Promus Diagnostics’ SARS-CoV-2 Quantitative Neutralizing Antibody Test (qNAT) is a functional Enzyme-Linked Immunosorbent Assay (ELISA) intended for qualitative or semi-quantitative detection of total neutralizing antibodies in human serum, K2-EDTA plasma, peripheral blood, and blood plasma that block the binding of SARS-CoV-2 to the human ACE2 receptor of host cells.
There is growing evidence correlating the presence of SARS-CoV-2 infection or vaccination-induced neutralizing antibodies to protective immunity, disease severity, and survival, which has also been observed for numerous other viral infections. The treatment of SARS CoV-2 with purified neutralizing antibodies correlates to reduced viral load.
Vaccine-induced neutralizing antibodies have also been shown to protect against the newly emerged SARS-CoV-2 variants. Neutralization antibodies to natural SARS-CoV-2 infections are generally detectable in the blood several days after initial infection or vaccination — similar to the time frame for the production of IgG binding antibodies. Post-vaccination, functional neutralization antibodies have been shown to be less abundant and are more closely correlated with vaccine efficacy than total IgG binding antibodies.
Although SARS-CoV-2 infected individuals may have detectable antibodies present for several months following seroconversion and the temporal persistence of neutralization antibodies has been shown to decline, there is no evidence supporting their total duration. qNAT is intended for use as an aid in the identification, semi-quantification, and longitudinal monitoring of the neutralizing antibody response to SARS-CoV-2 post-infection and vaccination. This test was developed by GenScript and has been granted Emergency Use Authorization (EUA) by the FDA.