Serology assessment of antibody response to SARS-CoV-2 in patients with COVID-19 by rapid IgM/IgG antibody test

De Marinis, Y.; Sunnerhagen, T.; Bompada, P.; Blackberg, A.; Yang, R.; Svensson, J.; Ekstrom, O.; Eriksson, K.-F.; Hansson, O.; Groop, L.; Goncalves, I.; Rasmussen, M.

The coronavirus disease 2019 (COVID-19) pandemic has created a global health- and economic crisis. Lifting confinement restriction and resuming to normality depends greatly on COVID-19 immunity screening. Detection of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which causes COVID-19 by serological methods is important to diagnose a current or resolved infection. In this study, we applied a rapid COVID-19 IgM/IgG antibody test and performed serology assessment of antibody response to SARS-CoV-2. In PCR-confirmed COVID-19 patients (n=45), the total antibody detection rate is 92% in hospitalized patients and 79% in non-hospitalized patients. We also studied antibody response in relation to time after symptom onset and disease severity, and observed an increase in antibody reactivity and distinct distribution patterns of IgM and IgG following disease progression. The total IgM and IgG detection is 63% in patients with < 2 weeks from disease onset; 85% in non-hospitalized patients with > 2 weeks disease duration; and 91% in hospitalized patients with > 2 weeks disease duration. We also compared different blood sample types and suggest a potentially higher sensitivity by serum/plasma comparing with whole blood measurement. To study the specificity of the test, we used 69 sera/plasma samples collected between 2016-2018 prior to the COVID-19 pandemic, and obtained a test specificity of 97%. In summary, our study provides a comprehensive validation of the rapid COVID-19 IgM/IgG serology test, and mapped antibody detection patterns in association with disease progress and hospitalization. Our study supports that the rapid COVID-19 IgM/IgG test may be applied to assess the COVID-19 status both at the individual and at a population level.