METHODS: This case-control study analysed samples from adults aged 18 years and older who visited the otorhinolaryngology department in 32 government hospitals in Malaysia for pure tone audiometry(PTA) between January 25, 2020 and June 30, 2022. Cases comprised patients diagnosed with ISSNHL, while controls consisted of individuals with normal PTA assessments presenting for other otorhinolaryngology-related symptoms during the same period. Patients with known causes of hearing loss were excluded. Cases and controls were matched in a 1:5 ratio based on age (± 5 years) and index date (± 10 days). The study investigated the association between ISSNHL and both COVID-19 vaccination and COVID-19 infection using conditional logistic regression, with statistical significance set at P groups had similar proportions of COVID-19 vaccination [90 (48.1%) vs 415 (44.5%), P = 0.377]. Individuals who tested positive for COVID-19 had a significantly higher likelihood of developing ISSNHL compared to those without COVID-19 infection at the time of diagnosis (aOR:2.49; 95% CI:1.176 - 5.260; P = 0.017). However, there was no statistically significant association between COVID-19 vaccination and ISSNHL.