Baltimore, MD—A recent systematic review and meta-analysis identified a link between a higher incidence of Bell’s palsy (BP) among recipients of SARS-CoV-2–vaccines versus placebo groups.

Johns Hopkins University–led researchers emphasized, however, that COVID-19 infection confers a significantly greater risk for BP than vaccination. They also pointed out that occurrence of BP did not differ significantly between recipients of the Pfizer/BioNTech mRNA vaccine compared with those getting Oxford/AstraZeneca vaccines.

BP is an unexplained episode of facial muscle weakness or paralysis that begins suddenly and worsens over 48 hours. It is linked to damage to the seventh cranial nerve, with pain and discomfort usually occurring on one side of the face or head.

In a report in the Journal of the American Medical Association Otolaryngology-Head & Neck Surgery, the study team described how it performed a systematic search of MEDLINE (via PubMed), Web of Science, Scopus, Cochrane Library, and Google Scholar from the inception of the COVID-19 report from December 2019 to August 15, 2022. Articles reporting BP incidence with SARS-CoV-2 vaccination were included.

The authors compared BP incidence among the following groups and situations:

• SARS-CoV-2 vaccine recipients
• Nonrecipients in the placebo or unvaccinated cohorts
• Different types of SARS-CoV-2 vaccines
• SARS-CoV-2–infected versus SARS-CoV-2–vaccinated individuals.

Of the 50 studies included, 17 were part of the quantitative synthesis. Based on pooling four phase III randomized clinical trials, researchers say they found significantly higher BP rates 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%),” the authors wrote. “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%).”

On the other hand, the study notes that BP was much more common after SARS-CoV-2 infection (the group with 2,822,072 participants) than after SARS-CoV-2 vaccinations (the group with 37,912,410 participant; relative risk 3.23; 95% CI, 1.57-6.62; I2 = 95%).

“To the best of our knowledge, this is the first systematic review and meta-analysis addressing the incidence of BP subsequent to SARS-CoV-2 vaccination,” the authors wrote, adding, “This study has pooled data on more than 53 million vaccine doses for meta-analysis. In this context, we have compared 2 major SARS-CoV-2 vaccine platforms in terms of BP occurrence in more than 50 million doses. The BP occurrence following SARS-CoV-2 infection was also compared with receipt of the SARS-CoV-2 vaccine in approximately 40 million individuals.”

The researchers emphasized that, although their study indicates evidence of increased BP incidence following SARS-CoV-2 vaccination compared with placebo receipt, SARS-CoV-2 infection was associated with a 3.23-fold increase in BP incidence, “thus, our results suggest that vaccinating against SARS-CoV-2 can significantly diminish the odds of BP compared with SARS-CoV-2 infection.”

The researchers added, “Considering that the overall BP incidence is approximately 15 to 30 per 100,000 annually in the general population, our analysis of RCTs suggests a similar BP incidence of 18 per 100,000 among SARS-CoV-2 vaccine recipients. This rate is comparable with the previous reports with an incidence of 19 or lower per 100,000 population after SARS-CoV-2 vaccination. With SARS-CoV-2 infection, however, the reported BP incidence is significantly higher at 32.3 to 82 per 100,000 patients. These results overall suggest that the BP incidence after SARS-CoV-2 vaccines is comparable with the overall incidence in the general population, whereas it clearly exceeds that with SARS-CoV-2 infection.”

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