Researchers from the Korean Otological Society (KOS) have found that vaccination against Covid-19 can cause sudden sensorineural hearing loss (SSNHL).
KOS members announced the study results during the society’s spring conference held in Seoul over the weekend. SSNHL is an urgent symptom that greatly affects the quality of life. Although the cause is still a mystery, some researchers have hinted at the possibility of viruses or vascular compression affecting the onset of symptoms.
The research team, led by KOS President Koo Ja-won, conducted the study to check whether SSNHL can develop after the Covid-19 vaccination. The team enrolled 207 patients at 26 Korean hospitals and studied them from Feb. 2021 to Jan 2022.
As a result, the researchers found that subjects developed SSNHL within 31 days of vaccination.
The analysis showed that out of the 193 cases of SSNHL, the vaccine with the highest correlation with SSNHL was Pfizer’s vaccine with 127 cases, followed by AstraZeneca (37), Moderna (28), and Janssen (one).
When looking at the incidence of hearing loss by vaccination period, President Koo’s team discovered that patients reported hearing loss the most after their second jab with 41.7 percent, followed by the first dose (39.1 percent) and third dose (21 percent).
The average time to onset of sudden hearing loss symptoms was 9.2 days after injection, and most of the patients received treatment with steroids.
However, the KOS stopped short of implying a direct association between the vaccine and SSNHL as symptoms usually improved when treated immediately.
Instead, the otological society stressed that the study means that it carried out the study to remind people of the need for immediate examination and treatment in the case of SSNHL.
“SSNHL can appear in the course of receiving any vaccination, including the Covid-19 vaccine,” KOS medical director Park Hong-joo said. “The problem is that it may occur after a day or two for each patient, and the onset time is different, complicating the causal relationship confirmation.”
As there were so many inoculations during the Covid-19 pandemic, the study observed the change in the incidence of SSNHL during the vaccination period if the patient showed adverse reactions after vaccination, Park added.
Park stressed that the KOS confirmed a tendency to develop SSNHL in the early stage of vaccination due to the study.
“However, as symptoms occurred in some and not all patients, we only see a slight tendency,” Park said. “Since SSNHL has a good prognosis if intensively treated early, the study is more meaningful. It informed the possibility of new symptoms of SSNHL and countermeasures.”
Meanwhile, KOS members published a study on wearing a mask, which has been routine since 2019, in the hearing loss patient group and the normal hearing group.
The researchers also found that wearing a mask significantly impaired conversation in the hearing loss patient group.