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UPDATE: AAO-HNS Statement on Bell’s Palsy Related to Approved COVID-19 Vaccines

UPDATE: AAO-HNS Statement on Bell’s Palsy Related to Approved COVID-19 Vaccines

UPDATE to AAO-HNS Statement on Bell’s Palsy Related to Approved COVID-19 Vaccines Issued December 19, 2020

In the AAO-HNS Statement on Bell’s Palsy Related to Approved COVID-19 Vaccines, when calculating the rate of vaccine induced Bell’s palsy (BP) from the Pfizer-BioNTech and Moderna vaccines, we assumed that the BP events found by 8 weeks (the median extent of the safety analysis) would encompass all the cases attributable to the vaccine for the remainder of the year. From the influenza literature, BP risk may extend only into the first 6-8 weeks after vaccination.[1] These calculations projected 17.7 cases per 100,000 per year attributable to the vaccine, which was then compared to the yearly background rate. Use of this statistic alone could be misleading.

  • The FDA Pfizer-BioNTech[2] and Moderna[3] vaccine reports found 6 cases of BP in the vaccinated cohort of 34,000 patients (this excludes the one case whose facial palsy may have been due to a stroke). This is greater than the 1.6 cases that would be expected to occur in 34,000 patients in an 8-week time period (assuming a BP background rate of 30 per 100,000 per year). However, the relatively small number of patients in the Pfizer and Moderna trials and the small number of BP cases did not provide enough data to determine significance.
  • According to the FDA Janssen vaccine briefing,[4] there were 2 reports of BP in the vaccinated cohort and 2 reports in the placebo cohort. Thus, even within the placebo cohort, the calculated incidence of BP reveals an unadjusted rate of 2 per 22,000 patients for 8 weeks or 59 per 100,000 per year, exceeding some values of assumed background BP rates.
  • There are many factors affecting BP rate, although the overall rate has been widely described in the literature, anywhere from 15, to 30, to 50 per 100,000.[5] It is a gross rate that disguises many nuances, including seasonality (potentially higher incidence in the winter), age, as well as comorbid factors (immune, autoimmune, neurologic comorbidities) that affect BP incidence amongst specific populations. The COVID-19 vaccine trials did not exclude these comorbidities from its participants.

The CDC maintains multiple vaccine safety monitoring programs including the Vaccine Adverse Event Reporting System (VAERS), the Vaccine Safety Datalink (VSD), V-safe, and the Clinical Immunization Safety Assessment (CISA) Project. These databases show low reports of BP events.

  • VAERS is a database that allows the public to self-report vaccine safety events. Query of the VAERES data base on March 24, 2021, returned 432 events for the symptoms “BELL’S PALSY,” “FACIAL PALSY,” and “FACIAL PARALYSIS” reported on vaccine products JANSSEN, MODERNA, and PFIZER-BIONTECH.[6] As a disclaimer, the CDC states that it is not possible to use VAERS data to calculate how often an adverse event occurs in a population or establish causality. Nonetheless, about 128 million doses have been given thus far in the United States, with 84 million individuals who have received at least one dose. Such numbers dwarf the number of BP cases reported in VAERS.
  • The VSD more robustly monitors pre-specified potential safety signals at 9 participating healthcare organizations including data from all healthcare encounters. As of February 13, 2021, data are available from 629,523 vaccinated individuals. The VSD reported 21 cases of Bell’s Palsy in vaccinated individuals. This compares to the 20.3 adjusted expected events among the unvaccinated comparators, thus indicating no increased risk.[7]

In summary, BP can be devastating. The CDC will continue surveillance for cases of BP as the vaccine is deployed into larger populations. However, the AAO-HNS feels these rare events should not dissuade healthcare personnel or patients from receiving these critical vaccines or strongly preferencing one vaccine over another. We certainly respect everyone’s right of choice in their medical treatment. As data accrues, we will hope to better ascertain associations—if any—between COVID-19 vaccinations and BP.

1. Committee to Review Adverse Effects of Vaccines; Institute of Medicine; Chapter 6: Influenza. In: Stratton K, Ford A, Rusch E, et al., eds. Adverse Effects of Vaccines: Evidence and Causality. National Academies Press. 2011:293-420. Accessed January 17, 2021.
2. FDA Briefing Document, Pfizer-BioNTech COVID-19 Vaccine. U.S. Food and Drug Administration website. Accessed January 11, 2021.
3. FDA Briefing Document, Moderna COVID-19 Vaccine. U.S. Food and Drug Administration website. Accessed January 11, 2021.
4. FDA Briefing Document, Janssen Ad26.COV2.S Vaccine for the Prevention of COVID-19. U.S. Food and Drug Administration website. Accessed March 24, 2021
5. Baugh RF, Basura GJ, Ishii LE, et al. Clinical practice guideline: Bell’s Palsy executive summary. Otolaryngol Head Neck Surg. 2013;149(5):656-663. doi:10.1177/0194599813506835
6. United States Department of Health and Human Services (DHHS), Public Health Services (PHS), Centers for Disease Control (CDC) / Food and Drug Administration (FDA), Vaccine Adverse Event Reporting System (VAERS) 1990 – 3/12/2021, CDC WONDER On-line Database. Accessed at on Mar 24, 2021 7:31:59 PM
7. COVID-19 Vaccine Safety Update, Advisory Committee on Immunization Practices, March 1, 2021, Centers for Disease Control and Prevention. Accessed March 29, 2021.

A special thank you to the collaborative work of the following AAO-HNS/F committee members on the development of this updated analysis:  CW David Chang, MD, Chair, Patient Safety and Quality Improvement (PSQI); Michael Brenner, MD, Chair, Outcomes Research and Evidence-Based Medicine; John D. Cramer, MD (PSQI);  Marc Bennet, MD, Chair, Otology and Neurotology Education Committee; and P. Daniel Knott, MD, Chair-Elect, Facial Plastic and Reconstructive Surgery Education Committee.

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