CD79A and COVID-19: As well, when the concentration of IgA required to achieve 50% neutralization (IC50) was determined, 7/8 pre-pandemic controls did not achieve 50% neutralization (IC50>200ug/mL while, for the COVID-19 samples, 2/8 did not achieve 50% neutralization, and the mean IC50 for the 6 COVID19 specimens that displayed neutralizing activity was 33.6ug/mL of total IgA (range, 2.39–89.4ug/mL; Fig 4c).