Proposed features for distinguishing SARS-CoV-2 reinfection from prolonged SARS-CoV-2 viral shedding
| SARS-CoV-2 reinfection | Prolonged SARS-CoV-2 viral shedding | |
| Sequencing | Confirmed RNA sequencing with evidence of distinct SARS-CoV-2 viral strains at distinct episodes would provide a definitive diagnosis of SARS-CoV-2 reinfection | RNA sequencing showing the same SARS-CoV-2 viral strains at distinct periods could suggest prolonged SARS-CoV-2 viral shedding rather than reinfection; unless clinical suspicion is high for SARS-CoV-2 reinfection, further evaluation would be needed to assess if the patient has been reinfected with the same SARS-CoV-2 strain |
| Cycle threshold (Ct) values | Variability in SARS-CoV-2 Ct detection has been documented in cases of SARS-CoV-2 reinfection, with some cases with increased or decreased Ct values on reinfection episode (with Ct varying from 16.6 to 36.85)8 | Likely to have high Ct values suggesting low level viral shedding; however, low Ct values may be observed in immunocompromised patients who have decreased ability to clear the virus |
| Viral culture | Likely to be positive | Could be positive or negative (latter representing non-viable virus detected via SARS-CoV-2 PCR tests) |
| Timing of repeat positive testing | Variable; time between positive SARS-CoV-2 RNA PCR in documented cases of SARS-CoV-2 reinfection ranges from 48 to 142 days8 | Variable |
| Antibody testing in blood | Could be positive or negative* | Could be positive or negative |
| Host characteristics | Variable; the majority of documented cases of SARS-CoV-2 infections noted in immunocompetent hosts (with the exception of one patient taking inhaled corticosteroids)8 | Variable; notably, immunocompromised hosts are more likely to have prolonged episodes of SARS-CoV-2 viral shedding |
| Symptomatic vs. asymptomatic presentation | Variable symptoms; may have milder (including asymptomatic presentations) or worsening symptoms as noted in prior cases of SARS-CoV-2 reinfection8 | Predicted to have asymptomatic presentation if due to prolonged SARS-CoV-2 viral shedding |
*SARS-CoV-2 re-infections may occur more commonly in individuals with waning immunity after their first SARS-CoV-2 infection.