The association between COVID-19 vaccination and Bell's palsy

A closer look at these figures and analysis of crude real-world data from pharmacovigilance agencies estimated that Bell's palsy occurred more often in the mRNA vaccine groups than would be expected in the general population.8 Two research letters later provided indirect evidence for the safety of mRNA vaccines from a Bell's palsy standpoint. In one letter, the WHO pharmacovigilance database was used to show that mRNA COVID-19 vaccines did not confer an increased risk of facial paralysis when compared with other viral vaccines.9 In the other letter, the authors concluded that patients with COVID-19 have a greater risk of acquiring Bell's palsy than those who were vaccinated against the disease.10 The controversy was again addressed by the findings from a relatively small case-control study from Israel,11 in which 37 patients with Bell's palsy were matched to 74 controls and no association with mRNA-based SARS-CoV-2 vaccination was found (adjusted odds ratio [OR] for exposure 0·84 [95% CI 0·37–1·90; p=0·67]). Of note, hospital admissions due to facial nerve palsy in January and February, 2020, and January and February, 2021, were 29–112% greater than in the same period in the 5 preceding years, but this was not deemed significant.11 Wan and colleagues used different population-based approaches to evaluate the possible association between Bell's palsy and mRNA (BNT162b2; Fosun–BioNTech) and inactivated virus (CoronaVac) vaccines in Hong Kong.4 Using a voluntary surveillance reporting system and electronic health records, the authors found a substantial increase in the age-standardised incidence of Bell's palsy during the vaccination programme compared with the same period in previous years.