Conclusion

Patients who have passed an episode of COVID-19 might test re-positive again, and furthermore, become ill seriously. A second positive PCR after discharge or negative PCR is not uncommon, and it is most likely due to disease reactivation or testing limitations, rather than another exogenous re-infection. Further prospective studies are needed to provide reliable epidemiologic data and reveal the mechanisms and risk factors for re-positives. Although anti-SARS-CoV-2 antibodies do not seem to prevent a second positive test, they might avert severe illness in re-positive patients.