JMIR Publications

ABSTRACT

Background:

Sudden sensorineural hearing loss (SSNHL) has recently been reported as a possible adverse effect of mRNA COVID-19 vaccination. However, no studies have described the clinical characteristics of post-vaccination SSNHL in terms of severity or duration nor examined the facilitating role of potential risk factors through a large and intensive post-marketing surveillance.

Objective:

The aim of this study is to evaluate the relationship between SSNHL and exposure to mRNA COVID-19 vaccines and estimate the reporting rates (RR) of mRNA-vaccines induced SSNHL.

Methods:

A national cross-sectional audiogram-based study was conducted using the French pharmacovigilance surveillance system for COVID-19 vaccines. All suspected cases of SSNHL after mRNA COVID-19 vaccination between January 2021 and February 2022 were examined based on a comprehensive audiological, and medical evaluation, including patient history, unilaterality or bilaterality of hearing loss, degree, and recovery after at least 3 months of follow-up. Using French administrative data, the RR of the two mRNA vaccine-induced SSNHL cases were also calculated according to the number of dose of each vaccine (tozinameran and elazomeran) administered during this period.

Results:

Results A total of 400 cases of SSNHL were reported for the two mRNA vaccines during this period, of which 171 (43%) well-documented cases could be retained: 142 SSNHL cases after Tozinameran vaccination (RR=1.45/1,000,000 injections; no difference between the first, second and booster injections; full recovery=37 cases; median interval between vaccine administration and symptom onset (i.e. delay onset) for delay onsets ≤21 days =4 days; median (range) age=51 (13-83) years; no sex effect), and 29 cases after Elasomeran vaccination (RR=1.67/1,000,000 injections; rank effect in favor of the first injection (p=0.036); full recovery=8 cases; median delay onset for delay onsets ≤21 days =8 days; median (range) age=47 (33-81) years; no sex effect). Autoimmune, cardiovascular, or audiovestibular risk factors were present in 50 (35%) Tozinameran cases and 9 (31%) Elasomeran cases. SSNHL was more often unilateral than bilateral (p<0.001 for Tozinameran) and its degree was mild to moderately severe on 71/118 (60%) audiogram tests. A positive rechallenge was identified in 5 cases for Tozinameran and 3 cases for Elasomeran immunisations.

Conclusions:

This study identified very rare cases of SSNHL for which the role of mRNA COVID-19 vaccination was supported, considering both diagnosis and onset time criteria. Given the benefits of vaccination and the possible occurrence of profound deafness and positive rechallenge, it is essential to thoroughly characterize any post-injection SSNHL cases, before providing individualized recommendations.