Bell's palsy following vaccination with Pfizer-BioNTech mRNA and inactivated (CoronaVac) SARS-CoV-2 vaccine

06/09/2021

On 16 August, a study was published assessing the risk of Bell's palsy following vaccination with Pfizer-BioNTech and CoronaVac BNT162b2 vaccines, using data from the COVID-19 Vaccine Adverse Event Reporting system in Hong Kong, and a nested case-control study. 

Between 23 February and 4 May 2021, 451,939 people received a first dose of the CoronaVac vaccine, and 537,205 people received a first dose of BNT162b2. There were 28 clinically confirmed reports to the Hong Kong adverse event reporting system of cases of Bell's palsy after administration of the CoronaVac vaccine, and 16 reported cases after administration of the BNT162b2 vaccine. The age-standardized incidence of clinically confirmed cases of Bell's palsy following vaccination with the CoronaVac vaccine was 66.9 cases per 100,000 people/year (95% CI 37.2 to 96.6)  and 42.8 per 100,000 people/year (95% CI 19.4 to 66.1) for those who had received the BNT162b2 vaccine. The age-standardized difference for the incidence compared with the background population was 41.5 (95% CI 11·7 to 71·4) for CoronaVac and 17.0 (95% CI −6·6 to 40.6) for BNT162b2, equivalent to an additional 4.8 cases per 100,000 people vaccinated for CoronaVac and 2.0 cases per 100,000 people vaccinated for BNT162b2.  

A nested case-control study using conditional logistic regression was also conducted to estimate the odds ratio (OR) for the risk of Bell's palsy and vaccination. Cases and controls were matched (1:4) by age, sex, place, and date of admission. In the nested case-control analysis, 298 cases were matched to 1,181 controls, and the adjusted ORs were 2.385 (95% CI 1.415 to 4.022) for CoronaVac and 1.755 (95% CI 0.886 to 3.477) for BNT162b2. These findings suggest an overall increased risk of Bell's palsy following vaccination with the CoronaVac vaccine. However, the beneficial and protective effects of the inactivated COVID-19 vaccine far outweigh the risk of this generally selflimiting adverse event. Additional studies are needed to confirm these findings.

Source: Bell's palsy following vaccination with mRNA (BNT162b2) and inactivated (CoronaVac) SARS-CoV-2 vaccines: a case series and nested case-control study. The Lancet. Published: 16 August 2021. https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(21)00451-5/fulltext

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