Mapping antibody reactivity in COVID-19 patients by using multi-coronavirus protein microarray In an exciting, state-of-the-art study currently available on the medRxiv* preprint server, US researchers created a multi-coronavirus protein microarray containing full-length proteins, peptide libraries, and overlapping protein fragments from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as well as four other human coronaviruses. They demonstrated that this technology could be used for mapping antibody reactivity in coronavirus disease (COVID-19) patients. Previous studies have demonstrated that patients with COVID-19 swiftly seroconvert to SARS-CoV-2, which means they produce Immunoglobulin IgA, IgG, and IgM antibodies directed against several viral proteins. Nonetheless, it is not completely clear whether all antibody responses are beneficial for us, or some can actually lead to a less favorable course of the disease.