Background
The emergence of SARS-CoV-2 has led to the development of serological assays that could aid in an understanding of the burden of COVID-19 disease. Many available tests lack rigorous evaluation and therefore
Conclusion
Excellent sensitivity for IgG detection was obtained over 14 days since onset of symptoms for three SARS-CoV-2 antigens (S, RBD and N) in this multiplexed assay which can also measure antibody functionality.
Methods
A multiplexed solid-phase chemiluminescence assay (Meso Scale Discovery) was evaluated for the simultaneous detection of IgG binding to four SARS-CoV-2 antigens and the quantification of antibody-induced ACE-2 binding inhibition (pseudo-neutralisation assay). Sensitivity was evaluated with a total of 196 COVID-19 serum samples (169 confirmed PCR positive and 27 anti-nucleocapsid IgG positive) from individuals with mild symptomatic or asymptomatic disease. Specificity was evaluated with 194 control serum samples collected from adults prior to December 2019.
Results
The specificity and sensitivity of the binding IgG assay was highest for S protein with a specificity of 97.4 % and sensitivity of 96.2 % for samples taken 14 days and 97.9 % for samples taken 21 days following the onset of symptoms. IgG concentration to S and RBD correlated strongly with percentage inhibition measured by the pseudo-neutralisation assay.