TABLE 7.
Guidance for selecting a SARS-CoV-2 serologic testing strategy depending on intended use and COVID-19 prevalencea
| Intended use | Most valued test characteristic(s) | Rationale | Suggested testing strategy if disease prevalence is: |
|||
|---|---|---|---|---|---|---|
| Low (≤1%) | Moderate (3%) | High (10%) | Very high (25%) | |||
| Routine diagnosis of COVID-19 in patients with recent URI symptoms and negative PCR result from respiratory tract sample(s) | High sensitivity in early infection; high NPV (≥95%) | Important not to miss true cases; false-positive results are not desirable but are more tolerable than false-negative results | Single Ab test | Single Ab test | Single Ab test | Single Ab test |
| Assessing candidacy for exptl COVID-19 therapeutics in PCR-negative patients with respiratory symptoms | High PPV (≥95%) and NPV (≥95%) | Need high NPV to ensure appropriate candidates get needed therapeutics; need high PPV so that inappropriate candidates do not receive drugs that are in short supply | 2-test strategy | 2-test strategy | 2-test strategy | Single nucleocapsid Ab test or 2-test strategy |
| Identifying potential convalescent-phase plasma donors | Very high PPV (>99%) | Important that plasma donors have SARS-CoV-2 serum antibodies; high NPV is less important because potential plasma donors are abundant | 2-test strategy | 2-test strategy | 2-test strategy | 2-test strategy |
| Assessing for past exposure in population studies | High sensitivity in convalescence and high NPV (≥95%) | High PPV not critical because results will not be used to inform clinical decision-making; more important to identify all true cases | Single Ab test | Single Ab test | Single Ab test | Single Ab test |
| Assessing for past exposure to determine immune status | Strong correlation between detected antibody response and presence of neutralizing antibodies; high PPV (≥95%) and NPV (≥95%) | None of the tests evaluated in this study is claimed to be a tool for determining immunity to SARS-CoV-2 infection; however, studies suggest that spike protein antibodies correlate with neutralizing antibodies better than nucleocapsid antibodies dob | Assess for Ab response with a 2-test strategy including a spike protein Ab test; assess for immunity among seropositive patients using a neutralizing Ab test or another test known to correlate with a neutralizing Ab response | Assess for Ab response with a 2-test strategy including a spike protein Ab test; assess for immunity among seropositive patients using a neutralizing Ab test or another test known to correlate with a neutralizing Ab response | Assess for Ab response with a 2-test strategy including a spike protein Ab test; assess for immunity among seropositive patients using a neutralizing Ab test or another test known to correlate with a neutralizing Ab response | Assess for Ab response with a 2-test strategy including a spike protein Ab test; assess for immunity among seropositive patients using a neutralizing Ab test or another test known to correlate with a neutralizing Ab response |
a
Abbreviations: URI, upper respiratory tract infection; NPV, negative predictive value; PPV, positive predictive value; Ab, antibody.
b
See reference 20.