Patterns of viral clearance in the natural course of asymptomatic COVID-19: Comparison with symptomatic non-severe COVID-19

Jae Sun Uhm, Jin Young Ahn, Jong Hoon Hyun, Yujin Sohn, Jung Ho Kim, Su Jin Jeong, Nam Su Ku, Jun Yong Choi, Yu Kyung Park, Ho sung Yi, Sung Kyu Park, Bong Ok Kim, Hyewon Kim, Jinwoo Choi, Seung mo Kang, Yeong Ho Choi, Hae Kyoung Yoon, Sunkyung Jung, Hyeong Nyeon Kim, Joon Sup YeomYoon Soo Park

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25 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)279-285
Number of pages7
JournalInternational Journal of Infectious Diseases
Publication statusPublished - 2020 Oct

Bibliographical note

Publisher Copyright:
© 2020 The Author(s)

All Science Journal Classification (ASJC) codes

  • Microbiology (medical)
  • Infectious Diseases


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