Early Detection of Hearing Impairment Signals Post-mRNA COVID-19 Vaccination: A Disproportionality Analysis Study on French Pharmacovigilance Database

Introduction Improving adverse events following immunisation (AEFI) detection is vital for vaccine safety surveillance, as an early safety signal can help minimize risks. In February 2022, the World Health Organization reported a preliminary signal on sudden sensorineural hearing loss (SSNHL) following coronavirus disease 2019 (COVID-19) vaccination, 54 million persons in France received at least one dose, covering 78.8% of the population within a year. Objective The primary objective of this study was to identify a method of disproportionality analysis capable to detect a safety signal for hearing impairment (HI) as early as possible during the initial phases of the COVID-19 vaccination campaign. Secondly, we described all cases of SSNHL reported during vaccine booster campaigns in France. Methods Data from January 2011 to February 2022 were extracted from the French pharmacovigilance database. Cases were all spontaneous reports of AEFI for elasomeran and tozinameran, while non-cases were AEFI reported for other vaccines. Disproportionality analysis for HI was performed monthly during 2021, to estimate a reporting odds ratio (ROR). Four different methods were used for ROR estimation. Furthermore, we reviewed cases of SSNHL following messenger RNA COVID-19 vaccinations reported during booster campaigns, from 2 February 2022 to 1 March 2023, based on a comprehensive medical evaluation. Results Using a standard methodology, we identified a signal on 31 July 2021 (ROR 1.50, 95% confidence interval [CI] [1.06–2.18]). Multivariate analysis adjusted for sex, age, ototoxic drugs and excluding reference reports of common AEFI for vaccines allowed us to detect the HI signal as early as 31 March 2021 (ROR 2.67, 95% CI [1.36–5.57]). The SSNHL reporting rate was estimated to be 0.83/1,000,000 doses for tozinameran and 4.3/1,000,000 for elasomeran during the booster campaigns. Conclusion Using a well-structured disproportionality analysis could have enhanced early detection of safety signals and contribute to risk minimizing measures. According to descriptive data, HI following mRNA COVID-19 vaccines remains rare.