Patterns of Viral Clearance in the Natural Course of Asymptomatic Coronavirus Disease 2019 (COVID-19): Comparison with Symptomatic Nonsevere COVID-19.

Abstract Objectives The aim of the study was to elucidate patterns of SARS-CoV-2 clearance in the natural course of asymptomatic coronavirus disease 2019 (COVID-19). Methods Consecutive patients with nonsevere COVID-19 were retrospectively included. Asymptomatic patients with normal body temperature and no evidence of pneumonia throughout the disease course were classified in the asymptomatic group. The reverse transcription polymerase chain reaction (RT-PCR) assay was repeated every two to five days after the first follow-up RT-PCR assay. Negative conversion was defined as two consecutive negative results of RT-PCR assays within a 24-h interval. Rebound of threshold cycle (Ct) value was defined as negative from the single RT-PCR assay and positive from the following assay. Results Among a total of 396 patients [age, 42.5 (25.0–55.0) years; males, 35.6%], 68 (17.2%) and 328 (82.8%) patients were in the asymptomatic and symptomatic groups, respectively. The time until negative conversion was significantly shorter in the asymptomatic group than in the symptomatic group [14.5 (11.0–21.0) days and 18.0 (15.0–22.0) days, respectively; p = 0.001]. Rebound of Ct values was observed in 78 patients (19.7%). Conclusions Time until negative conversion is shorter in asymptomatic COVID-19 than in symptomatic COVID-19. Rebound of Ct values is not uncommon.