s, ALS, concussion, CTE, sleep, pain, and more.


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