Formeister, et al. (2021) say that many vaccine-related adverse events are associated with otolaryngologic manifestations. In particular, the incidence of sudden sensorineural hearing loss (SSNHL) was examined after influenza vaccination in a large-scale study that demonstrated no association between vaccination and the rate of SSNHL. Anecdotal reports are rapidly emerging from the otolaryngology community of SSNHL occurring after inoculation by SARS-CoV-2 vaccines that are currently in use in the U.S. under Food and Drug Administration Emergency Use Authorizations.

Recognizing the important public health implications of any association between COVID-19 vaccination and SSNHL, and motivated by patients who presented to their practice (Johns Hopkins University; Baltimore, Maryland) with audiometrically confirmed unilateral SSNHL that occurred within 24 hours of COVID-19 vaccination, the researcher sought to (1) estimate the national incidence of SSNHL after COVID-19 vaccination using data from the Vaccine Adverse Events Reporting System (VAERS) maintained by the Centers for Disease Control and Prevention (CDC) and (2) compare this with the expected incidence of SSNHL in the wider population.

The CDC VAERS is a national repository of incident reports associated with adverse reactions that occur after any vaccination. Any individual may submit a report, and all reports are publicly available. This database was queried for adverse events in which sudden hearing loss, deafness, deafness unilateral, deafness neurosensory, and hypoacusis were listed as an adverse event from vaccinations administered between December 14, 2020, and March 2, 2021, which yielded 147 reports after deduplication. The narrative and laboratory results section of each report were reviewed. A subset of all incidents found to have a temporal association (onset of hearing loss occurred within three weeks of vaccination) and high credibility of reporting (eg, reported by a healthcare clinician with documentation of audiologic findings or steroid treatment) were classified as most likely (n = 40; 25 women [63%]). The researchers then estimated the incidence of SSNHL that occurred after vaccination on an annualized basis, performed a sensitivity analysis of this estimate, and compared our findings with known incidence of SSNHL in the wider population.

Between December 14, 2020, and March 2, 2021, 86 553 330 SARS-CoV-2 vaccine doses were administered in the US. Because VAERS reports are unverified, susceptible to underreporting bias, and the number of unique individuals within the vaccine cohort is not known exactly, the researchers performed a sensitivity analysis and estimated a minimum and maximum incidence by tuning these assumptions. The results of these incidence estimates compared with the known population incidence of SSNHL demonstrate that the incidence of SSNHL occurring after COVID-19 vaccination does not exceed that of the general population, and may be lower.

Reference: Formeister EJ, et al. Preliminary Analysis of Association Between COVID-19 Vaccination and Sudden Hearing Loss Using US Centers for Disease Control and Prevention Vaccine Adverse Events Reporting System Data. JAMA Otolaryngol Head Neck Surg. Published online May 20, 2021. doi:10.1001/jamaoto.2021.0869