Association of SARS-CoV-2 Vaccination or Infection With Bell Palsy: A Systematic Review and Meta-analysis

Abstract

Importance: Bell palsy (BP) has been reported as an adverse event following the SARS-CoV-2 vaccination, but neither a causative relationship nor a higher prevalence than in the general population has been established.

Objective: To compare the incidence of BP in SARS-CoV-2 vaccine recipients vs unvaccinated individuals or placebo recipients.

Data sources: A systematic search of MEDLINE (via PubMed), Web of Science, Scopus, Cochrane Library, and Google Scholar from the inception of the COVID-19 report (December 2019) to August 15, 2022.

Study selection: Articles reporting BP incidence with SARS-CoV-2 vaccination were included.

Data extraction and synthesis: This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline and was conducted with the random- and fixed-effect models using the Mantel-Haenszel method. The quality of the studies was evaluated by the Newcastle-Ottawa Scale.

Main outcomes and measures: The outcomes of interest were to compare BP incidence among (1) SARS-CoV-2 vaccine recipients, (2) nonrecipients in the placebo or unvaccinated cohorts, (3) different types of SARS-CoV-2 vaccines, and (4) SARS-CoV-2-infected vs SARS-CoV-2-vaccinated individuals.

Results: Fifty studies were included, of which 17 entered the quantitative synthesis. Pooling 4 phase 3 randomized clinical trials showed significantly higher BP in recipients of SARS-CoV-2 vaccines (77 525 vaccine recipients vs 66 682 placebo recipients; odds ratio [OR], 3.00; 95% CI, 1.10-8.18; I2 = 0%). There was, however, no significant increase in BP after administration of the messenger RNA SARS-CoV-2 vaccine in pooling 8 observational studies (13 518 026 doses vs 13 510 701 unvaccinated; OR, 0.70; 95% CI, 0.42-1.16; I2 = 94%). 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; 95% CI, 0.82-1.15; I2 = 0%). 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; 95% CI, 1.57-6.62; I2 = 95%).

Conclusions and relevance: This systematic review and meta-analysis suggests a higher incidence of BP among SARS-CoV-2-vaccinated vs placebo groups. The occurrence of BP did not differ significantly between recipients of the Pfizer/BioNTech vs Oxford/AstraZeneca vaccines. SARS-CoV-2 infection posed a significantly greater risk for BP than SARS-CoV-2 vaccination.

Figure 1.. Bell Palsy Events in Groups of Vaccine Recipients vs Saline Placebo Recipients, With Data From Randomized Clinical Trials

Dashed line indicates the point estimate of the overall effect; dotted line, no effect; diamonds, overall effects. OR indicates odds ratio.

Figure 2.. Bell Palsy Events in Groups of mRNA-Vaccinated Participants vs Unvaccinated Participants, With Data From Observational Studies

Dashed line indicates the point estimate of the overall effect; dotted line, no effect; diamonds, overall effects. mRNA indicates messenger RNA; OR, odds ratio.

Figure 3.. Bell Palsy Events in Groups of Pfizer/BioNTech Recipients vs Oxford/AstraZeneca Recipients, With Data From Observational Studies

Dashed line indicates the point estimate of the overall effect; dotted line, no effect; diamond, overall effect. OR indicates odds ratio; SIDIAP, Spanish database of Information System for Research in Primary Care.

Figure 4.. Bell Palsy in Groups of SARS-CoV-2 Infection vs SARS-CoV-2 Vaccine Recipients, With Data From Observational Studies

Dotted line indicates no effect; diamond, overall effect. RR indicates risk ratio; SIDIAP, Spanish database of Information System for Research in Primary Care.