Table 1 Interpretation matrix to assess suspected reinfections
S/N | Result from Repeated PCR | Serology Result | Interpretation | Clinical actions to be taken | Action to be taken by Microbiology |
|---|---|---|---|---|---|
1 | Ct ≥ 30 or Repeat negative | Positive | Unlikely reinfection, likely persistent shedder | Consider discharging If there are any residual concerns, follow up in clinic with intervening medical leave and consider repeating tests | Nil |
2 | Ct ≥ 30 or Repeat negative | Negative | Unlikely reinfection, likely persistent shedder Possible waned immunity | Consider discharging. If there are any residual concerns, follow up in clinic with intervening medical leave and repeating tests | Nil |
3 | Ct < 30 or current Ct value less than Ct from last PCR test (if the same assay and sample type used) | Low quantitative serology titre (Anti-S) | Possible Reinfection, repeat serology (~ 2 weeks later) | If specimen error has been ruled out, manage as per protocols for suspect/confirmed case | Repeat PCR Consider viral cultures and sequencing Consider multiplex respiratory virus PCR to evaluate for other infections if symptomatic |
4 | Ct < 30 consistently on repeated testing or current Ct value significantly less than Ct from last PCR test (if the same assay and sample type used) | High quantitative serology titre (Anti-S) | Likely Reinfection |