Evaluation of a COVID-19 IgM and IgG rapid test; an efficient tool for 4 assessment of past exposure to SARS-CoV-2

COVID-19 is the most rapidly growing pandemic in modern time, and the need for 21 serological testing is most urgent. Although the diagnostics of acute patients by RT-PCR is 22 both efficient and specific, we are also crucially in need of serological tools for investigating 23 antibody responses and assessing individual and potential herd immunity. We evaluated a 24 commercially available test developed for rapid (within 15 minutes) detection of SARS-CoV-25 2-specific IgM and IgG by 29 PCR-confirmed COVID-19 cases and 124 negative controls. 26 The results revealed a sensitivity of 69.0 % and 93.1 % for IgM and IgG, respectively, based 27 solely on PCR-positivity due to the absence of a serological gold standard. The assay 28 specificities were shown to be 100 % for IgM and 99.2 % for IgG. This indicates that the test 29 is suitable for assessing previous virus exposure, although negative results may be unreliable 30 during the first weeks after infection. More detailed studies on antibody responses during and 31 post infection are urgently needed.