An anti-RBD IgM mAb protects against SARS-CoV-2 infection in differentiated human airway epithelia cultures. (A) Schematic of experimental design using airway epithelial cultures differentiated to an organotypic state at an ALI. (B and C) Quantification of viral RNA copy number in ALI cultures treated with the indicated antibody. Data represent independent experiments; cultures were generated from primary human bronchial epithelial cells derived from unique donors. Each condition was tested in independent duplicates. For B, duplicates were pooled as RNA before quantitative PCR.