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February 24, 2022
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Benefits of COVID-19 vaccine 'outweigh its potential association' with sudden hearing loss

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A recent study conducted in Israel identified a potential link between COVID-19 vaccination and sudden sensorineural hearing loss, while a similar study conducted in the U.S. found no significant association.

The findings of both studies were published in JAMA Otolaryngology-Head and Neck Surgery.

Among more than 2 million Israeli adults, the 21-day cumulative incidence of sudden hearing loss per 100,000 people after a COVID-19 vaccination.
Yanir Y, et al. JAMA Otolaryngol Head Neck Surg. 2022;doi:10.1001/jamaoto.2021.4278. 

“I want to emphasize that this is not something that should encourage people not to get vaccinated,” Yoav Yanir, MD, a physician in the department of otolaryngology-head and neck surgery at Lady Davis Carmel Medical Center in Israel, told Healio. “We want to raise awareness of sudden sensorineural hearing loss (SSNHL) and we want physicians to know that there is a connection, but the numbers are very small.”

Pfizer vaccine and SSNHL

In a retrospective, population-based cohort study in Israel, Yanir and colleagues assessed the association between the Pfizer-BioNTech COVID-19 vaccine and SSNHL in individuals aged 16 years or older who received one or two doses of the vaccine. Yanir and colleagues compared cases of SSNHL that occurred within 21 days after each vaccine dose to cases that occurred in the general population in 2018 and 2019 to determine standardized incidence ratios (SIR), attributable risk fractions and attributable risk.

Overall, 2,602,557 individuals received their first dose of the Pfizer COVID-19 vaccine between Dec. 20, 2020, and April 30, 2021. Their mean age was 46.8 years and 51.5% were women. Of these individuals, 2,441,719 received their second vaccine dose between Jan. 10, 2021, and April 30, 2021.

Yanir and colleagues reported that SSNHL occurred within 21 days in 91 patients after the first vaccine dose, amounting to a 21-day cumulative incidence of 3.5 per 100,000 individuals. SSNHL also occurred in 79 patients after the second vaccine dose, amounting to a 21-day cumulative incidence of 3.24 per 100,000 individuals.

During the study period, the researchers observed an increase in the incidence of SSNHL. Specifically, the incidence rate of SSNHL was 60.77 (95% CI, 48.29-73.26) per 100,000 person-years after the first vaccine dose and 56.24 (95% CI, 43.83-68.64) per 100,000 person-years after the second vaccine dose, according to the researchers. Previous corresponding incidence rates of SSNHL in Israel were 41.5 (95% CI, 37.98-45.01) per 100,000 person-years in 2018 and 44.46 (95% CI, 40.85-48.07) per 100,000 person-years in 2019.

When accounting for the incidence rate of the general population in 2018, the incidence of SSNHL among participants after the first vaccine dose tended to be higher among women and girls aged 16 to 44 years (SIR = 1.92; 95% CI, 0.98-3.43) and among adults aged 65 years or older (SIR = 1.68; 95% CI, 1.15-2.37). After the second vaccine dose, the incidence was higher in men and boys aged 16 to 44 years (SIR = 2.45; 95% CI, 1.36-4.07).

Yanir and colleagues reported that the overall age- and sex-weighted SIR was 1.35 (95% CI, 1.09-1.53) after the first vaccine dose and 1.23 (95% CI, 0.98- 1.53) after the second dose, with a very small effect size.

“Considering these findings along with the good prognosis for patients with SSNHL, we suggest that the benefits of the [Pfizer] COVID-19 vaccine outweigh its potential association with SSNHL,” the researchers wrote.

Pfizer, Moderna, J&J vaccine and SSNHL

In a separate cross-sectional, population-based study conducted in the U.S., Eric J. Formeister, MD, MS, a fellow in otology and neurotology at Johns Hopkins Medicine, and colleagues analyzed data on probable cases of SSNHL that were reported to the CDC’s Vaccine Adverse Events Reporting System (VAERS) from Dec. 14, 2020, to July 16, 2021. Physicians and patients are able to report cases through VAERS, which sometimes leads to duplicate or false instances of SSNHL, Formeister told Healio.

Eric Formeister
Eric J. Formeister

The researchers also analyzed a case series of 21 patients at two tertiary care centers and one community practice who developed SSNHL within 3 weeks of a Pfizer, Moderna or Johnson & Johnson COVID-19 vaccination.

Overall, Formeister and colleagues identified 555 incidents of probable SSNHL in VAERS. The mean age of the individuals was 54 years and 55% were women. Most probable cases of SSNHL involved the Pfizer vaccine (55%), followed by the Moderna vaccine (40%) and the Johnson & Johnson vaccine (5%). The mean time to onset of symptoms was 6 days.

These 555 cases represented an incidence estimate of 0.6 to 28 cases of SSNHL per 100,000 people per year. The rate of incident reports of SSNHL was similar across the vaccine manufacturers: 0.16 cases per 100,000 doses for the Pfizer and Moderna vaccines, and 0.22 cases per 100000 doses for the Johnson & Johnson vaccine.

Among the 14 patients in the case series with posttreatment audiometric data, 57.1% experienced an improvement after treatment, according to the researchers.

“We can’t say for certain that there is an association [between the COVID-19 vaccinations and SSNHL], and we can’t say for certain that there isn’t an association,” Formeister said.

The lack of a robust reporting system hindered the investigation, he added.

Risk vs. benefit of COVID-19 vaccines

Angela K. Ulrich, PhD, MPH, an assistant professor in the Center for Infectious Disease Research and Policy at the University of Minnesota School of Public Health, and colleagues responded to the findings of both studies in a related editorial.

Together, the studies represented almost 200 million COVID-19 vaccine doses, according to the authors. The findings indicate the need for further investigation into the association between COVID-19 vaccination and SSNHL, as both studies were lacking key data.

“The many benefits of COVID-19 vaccines substantially outweigh the rare risks associated with vaccination,” Ulrich and colleagues wrote. “Targeted identification of sudden sensorineural hearing loss will aid in future investigations of this condition as an outcome of interest as well as assessments of potential adverse events after immunization and will aid in the timely recognition of sudden sensorineural hearing loss.”

They added that hearing loss can be reduced or reversed if SSNHL is diagnosed early, underscoring the importance of ongoing surveillance and reporting of rare adverse events like SSNHL after vaccination.

References:

Formeister EJ, et al. JAMA Otolaryngol Head Neck Surg. 2022;doi:10.1001/jamaoto.2021.4414.

Ulrich AK, et al. JAMA Otolaryngol Head Neck Surg. 2022;doi:10.1001/jamaoto.2021.4279.

Yanir Y, et al. JAMA Otolaryngol Head Neck Surg. 2022;doi:10.1001/jamaoto.2021.4278.