CD79A and COVID-19: In particular, sample G (IgA+/IgG+/IgM+(low)) was missed by four of five laboratories that used the same commercial IgM-only assay (Euroimmun – Anti-SARS-CoV-2 NCP ELISA IgM) and by two additional assays that should have been able to detect the presence of IgM antibodies based on their technical specifications (AAZ - COVID-PRESTO TROD IgG/IgM; Hangzhou Biotest Biotech - RightSign COVID-19 IgG/IgM Rapid Test Cassette).