COVID-19 vaccines don´t rise risk of sudden hearing loss

COVID-19 vaccines do not increase the risk of sudden hearing loss, according to a recent epidemiological study by experts of the Finnish Institute of Health and Welfare (THL) and Tampere University Hospital (Tays).

“We have used a register study to monitor all coronavirus vaccine preparations in use in Finland and examined cases of sudden hearing loss 54 days after each vaccination. Sudden hearing loss was not more frequent than normal after the COVID-19 vaccinations. Being infected by COVID-19 also did not appear to increase the risk of sudden hearing loss”, said Petteri Hovi, Senior Researcher at THL.

The study does not support results of an earlier Israeli study of a connection between COVID-19 vaccinations and sudden hearing loss.

A possible connection between coronavirus vaccines and sudden hearing loss raised international debate when an Israeli study reported a 40-percent increase in hearing loss within 21 days of getting the BioNTech/Pfizer's mRNA vaccine (ComirnatyR).

“The result of the Israeli study can be explained by differences in the control group, or by changes in treatment practices or seeking treatment in the course of time”, Hovi said.

Age and gender were considered in the THL and Tays study, as they were in the Israeli study. Prior illnesses and differences in the onset of sudden hearing loss at different parts of the day and at different phases of the epidemic were also considered.

Diagnoses of sudden hearing lost declined considerably right at the start of the COVID-19 epidemic. The decline in seeking medical treatment during the epidemic is seen as a possible reason for this.

The diagnosis rate for sudden hearing loss returned to the normal level at about the time when COVID-19 vaccinations began in late 2020 and early 2021.

Sudden hearing loss affected 1216 people between January 2019 and March 2020 and the prevalence in the population was 18.7 cases per 100,000 for each year that monitoring took place. In the coronavirus epidemic, and especially in its early stages, there was much monthly variation in the incidence of sudden hearing loss. It varied between 11-27 cases per 100,000 in the years that were monitored independent of the vaccinations.

Coronavirus vaccines are generally effective and safe, but they can also be linked with some serious and rare side effects. Sudden hearing loss can be a serious illness, but for 40-60 percent of treated cases, hearing returns to normal within a few weeks.

Based on the study by THL and Tays, it is unlikely that sudden hearing loss would be one of the side effects of COVID-19 vaccines.

The risk/benefit ratio of coronavirus vaccinations and the monitoring of the side-effects should be actively continued.

The study was conducted between 1 January 2019 and 12 April 2022, and those monitored included all persons who resided in Finland at the time. A total of 11.9 million vaccinations against coronavirus were administered at the time.