Iran: A recent study published in JAMA Otolaryngology-Head & Neck Surgery has revealed an association between SARS-CoV-2 and Bell palsy (BP).
The systematic review and meta-analysis suggest a higher incidence of Bell palsy in those vaccinated against COVID-19 versus placebo groups. The researchers, however, found no significant difference between recipients of the Oxford/AstraZeneca versus Pfizer/BioNTech vaccine. Further, SARS-CoV-2 infection poses a significantly higher risk of BP than SARS-CoV-2 vaccination.

Notably, SARS-CoV-2 infection was tied to a 3.23-fold increased BP risk compared with SARS-CoV-2 vaccines, favouring the vaccine's protective role in reducing the BP incidence associated with exposure to SARS-CoV-2.
Bell palsy, idiopathic facial nerve palsy, is the most common cause of acute spontaneous peripheral facial paralysis. Its reported annual incidence rate is 15 to 30 cases per 100 000 population. There is no clarity on the exact cause of BP, but viral infections (such as herpes simplex virus), inflammation, and ischemia are some underlying mechanisms.
Bell palsy has also been reported as an adverse event after the SARS-CoV-2 vaccination. Still, studies have not been able to establish either a higher prevalence or a causative relationship than in the general population. Therefore, Ali Rafati, Iran University of Medical Sciences, Tehran, and colleagues aimed to compare the incidence of Bell palsy in the recipients of the SARS-CoV-2 vaccine versus unvaccinated individuals or placebo recipients.
For this purpose, the researchers searched the online databases from the inception of the COVID-19 report to August 15, 2022. Articles reporting the incidence of BP with SARS-CoV-2 vaccination were included.
The study's primary outcomes were to compare BP incidence among (!) recipients of SARS-CoV-2 vaccine, (2) nonrecipients in the unvaccinated or placebo cohorts, (3) different types of SARS-CoV-2 vaccines, and (4) SARS-CoV-2–infected versus SARS-CoV-2–vaccinated individuals.
The study led to the following findings:
Of the fifty studies included, 17 entered the quantitative synthesis.
Pooling 4 phase 3 randomized clinical trials revealed significantly greater BP in SARS-CoV-2 vaccine recipients (77 525 vaccine recipients vs 66 682 placebo recipients; odds ratio [OR], 3.00).
However, there was no significant increase in BP after administering the messenger RNA SARS-CoV-2 vaccine in pooling eight observational studies (13 518 026 doses vs 13 510 701 unvaccinated; OR, 0.70).
No significant difference was found in BP among 22 978 880 first-dose recipients of the Pfizer/BioNTech vaccine compared with 22 978 880 first-dose recipients of the Oxford/AstraZeneca vaccine (OR, 0.97).
Bell palsy was significantly more common after SARS-CoV-2 infection (n = 2 822 072) than after SARS-CoV-2 vaccinations (n = 37 912 410) (relative risk, 3.23).
"Our findings demonstrate evidence for the association between SARS-CoV-2 and BP; however, this finding does not equate to causality," the researchers conclude. "Further research is needed to validate this association and investigate possible mechanisms."
Reference:
Rafati A, Pasebani Y, Jameie M, et al. Association of SARS-CoV-2 Vaccination or Infection With Bell Palsy: A Systematic Review and Meta-analysis. JAMA Otolaryngol Head Neck Surg. Published online April 27, 2023. doi:10.1001/jamaoto.2023.0160