Reactivation of SARS-CoV-2 infection following recovery from COVID-19

Introduction: Many individuals test positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA after recovering from the coronavirus disease (COVID-19), but the incidence of reactivation is unknown. We, therefore, estimated the incidence of reactivation among individuals who had recovered from COVID-19 and determined its predictors. Methods: In this retrospective cohort study, patients with COVID-19 were followed up for at least 14 days after two consecutive negative SARS-CoV-2 polymerase chain reaction test results obtained ≥24 h apart, and the frequency of SARS-CoV-2 reactivation was assessed. Results: Of the 109 patients, 29 (27%) experienced reactivation, and seven (24%) of these were symptomatic. The mean period for the real-time PCR tests for SARS-CoV-2 from negative to positive results was 17 days. Compared with patients without reactivation, those with reactivation were significantly younger and more likely to have a lymphocyte count of <1500/μL (odds ratio [OR]: 0.34, 95% confidence interval [CI]: 0.12–0.94) and two or fewer symptoms (OR: 0.20, 95% CI: 0.07–0.55) during the initial episode. Conclusion: Risk-stratified surveillance should be conducted among patients who have recovered from COVID-19.