COVID-19 Molecular Testing
The molecular COVID-19 test is the gold standard in diagnosing patients with active viral infections. There are molecular test approved for self-collection, the RT-PCR is the most common methodology. John Hopkins Center for Health Security had a comprehensive list of COVID-19 molecular testing methodology.
COVID-19 Antibody Testing
COVID-19 antibody test had not received as much attention as the molecular PCR test where after months of ramping up production still experiencing a shortage every step in the supply chain from swab to reagent to instrumentation. Before FDA tighten the standard, there were test kits being imported oversea that have significant performance issues. Currently there are more than 70 test kits on the FDA removal list.
Antibody testing is a blood test and can be run on high-throughput immunoassay analyzers already in the lab. Since most high volume lab already has lab automation line connected to immunoassay analyzers it is easier for lab to scale up than molecular testing.
- FDA had approved total antibody, IgG and IgM antibody test (There is currently no FDA approved IgA assay)
- Antibody is not recommended nor approved for diagnosis of acute infection or to confirm immunity
- There is no waived antibody test, therefore lab must hold CLIA moderate and high complexity license to perform COVID-19 antibody testing
- PPV (Positive Predictive Value) and NPV (Negative Predictive Value) are dependent on prevalence, FDA assumes a 5% prevalence rate in calculating PPV and NPV. FDA evaluation of PPV and NPV can be found here. https://www.fda.gov/medical-devices/emergency-situations-medical-devices/eua-authorized-serology-test-performance
- Antibody is useful for identifying blood donor for convalescent plasma, population level sero-prevalence study and children with multisystem inflammatory syndrome (MIS-C)