Viral Shedding with Recurrent SARS-CoV-2 Positive Cases in the Republic of Korea

Background: As of February 21, 2021, 86,992 cases of coronavirus disease 2019 (COVID-19) were confirmed in the Republic of Korea, with 1,557 deaths and 85,435 cases discharged from isolation. This study investigated the infectivity of individuals with COVID-19 who were retested and found to be severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA-positive after recovering from their primary illness. Methods: We investigated 295 individuals with recurrent SARS-CoV-2 positive results, and 836 of their close contacts. We attempted virus isolation in 108 individuals with recurrent SARS-CoV-2 positivity using cell culture and confirmed the presence of neutralizing antibodies by means of serological tests. Findings: The average age was 45·2 years (range, 1–95 years) and 64% were female. At the time of retesting, 55·6% were asymptomatic, and symptoms included cough (18·0%), expectoration (11·2%), sore throat (10·8%), and fever (9·2%). The reasons for retesting were screening (46%), persistent symptoms (37·6%), and new contact with a confirmed COVID-19 case (9·5%). Virus isolation was attempted in 108 individuals with recurrent SARS-CoV-2 positivity, and all tested negative. Three new cases were identified among household contacts based on SARS-CoV-2 polymerase chain reaction testing. Two of the three new cases had had contact with the index patient during their primary illness, and all three had antibody evidence of past infection. Interpretation: There was no laboratory evidence of viral shedding and no epidemiological evidence of transmission among individuals with recurrent positivity. Funding Statement: This study was funded by the Korea Disease Control and Prevention Agency (No. 4800-4837-301). Declaration of Interests: The authors declare no conflicts of interest related to the study. Ethics Approval Statement: The study was approved by the KDCA Institutional Review Board (2020-03-01-P-A). The board waived the requirement for written informed consent.