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. 2020 Nov;26(11):1556.e1-1556.e6.
doi: 10.1016/j.cmi.2020.07.008. Epub 2020 Jul 9.

Virus shedding dynamics in asymptomatic and mildly symptomatic patients infected with SARS-CoV-2

W Li  1 , Y-Y Su  2 , S-S Zhi  1 , J Huang  1 , C-L Zhuang  2 , W-Z Bai  1 , Y Wan  3 , X-R Meng  4 , L Zhang  3 , Y-B Zhou  4 , Y-Y Luo  4 , S-X Ge  5 , Y-K Chen  6 , Y Ma  7
Affiliations

Virus shedding dynamics in asymptomatic and mildly symptomatic patients infected with SARS-CoV-2

W Li et al. Clin Microbiol Infect. 2020 Nov.

Abstract

Objectives: Asymptomatic patients, together with those with mild symptoms of coronavirus disease 2019 (COVID-19), may play an important role in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. However, the dynamics of virus shedding during the various phases of the clinical course of COVID-19 remains unclear at this stage.

Methods: A total of 18 patients found to be positive for SARS-CoV-2 infection by real-time reverse transcription PCR (RT-PCR) assay and admitted to Chongqing University Central Hospital between 29 January and 5 February 2020 were enrolled into this study. Medical data, pulmonary computed tomographic (CT) scan images and RT-PCR results were periodically collected during the patients' hospital stay. All participants were actively followed up for 2 weeks after discharge.

Results: A total of nine (50%) asymptomatic patients and nine (50%) patients with mild symptoms of COVID-19 were identified at admission. Six patients (66.7%) who were asymptomatic at admission developed subjective symptoms during hospitalization and were recategorized as being presymptomatic. The median duration of virus shedding was 11.5, 28 and 31 days for presymptomatic, asymptomatic and mildly symptomatic patients, separately. Seven patients (38.9%) continued to shed virus after hospital discharge. During the convalescent phase, detectable antibodies to SARS-CoV-2 and RNA were simultaneously observed in five patients (27.8%).

Conclusions: Long-term virus shedding was documented in patients with mild symptoms and in asymptomatic patients. Specific antibody production to SARS-CoV-2 may not guarantee virus clearance after discharge. These observations should be considered when making decisions regarding clinical and public health, and when considering strategies for the prevention and control of SARS-CoV-2 infection.

Keywords: Antibodies; Asymptomatic infections; Convalescence; SARS-CoV-2; Virus shedding.

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Figures

Fig. 1
Fig. 1
Virus shedding dynamics in asymptomatic and mildly symptomatic COVID-19 patients. COVID-19, coronavirus disease 2019. For total antibody, "+" indicates cut-off index between 1 to 10, "++" cut-off index between 10 to 100, "+++" cut-off index 100 to 1000.
Fig. 2
Fig. 2
Serial cycle threshold (Ct) values of each test for each participant. Dotted red line indicates hospital admission; purple dotted line, hospital discharge; green triangle, throat swab; green circle, nasopharyngeal; green square, nasal swab; blue diamond, sputum; orange diamond, anal swab.
See this image and copyright information in PMC

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