Is There a Link Between Bell Palsy and SARS-CoV-2 Infection, Vaccination?

SARS-CoV-2 vaccinations (both mRNA and viral vector vaccines), compared with placebo, are associated with a significantly increased risk of developing Bell palsy. However, compared with vaccination, SARS-CoV-2 infection tripled the risk for Bell palsy. These are the findings of a systematic review and meta-analysis published in JAMA Otolaryngology-Head & Neck Surgery.

A number of neurologic adverse events have been reported following SARS-CoV-2 vaccination, including Bell palsy, “although neither a causative relationship nor a prevalence of the condition higher than the general population has been established.” Bell palsy is described as the “sudden onset of facial paralysis or paresis due to facial nerve inflammation in the absence of central nervous system disease and after excluding the other causes of acute peripheral palsy.”

The management of Bell palsy involves the early use of corticosteroids, along with eye care for the prevention of corneal injury. In patients who experience the disorder, the efficacy of antiviral therapy has not been established. Although most cases of Bell palsy resolve within a few months, the severity of facial paralysis and a patient’s age may be predictive of a poor outcome.

Even though cases of Bell palsy have been reported following SARS-CoV-2 vaccination, neither a causative relationship nor a higher prevalence of the condition compared with the general population has been described.

For the study, researchers sought to compare the incidence of Bell palsy among recipients of SARS-CoV-2 vaccines vs unvaccinated individuals and placebo recipients. They conducted a systematic review from inception of the COVID-19 report in December 2019 through August 15, 2022.

The incidence of Bell palsy was determined by calculating the pooled effect estimates among the following sets of comparators:

• All phase 3 RCT-derived data on vaccine vs saline placebo recipients
• mRNA SARS-CoV-2 vaccine recipients vs unvaccinated participants in observational studies
• Pfizer/BioNTech vs Oxford/AstraZeneca SARS-CoV-2 vaccines
• SARS-CoV-2 infections vs SARS-CoV-2 vaccines

The outcome of interest was Bell palsy that occurred as an adverse event in the time frame following the vaccination, or the respective time frame in the unvaccinated matched participants or the placebo recipients. A diagnosis of Bell palsy was established by neurologist-confirmed clinical criteria and/or the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) codes.

A total of 50 studies were included:

• 22 case reports and case studies
• 2 self-controlled case series
• 2 case-control studies
• 3 cross-sectional studies
• 16 cohort studies
• 5 RCTs

The meta-analysis included 2 subgroups of mRNA vaccines (Pfizer/BioNTech and Moderna) and viral vector vaccines (Janssen and AstraZeneca).

The researchers found that in the mRNA vaccine subgroup, a significantly increased likelihood of Bell palsy was observed in the vaccinated group vs the placebo group (odds ratio [OR], 3.57; 95% CI, 1.09-11.67; Cochran Q P value = .46). In the viral vector vaccine subgroup, however, the results were not statistically significant (OR, 1.80; 95% CI, 0.26-12.35; Cochran Q P value = .89).

When the results of 4 phase 3 RCTs were pooled, significantly higher rates of Bell palsy were reported among recipients of SARS-CoV-2 vaccines (77,525 vaccine recipients vs 66,682 placebo recipients; OR, 3.00; 95% CI, 1.10-8.18).

When the results of 8 observational studies were pooled, however, no significant increase in the occurrence of Bell palsy was seen following administration of mRNA COVID-19 vaccines (13,518,026 vaccinated vs 13,510,701 unvaccinated individuals; OR, 0.70; 95% CI, 0.42-1.16).

No significant differences in incidence of Bell palsy were reported in 22,978,880 first-dose recipients of the Pfizer/BioNTech mRNA vaccine vs 22,978,880 first-dose recipients of the Oxford/AstraZeneca vaccine (OR, 0.97; 95% CI, 0.82-1.15).

The occurrence of Bell palsy was tripled following a COVID-19 infection — in 2,822,072 individuals — than following a SARS-CoV-2 vaccination — in 37,912,410 individuals (relative risk, 3.23; 95% CI, 1.57-6.62).

The study had several limitations, the researchers acknowledged. The researchers relied on previously published data and had no individual patient-level data. Also, only a small number of studies reported on the data of Bell palsy treatments and outcomes.

“SARS CoV-2 infection was linked with a 3.23-fold increased risk of BP [Bell palsy] compared with SARS-CoV-2 vaccines, which favors a protective role of the vaccine in reducing the incidence of BP associated with exposure to SARS-CoV-2,” the researchers concluded.