Rare Sudden Sensorineural Hearing Loss Potentially Associated With COVID-19 Vaccination Does Not Outweigh the Benefit of COVID-19 Vaccines

Sudden sensorineural hearing loss is an acute onset impairment of hearing that may lead to permanent hearing loss and tinnitus. The exact pathophysiological mechanisms are unknown, and many cases are idiopathic, although viral infection is 1 possible causative factor.¹ As a result, vaccination against viral infections may play a role in reducing the occurrence of sudden sensorineural hearing loss. However, little is known about sudden sensorineural hearing loss as a potential adverse event after immunization; existing reports of sudden sensorineural hearing loss occurring after vaccination are rare, and an association has not been established.² In this issue of JAMA Otolaryngology–Head & Neck Surgery, 2 articles investigate occurrences of sudden sensorineural hearing loss after COVID-19 vaccination.^3,4

Formeister et al³ present an analysis of sudden sensorineural hearing loss after COVID-19 vaccination using data from the Centers for Disease Control and Prevention Vaccine Adverse Events Reporting System (VAERS). The VAERS database is a passive surveillance system that accepts reports from health care professionals and patients. Although VAERS cannot establish causality between vaccines and adverse events, it is designed to detect unusual or unexpected safety signals to identify targets for more formal investigations of adverse events after immunization.⁵ The authors report that between December 14, 2020, and July 16, 2021, 185.4 million COVID-19 vaccine doses were administered in the US, and 555 VAERS reports met the definition for probable sudden sensorineural hearing loss. The estimated incidence range of sudden sensorineural hearing loss after vaccination was 0.6 to 28.0 cases per 100 000 people per year compared with the annual prepandemic incidence of idiopathic sudden sensorineural hearing loss of 11 to 77 cases per 100 000 people per year. The rate of reported sudden sensorineural hearing loss after COVID-19 vaccination was similar between the 3 vaccine types available in the US (BNT162b2 [Pfizer-BioNTech], mRNA-1273 [Moderna], and Ad26.Cov2.S [Janssen/Johnson & Johnson]). The authors also conducted a multi-institutional case-series analysis involving 21 patients; they did not identify any specific clinical or demographic risk factors among those experiencing sudden sensorineural hearing loss.

Yanir et al⁴ conducted a retrospective cohort study with a nonconcurrent comparison group using data from Clalit Health Services, which provides health care for more than one-half of the Israeli population (approximately 4.7 million people), between December 20, 2020, and May 31, 2021. In total, 2.6 million members of Clalit Health Services received a first dose of the BNT162b2 messenger RNA COVID-19 vaccine, and 2.4 million members received a second dose. Sudden sensorineural hearing loss after COVID-19 vaccination was diagnosed in 91 patients within 21 days after the first dose and 79 patients after the second dose. The incidence rate of sudden sensorineural hearing loss was 60.77 per 100 000 person-years after the first dose and 56.24 per 100 000 person-years after the second dose. In comparison, the incidence rates of sudden sensorineural hearing loss were 41.50 per 100 000 person-years in 2018 and 44.46 per 100 000 person-years in 2019. These rates corresponded to an age- and sex-weighted standardized incidence ratio of 1.35 (95% CI, 1.09-1.65) after the first dose and 1.23 (95% CI, 0.98-1.53) after the second dose compared with expected cases of sudden sensorineural hearing loss estimated from rates among the Clalit Health Services population in 2018 and 2019 during the same calendar period (January to May). The age- and sex-weighted attributable risk was 0.91 excess cases per 100 000 vaccinated individuals after the first dose and 0.61 excess cases per 100 000 vaccinated individuals after the second dose. Stratified by sex and age group, women 65 years or older had a higher standardized incidence ratio after the first dose (1.68; 95% CI, 1.15-2.37), and men aged 16 to 44 years had a high standardized incidence ratio after the second dose (2.45; 95% CI, 1.36-4.07).

Together, these 2 studies^3,4 involving almost 200 million COVID-19 vaccine doses suggest that further investigation of the potential association between COVID-19 vaccination and sudden sensorineural hearing loss may be warranted. Data from VAERS did not suggest that the incidence of sudden sensorineural hearing loss after vaccination exceeded the rate observed in the general US population,³ but data from Israel revealed a slightly higher risk of sudden sensorineural hearing loss after vaccination compared with expected rates.⁴ However, that study⁴ reported a minimal impact with regard to public health, with sudden sensorineural hearing loss occurring in fewer than 1 per 100 000 vaccinated individuals. Neither study identified clear demographic or clinical risk factors associated with sudden sensorineural hearing loss nor did they address important measurements regarding the severity and duration of hearing loss or the clinical outcomes after treatment.

These data must be weighed alongside the known risks of COVID-19, including COVID-19–associated sudden sensorineural hearing loss, and the many reported benefits of COVID-19 vaccination. The substantial impact of COVID-19 can be observed in the over 355 million cases and 5.5 million deaths reported globally since the start of the pandemic. Furthermore, it has been estimated that almost one-third of SARS-CoV-2 infections lead to long COVID or symptoms including chest pain, difficulty breathing, muscle pain, anxiety and depression, fatigue, and cognitive symptoms that can last longer than 3 months after diagnosis.⁶

COVID-19 vaccines are highly successful in preventing SARS-CoV-2 infection and in turn reducing the risk of transmitting the virus to others. Although the development of new variants of concern (ie, delta and omicron) have challenged the ability of the vaccines to prevent infection, existing vaccines appear to maintain substantial protection against severe illness. Most important, COVID-19 vaccines have been found to be beneficial at preventing severe COVID-19 illness, including hospitalizations and deaths. A systematic review and meta-analysis⁷ of vaccine effectiveness studies estimated that COVID-19 vaccines were associated with reductions in the risk of severe illness of almost 90% among people who had been fully vaccinated. It has been estimated that in the US alone, COVID-19 vaccinations may have prevented almost 140 000 deaths by May 2021.⁸

The many benefits of COVID-19 vaccines substantially outweigh the rare risks associated with vaccination. Targeted identification of sudden sensorineural hearing loss will aid in future investigations of this condition as an outcome of interest as well as assessments of potential adverse events after immunization and will aid in the timely recognition of sudden sensorineural hearing loss. Further research is needed to examine whether any demographic or clinical factors are associated with an increased risk of sudden sensorineural hearing loss after COVID-19 vaccination. Notably, if sudden sensorineural hearing loss is promptly diagnosed and treated early, hearing loss can be reversed or reduced. Additional research that addresses the severity and duration of hearing loss in cases temporally associated with vaccination and the outcomes after treatment is needed to understand the impact of any potential association between COVID-19 vaccines and sudden sensorineural hearing loss.

COVID-19 vaccines have undergone, and will continue to undergo, extensive safety monitoring by the Food and Drug Administration and the Centers for Disease Control and Prevention in the US and by other national and international monitoring bodies in other countries. In clinical trials and postmarket surveillance, COVID-19 vaccines have been found to be safe. Ongoing surveillance to detect rare adverse events after vaccination is important to ensuring the safety of these vaccines and engendering the public’s trust.

Corresponding Author: Angela K. Ulrich, PhD, MPH, Center for Infectious Disease Research and Policy, Division of Environmental Health Sciences, University of Minnesota, 420 Delaware St SE, Minneapolis, MN 55455 (ulric063@umn.edu).

Published Online: February 24, 2022. doi:10.1001/jamaoto.2021.4279

Conflict of Interest Disclosures: None reported.