Clinical factors associated with viral shedding time of SARS-CoV-2 Omicron variant in Japan.

The Omicron variant of severe acute respiratory syndrome coronavirus 2 exhibits increased infectivity compared with all prior variants, and the timing of quarantine release should be carefully considered. However, to date, only two Chinese studies have analyzed the association between the viral shedding time (VST) and risk factors among patients infected with the Omicron variant. These studies included only limited numbers of severe cases and no analysis of underlying diseases and immunosuppressive drug use. Therefore, the current study aimed to analyze them in Japan. This retrospective observational study was conducted at the University of Occupational and Environmental Health, Japan, from January 2022 to October 2022 and included 87 hospitalized patients and 305 healthcare workers (HCWs) with coronavirus 2019 (COVID-19). In comparison with HCWs, hospitalized patients were significantly older and had a higher proportion of severe COVID-19 cases and significantly longer VST. A simple regression analysis showed that severe, current, or ex-smoking status, cardiovascular diseases, chronic kidney disease, and use of corticosteroids for underlying diseases were significantly correlated with a longer VST. Moreover, multiple linear regression analysis revealed that cardiovascular diseases, chronic kidney disease, and corticosteroid use were significantly associated with a longer VST. Therefore, COVID-19 patients with these underlying diseases may require a longer isolation period and the timing of quarantine release should be carefully considered.