Messenger RNA Coronavirus Disease 2019 (COVID-19) Vaccination With BNT162b2 Increased Risk of Bell's Palsy: A Nested Case-Control and Self-Controlled Case Series Study.

Background: Observable symptoms of Bell's palsy following vaccinations arouse concern over the safety profiles of novel coronavirus disease 2019 (COVID-19) vaccines. However, there are only inconclusive findings on Bell's palsy following messenger (mRNA) COVID-19 vaccination. This study aims to update the previous analyses on the risk of Bell's palsy following mRNA (BNT162b2) COVID-19 vaccination.
Methods: This study included cases aged ≥16 years with a new diagnosis of Bell's palsy within 28 days after BNT162b2 vaccinations from the population-based electronic health records in Hong Kong. Nested case-control and self-controlled case series (SCCS) analyses were used, where the association between Bell's palsy and BNT162b2 was evaluated using conditional logistic and Poisson regression, respectively.
Results: Totally 54 individuals were newly diagnosed with Bell's palsy after BNT162b2 vaccinations. The incidence of Bell's palsy was 1.58 (95% confidence interval [CI], 1.19-2.07) per 100 000 doses administered. The nested case-control analysis showed significant association between BNT162b2 vaccinations and Bell's palsy (adjusted odds ratio [aOR], 1.543; 95% CI, 1.123-2.121), with up to 1.112 excess events per 100 000 people who received 2 doses of BNT162b2. An increased risk of Bell's palsy was observed during the first 14 days after the second dose of BNT162b2 in both nested case-control (aOR, 2.325; 95% CI, 1.414-3.821) and SCCS analysis (adjusted incidence rate ratio, 2.44; 95% CI, 1.32-4.50).
Conclusions: There was an overall increased risk of Bell's palsy following BNT162b2 vaccination, particularly within the first 14 days after the second dose, but the absolute risk was very low.
Competing Interests: Potential conflicts of interest. E. Y. F. W. has received research grants from the Food and Health Bureau of the Government of the HKSAR and the Hong Kong Research Grants Council (RGC), outside the submitted work. C. S. L. C. has received grants from the Food and Health Bureau of the Hong Kong Government, Hong Kong RGC, Hong Kong Innovation and Technology Commission, Pfizer, IQVIA, and Amgen (all paid to institution) and a personal fee from Primevigilance Ltd, outside the submitted work. E. W. Y. C. reports honorarium from the Hospital Authority and grants from the Hong Kong RGC, Research Fund Secretariat of the Food and Health Bureau, National Natural Science Fund of China, Wellcome Trust, Bayer, Bristol-Myers Squibb, Pfizer, Janssen, Amgen, Takeda, and the Narcotics Division of the Security Bureau of HKSAR, outside the submitted work (no payments from Wellcome Trust, all other payments to institution). F. T. T. L. has been supported by the RGC Postdoctoral Fellowship under the Hong Kong RGC (paid to institution Chinese University of Hong Kong) and has received research grants from the Food and Health Bureau of the Government of the HKSAR, outside the submitted work. X. L. has received research grants from the Food and Health Bureau of the Government of the HKSAR, RGC Early Career Scheme, and RGC Research Matching Grant Scheme; research and educational grants from Janssen and Pfizer (all paid to institution); internal funding from the University of Hong Kong; a consultancy fee from Merck Sharp & Dohme, paid to author and unrelated to this work; and payment to author for lectures, presentations, speakers bureaus, manuscript writing, and educational events from Pfizer. K. K. L. received grants from the Research Fund Secretariat of the Food and Health Bureau, Innovation and Technology Bureau, RGC, Amgen, Boehringer Ingelheim, Eisai, and Pfizer and consultation fees from Amgen, Boehringer Ingelheim, Daiichi Sankyo, and Sanofi, all outside the submitted work. B. J. C. received consulting fees paid to author from AstraZeneca, Fosun Pharma, GSK, Moderna, Pfizer, Roche, and Sanofi Pasteur. I. F. N. H. received speaker fees from MSD for the COVID-19 Regional Expert Input Forum 2021 and Herpes Zoster Lecture 2021. I. C. K. W. reports research funding outside the submitted work from Amgen, Bristol-Myers Squibb, Pfizer, Janssen, Bayer, GSK, Novartis, the Hong Kong RGC, the Hong Kong Health and Medical Research Fund, the National Institute for Health Research in England, European Commission, National Health and Medical Research Council in Australia, Narcotics Division of the Security Bureau of HKSAR, and the Wellcome Trust; received speaker fees paid to author from Janssen, Medice, and Amgen; and is an independent nonexecutive director of Jacobson Medical in Hong Kong. C. K. H. W. has received grants or contracts paid to institution from Health and Medical Research Fund, Food and Health Bureau, HKSAR Government, General Research Fund, RGC, HKSAR Government, and Euroqol Research Foundation. All remaining authors: No reported conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
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