Spontaneous adverse reaction reports of sudden hearing loss have been observed, and a population-based cohort study conducted in Israel showed an increase in the incidence of sudden sensorineural hearing loss (SSNHL) following vaccination with messenger RNA COVID-19 vaccine BNT162b2 (Pfizer-BioNTech).

However, in this setting, the possibility of confounding remained.

We assess a potential association between COVID-19 vaccinations and SSNHL.

This register-based country-wide retrospective cohort study of 5.5 million Finnish residents was conducted from January 1, 2019, to April 20, 2022, and included all individuals who were identified from the population information system who were alive or born during the study period except individuals who had SSNHL during 2015 to 2018 according to specialized care derived diagnosis codes for SSNHL (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision [ICD-10] code H91.2) as a primary or secondary diagnosis.