Before patient specimen testing, Quest verifies the performance characteristics of the FDA emergency use authorized assays by completing CLIA/CAP-specified in-laboratory verification using stringent acceptability criteria for precision, reproducibility, accuracy, method comparison, cross-reactivity, and clinical performance. Highlights of the manufacturers’ clinical performance of the SARS-CoV-2 IgG and IgM kits used at Quest are as follows:
1. SARS-CoV-2 Antibody (IgG), Nucleocapsid, Qualitative (test code 39749; also a component of the IgM/IgG panel [test code 31672])
a. Estimated assay sensitivity is >99.6% for specimens collected at least 15 days post–symptom onset,4 based on positive percent agreement (PPA)3 of SARS-CoV-2 IgG serology results among SARS-CoV-2 RNA−positive patients.4
b. Estimated assay specificity4 is >99.9%, based on negative percent agreement (NPA)3 assessed by performing cross-reactivity studies utilizing serum specimens positive for antibodies to other respiratory viruses pre– and post–COVID-19 time periods.4
2. SARS-CoV-2 Antibodies (IgG Nucleocapsid, IgM Spike), Qualitative (test code 31672)
a. Estimated assay sensitivity is 95% for specimens collected at least 15 days post–symptom onset,5 based on PPA3 of SARS-CoV-2 IgM serology results among SARS-CoV-2 RNA–positive patients.5
b. Estimated specificity5 is 99%, based on NPA3 assessed by performing SARS-CoV-2 IgM tests on serum specimens positive for antibodies to other respiratory viruses pre– and post–COVID-19 time periods.5
3. SARS-CoV-2 Antibody (IgG), Spike, Semi-Quantitative (test code 34499)
a. Estimated assay sensitivity is >99.9% for specimens collected at least 15 days post–symptom onset,6,7 based on PPA3 of SARS-CoV-2 IgG serology results among SARS-CoV-2 RNA−positive patients.6,7
b. Estimated assay specificity is approximately6,7 99.9%, based on NPA3 assessed by performing cross-reactivity studies utilizing serum specimens positive for antibodies to other respiratory viruses pre– and post–COVID-19 time periods.6,7
4. SARS-CoV-2 Total Antibody, Spike, Semi-Quantitative (test code 39820)
a. Estimated assay sensitivity is >99.9% for specimens collected at least 15 days post–symptom onset,8 based on PPA3 of SARS-CoV-2 IgG serology results among SARS-CoV-2 RNA−positive patients.8
b. Estimated assay specificity is approximately8 99.9%, based on NPA3 assessed by performing cross-reactivity studies utilizing serum specimens positive for antibodies to other respiratory viruses pre– and post–COVID-19 time periods.8