Epidemiological characteristics of positive nucleic acid test results of the discharged re-positive cases infected with SARS-CoV-2 in Pudong New Area， Shanghai

ObjectiveTo obtain the epidemiological characteristics of re-positive cases infected with SARS-CoV-2 in Pudong New Area from March to July 2022, including clinical manifestations, duration of a negative nucleic acid conversion after tested for re-positive, and length of time from the discharge of the initial infection to the most recent re-positivity, so as to provide a scientific basis for the prevention and control of COVID-19.MethodsA questionnaire survey was conducted among the re-positive cases infected with SARS-CoV-2 after discharged from hospital/quarantine facility in Pudong New Area, and descriptive epidemiological methods were used for characteristics analysis.ResultsA total of 2 422 re-positive cases met the inclusive and exclusive criteria, with males accounting for 61.02%. The age distribution mainly fell between 18 and <60 years old, accounting for 62.39%. Clinical manifestations were predominantly asymptomatic (72.15%), followed by cough (12.03%) and sore throat (6.58%). Among the stratified randomized sample of 416 individuals, there were statistically significant differences in symptoms (χ²=262.667, P<0.001), clinical typing (χ²=12.996, P=0.001), and duration of a negative nucleic acid conversion (χ²=142.578, P<0.001) between the initial positive and re-positive instances. Besides, statistically significant differences in symptoms (χ²=13.696, P=0.016) and self-perception of the severity of re-infection (χ²=7.923, P=0.048) between the initial and re-positive cases were observed by different genders.ConclusionAmong re-positive cases, males experienced milder symptoms compared to females, and the self-perception of symptoms during re-positivity is milder than that in the initial positive infection. The length of time for negative nucleic acid conversion during the initial positive period is shorter than that during the re-positive period.