CD79A and COVID-19: Indeed, neutralization by IgA, IgM, or S1-specific IgG antibodies was proved in a small subset of 25 samples without measurable antibodies to RBD or N. Hence, it is good news to know that, early in the pandemic, there were many individuals with high-titer responses who were excellent donors for CCP and many COVID-19 patients were treated with high-quality CCP.