ABSTRACT
Background: Understanding the profile of antibody responses following acute COVID-19 infection is required. Aim: to describe the pattern of IgG anti-COVID-19 antibody production in patients with acute infection using the LABScreen COVID Plus assay. Results: The overall seropositivity was 69/73(94.5%). Anti-Spike, Spike 1 and spike S2 subunits were positive in 78.1%, while anti spike receptor binding domain (RBD) was detected in 68.4% and anti nucleocapsid protein in 61.6%. The overall positivity of the assay reached 100.0% during the second week post symptoms. The mean fluorescent intensities (MFI) of anti-Spike S1 was higher in the second week than the first week, p=0.03. MFI of anti-Spike S2 was significantly higher in PCR positive patients in comparison with the negative ones, p=0.006. When compared to the RT-PCR results;the overall antibodies positivity, anti-Spike, and anti-Spike2 antibodies had sensitivities (100% and 84.7%) and specificities (28.6% and 50.0%) and accuracies (86.3% and 78.1%). Patients' outcome correlated significantly with the time of hospital admission, p=0.001. Conclusion: COVID-19 IgG antibodies are detectable with considerable frequencies during the first two weeks post infection. Anti S2 antibodies correlates well with the RT-PCR results. The LABScreen COVID Plus is a sensitive assay for the detection of post-acute COVID-19 infection antibody responses. © 2020 The author (s).