Role of IgM, IgA, and IgG in neutralization (A) Comparison of the SARS-CoV-2 pseudoviral inhibitory dilution (ID 50 ) of all plasma samples. (B–D) ID 50 of plasma from each convalescent donor before and after IgM (B), IgA (C), and IgG (D) depletion. (E) Fold decrease (isotype-depleted versus non-depleted plasma) in ID 50 measured by SARS-CoV-2 pseudoviral particle neutralization. (F and G) Microneutralization assay with infectious wild-type SARS-CoV-2 performed on non-depleted and isotype-depleted plasma from 10 donors. Mean percentage of infection (F) and ID 50 observed from plasma from the 10 donors (G). (H) ID 50 obtained with the pseudoviral particle neutralization assay for the samples in (F)–(G). Asterisks indicate the level of statistical significance obtained by a Wilcoxon signed rank test. n.s., not significant. ∗ p