Objectives: The aim of this study was to elucidate patterns of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) clearance in the natural course of asymptomatic coronavirus disease 2019 (COVID-19). Methods: Consecutive patients with non-severe COVID-19 were included retrospectively. Asymptomatic patients with a normal body temperature and no evidence of pneumonia throughout the disease course were assigned to the asymptomatic group. The reverse transcription PCR (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 RT-PCR assay results within a 24-h interval. Rebound of the cycle threshold (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 identified (median age 42.5 years (interquartile range (IQR) 25.0–55.0 years), 35.6% male), 68 (17.2%) were assigned to the asymptomatic group and 328 (82.8%) to the symptomatic group. The time until negative conversion was significantly shorter in the asymptomatic group than in the symptomatic group: median 14.5 days (IQR 11.0–21.0 days) and 18.0 days (IQR 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.
Bibliographical noteFunding Information:
The authors thank Young-Jin Song, MD, PhD, the director of Chungju Medical Center for his help with data collection, Nak-Hoon Son, PhD, the biostatistician of Yongin Severance Hospital, Yonsei University College of Medicine for his statistical analysis, and Christina Ignat, PhD for English language editing.
All Science Journal Classification (ASJC) codes
- Microbiology (medical)
- Infectious Diseases