Analytical and Clinical Performance of Two Point of Care Rapid Antibody Assays for SARS-CoV-2

The SARS-CoV-2 pandemic has reached to a state where populations across the world should ad-just to live with it like many other diseases. Regular serosurveys are essential for disease surveil-lance and policy decisions. In this study, we evaluated the analytical and clinical performance of two commercially available rapid antibody assays.

SARS-CoV-2 PCR positive patients (N=104) were recruited for method evaluation study of two commercially available lateral flow Rapid IgM and IgG assays; Edinburgh Genetics ActivXpress+ COVID-19 IgG/IgM Immunoassay Complete Testing Kit (EGCV0092L) and Abchek COVID-19 IgM/IgG Antibody Rapid Test (NUL/COV-19/R&D/001). We have tested all the participants for SARS-CoV-2 with a Rapid Anti-gen Test (Abchek) on the day of sample collection. Additionally, we analyzed vaccinated people (N=187) for seroprevalence of IgG. EP Evaluator version 12 and GraphPad Prism 9.5.0 were used for statistical analysis.

The IgG seropositivity after 10-15 days of PCR positivity was 97.11% (Edinburg Genetics Assay) and 92.30% (Abchek Assay). The Rapid Antigen test was 100% negative with IgM negativity of 93.27% (Edinburg Genetics Assay) and 98.08% (Abchek Assay). The IgG seropositivity of vaccinated participants was 89.84% using both the assays. The IgG sero-positivity was 86.82% (Edinburg Genetics Assay, N=91) and 92.71% (Abchek Assay, N=96) in the study participants with post vaccination.

These assays are robust and scalable. Both the assays can be used for serosurveys with desired scale and speed when a quick observation is needed for surveillance. These tests are cost effective, field deployable without need of any sophis-ticated instruments and large capital.

During a public health emergency like the COVID-19 pandemic, regular sero-surveys are essential for disease surveillance and swift policy decisions. However, deployment of the gold standard methods like quantitative ELISA, neutralizing antibody assays for assessment of population based seroprevalence and immune status becomes logistically difficult, costly and time consuming. The point of care antibody assays are easily scalable, affordable and field deployable. The present study demonstrates that these tests are reliable in terms of analytical and clinical performance. These assays could be used when rapid observations are to be made by including large sample population.