CD79A and rheumatoid arthritis: There was less reactivity in general for IgA and no difference between rheumatoid arthritis and COVID-19 for both the number of participants with elevated IgA against at least one peptide (16/20 versus 14/20, respectively) or the number of peptides highly bound by IgA (median 1.5/8 versus 1/8 peptides, respectively) when evaluated in a citrulline- or homocitrulline-specific manner.