Table 3 Expected variation in positive predictive value (i.e. probability that a case meeting the diagnostic criteria is truly ill with COVID-19) by COVID-19 incidence
From: Considerations for planning COVID-19 treatment services in humanitarian responses
| COVID-19 incidence | Background incidence of diseases with overlapping signs and symptoms (consider the patient’s age and comorbidities, the geographic setting and season) | Modality of COVID-19 diagnosis | |
|---|---|---|---|
| Testing | Syndromic | ||
|
High (around the peak) | Low | Very high | High |
| High | Very high |
Low to moderate (for mild and moderate cases) Moderate to high (for severe cases) | |
|
Medium (just after or just before the peak) | Low | Very high |
Moderate to high (for mild and moderate cases) High (for severe cases) |
| High | High |
Moderate (for mild and moderate cases) Moderate to high (for severe cases) | |
|
Low (early or late in the epidemic) | Low | High |
Low to moderate (for mild and moderate cases) Moderate to high (for severe cases) |
| High | Moderate to high (depends on test specificity) |
Very low (for mild and moderate cases) Low (for severe cases) | |