Changes in Otorhinolaryngologic Disease Incidences before and during the COVID-19 Pandemic in Korea

This study aimed to investigate the change in the incidence and variance of otorhinolaryngologic diseases during the coronavirus disease 19 (COVID-19) pandemic. The entire Korean population (~50 million) was evaluated for the monthly incidence of 11 common otorhinolaryngologic diseases of upper respiratory infection (URI), influenza, acute tonsillitis, peritonsillar abscess, retropharyngeal and parapharyngeal abscess, acute laryngitis and bronchitis, stomatitis and related lesions, acute sinusitis, rhinitis, otitis media, and dizziness from January 2018 through March 2021 using the International Classification of Disease (ICD)-10 codes with the data of the Korea National Health Insurance Service. The differences in the mean incidence of 11 common otorhinolaryngologic diseases before and during COVID-19 were compared using the Mann-Whitney U test. The differences in the variance of incidence before and during COVID-19 were compared using Levene's test. The incidence of all 11 otorhinolaryngologic diseases was lower during COVID-19 than before COVID-19 (all p < 0.05). The variations in disease incidence by season were lower during COVID-19 than before COVID-19 for infectious diseases, including URI, influenza, acute tonsillitis, peritonsillar abscess, retropharyngeal and parapharyngeal abscess, acute laryngitis and bronchitis, acute sinusitis, and otitis media (all p < 0.05), while it was not in noninfectious diseases, including stomatitis, rhinitis, and dizziness. As expected, the incidences of all otorhinolalryngolgic diseases were decreased. Additionally, we found that seasonal variations in infectious diseases disappeared during the COVID-19 pandemic, while noninfectious diseases did not.