ABSTRACT
Some patients retested positive for SARS-CoV-2 following negative testing results and discharge. However, the potential risk factors associated with redetectable positive test results in a large sample of patients who recovered from COVID-19 have not been well estimated. A total of 745 discharged COVID-19 patients were enrolled between January 30, 2020, and September 9, 2020, in Guangzhou, China. Data on the clinical characteristics, comorbidities, drug therapy, RT-PCR testing, and contact modes to close contacts were collected. Patients who tested positive for SARS-CoV-2 after discharge (positive retest patients) were confirmed by guidelines issued by China. The repositive rate in different settings was calculated. Among 745 discharged patients, 157 (21.1%; 95% CI, 18.2% to 24.0%) retested positive, of which 55 (35.0%) were asymptomatic, 15 (9.6%) had mild symptoms, 83 (52.9%) had moderate symptoms and 4 (2.6%) had severe symptoms at the first admission. The median time from discharge to repositivity was 8.0 days (IQR, 8.0 to 14.0 days). Most positive retest patients were without clinical symptoms, and lymphocyte cell counts were higher than before being discharged. The likelihood of repositive testing for SARS-CoV-2 RNA was significantly higher among patients who were younger age (OR, 3.88; 95% CI, 1.74 to 8.66, 0 to 17 years old), had asymptomatic severity (OR, 4.36; 95% CI, 1.47 to 12.95) and did not have clinical symptoms (OR, 1.89; 95% CI, 1.32 to 2.70, without fever). We found that the positive retest rate of COVID-19 was relatively high, and these patients tested positive again with a median of 8.0 to 14.0 days after discharge. Positive retest results were mainly observed in young patients without severe clinical symptoms. These findings suggest that a significant proportion of patients could carry viral fragments for a long time, and effective management, such as a prolonged quarantine phase for discharged patients, is necessary.