Epidemiological characteristics of recovered COVID-19 cases with re-positive nucleic acid in Pudong New Area of Shanghai from May to June 2022

ObjectiveTo understand the epidemiological characteristics of recovered COVID-19 cases with re-positive nucleic acid in Pudong New Area of Shanghai, and to provide a reference for the prevention and control of COVID-19.MethodsA three-month health follow-up and nucleic acid testing were conducted on 339 COVID-19 cases cured and discharged between May 20 and June 20, 2022, in Pudong New Area, Shanghai, to analyze their epidemiological characteristics.ResultsAmong the 339 follow-up cases, 75 cases experienced re-positive nucleic acid results, with a recurrence rate of 22.12%. Factors such as gender, age group, occupation, presence of heart disease, hypertension, and full vaccination status had no effect on the re-positive results. Being diagnosed as a confirmed case during the first presence of infection, having diabetes, and a hospitalization period of ≤7 days were related factors for recurrence. The median interval between discharge and re-positive nucleic acid results was 26 days. The close contacts of the re-positive cases did not contract COVID-19 after the isolation and observation period.ConclusionThere is a possibility of re-positive nucleic acid results after COVID-19 recovery and discharge. Cases initially diagnosed as confirmed cases and those with a hospitalization period of no more than 7 days have a high rate of re-positivity. No secondary transmission is observed from the re-positive cases.