The Q-lisa® COVID-19 ELISA Antibody Test (IgG) is an in-vitro qualitative enzyme immunoassay -intended for the detection of specific IgG antibodies against SARS CoV-2 in human plasma and serum. The nucleocapsid protein (N-protein) of SARS CoV-2, pre-coated on to the micro titer plate wells will bind with the specific COVID-19 IgG present in the infected test serum. The Ag-Ab complex will be then reversely captured by the addition of IgG-HRP and eventually will generate a colour following the addition of chromogenic substrate.

Hence during the symptomatic phase of the disease, the viral RNA may no longer be detectable, the persistence of the COVID- 19 IgG antibodies proves to be a valuable tool in identifying people who have been infected and likely to recover from the illness. Though it is unknown that the IgG against SARS CoV-2 confer any immunity yet, its detection plays an important role in sero surveillance. In India, the ICMR has recommended these tests for conducting sero-surveillance to determine the burden of COVID-19 at the community level and monitor the trends in the transmission of SARS-CoV-2 infection.