Distinct early IgA profile may determine severity of COVID-19 symptoms: an immunological case series

Christine Dahlke; Jasmin Heidepriem; Robin Kobbe; Rene Santer; Till Koch; Anahita Fathi; My L. Ly; Stefan Schmiedel; Peter H. Seeberger; Marylyn M. Addo; Felix F. Loeffler

Peptide microarrays were employed to obtain a more comprehensive view of B-cell dynamics and a deeper understanding of the development of specific B-cell epitopes during the course of the infection. We investigated the dynamics of IgA, IgG, and IgM antibody responses in very mild compared to more severe SARS-CoV-2 infections during the acute and convalescent phases. The induction of early, strong antibody response was recently reported. 9 In this study, seroconversion occurred at day 7 post onset of symptoms in 50% of infected individuals. Another study underlined the early responses of IgA, IgM and IgG following SARS-CoV-2 infection. 10 The authors report a median duration of IgM and IgA antibody detection of 5 days (IQR 3-6). Furthermore, Okba et al. 11 analyzed IgA and IgG responses in two mild and one severe case using an in-house S1-ELISA. They observed a similar trend with an increase in the IgA response over time in a more severe case. An early IgA response as seen in our patients #2 and #4 was not observed, which might be due to differences in the patients (sample collection dates) or assay performance. Key differences are the limitation of only using S1-proteins for the ELISA (vs. whole proteome on the microarray) and a higher sensitivity of peptide arrays.