Epidemiology and Clinical Findings of Recurrence for SARS-CoV-2 RNA in Discharged COVID-19 Cases: An Observational Study

Background: Recurrence of positive SARS-CoV-2 RNA in discharged COVID-19 patients attracts the public’s concern. It remained unknown whether this phenomenon means relapse of disease or transmissible, which is essential to the management of discharged COVID-19 patients. Methods: A multi-center, retrospective, observational study was conducted on 32 designated hospitals for COVID-19 in Guangdong Province. All COVID-19 discharged patients from January 14th to March 10th, 2020 were enrolled in this study, and were followed up for 14 days with testing of SARS-CoV-2 nucleic RNA, observation of clinical symptoms, chest CT scan and laboratory tests. Clinical symptoms and RNA test also were carried out in their close contacts. Findings: Of 1,282 discharged patients enrolled in this study, 155(12.1%)were tested positive of SARS-CoV-2 RNA during 14 days’ follow-up. The median time of recurrence of SARS-CoV-2 RNA was 7 days (IQR4-9). Compared to negative group, the patients from re-positive group were a younger (35yr vs 45yr mean,p<0.001) and had a higher proportion of moderate cases (95.5% vs 84.7%, p<0.001). None of the re-positive patients showed symptoms, abnormal in peripheral white blood cell and lymphocyte accounts during the second admission to hospital. 74.2% further improved on chest CT scan images and 20.0% had no remarkable changes. The median time of all re-positive patients turned viral RNA negative was 8.0 days (IQR4-14). Only 25.2% re-positive patients accepted antiviral therapy at their second admission. None of close contacts (n=202) derived from re-positive patients (n=67) developed to COVID-19 patients. Interpretation: The fact that none of the re-positive patients relapse or become transmissible suggest low risk of onward transmission of these patients. However, close monitoring is still needed since limit knowledge obtained regarding to this novel coronavirus.Funding Statement: This study is supported by Special Project on Emergency Response to Control of Novel Coronavirus Infection of Guangdong Province (NO. 163-2018-XMZC-0001-170-0108) and National Natural Science Foundation of China (NO. 81701875). Declaration of Interests: All authors declare no competing interests.Ethics Approval Statement: This study was authorized by the Guangdong Provincial Health Commission, and it was approved by the Ethics Committee of the Guangdong Provincial People's Hospital (No. GDREC2020028H).