The first follow-up RT-PCR
As per national protocol, RT-PCR testing was not performed upon discharge to confirm viral clearance. The first follow-up RT-PCR study was performed 30 days after the first positive RT-PCR result in each patient, which was after at least 14 days of being asymptomatic. Considering the short interval between the onset of the disease and the test, no recorded negative RT-PCR result at discharge, and the fact that the patients who tested positive were asymptomatic, we believe that the positive results show continued viral shedding rather than re-infection. The four patients who tested positive were not significantly different from others in terms of the severity of the initial illness, duration of the first admission, age, or underlying conditions to suggest a risk factor for a longer viral shedding period. Other studies have reported that up to 14% of recovering asymptomatic patients who tested negative upon discharge, re-test positive [29]. Other studies have reported patients who became symptomatic after a short symptom-free period. A 24-year-old health-worker became symptomatic and tested positive for SARS-CoV-2 within 52 days of an initial symptomatic diagnosis of COVID-19. Similar to our study, no confirmatory RT-PCR testing was performed at discharge. Serum antibodies were not detected at the beginning of the second symptomatic period, which can represent an incomplete immune response that left the infection temporarily dormant, only to be re-activated again; and although the patient was symptomatic and had occupational contact with infected patients during her symptom-free period, re-activation was considered more probable than re-infection [30]. Similar studies have reported a return of mild or even severe symptoms; but within a short time frame and without genetic analysis of the infective pathogens, they were reported to be cases of reactivation rather than re-infection [31-34].