Moreover, little is known about the interpretation of systemic IgA antibody levels for seroprevalence purposes; while secreted IgA has been hypothesized to prevent symptomatic SARS-CoV-2 infection (37), the presence of very high serum IgA levels has been linked with severe infections and age in adult patients (42), and severe infections are unlikely in our young cohort. Here, CD79A is linked to infection.