We detected RBD-specific IgA, IgG, and IgM in milk obtained between three and 33 days after a positive COVID-19 test in 73%, 90% and 50% of the women, respectively, reinforcing the finding that SARS-CoV-2 infection elicits a robust humoral immune response in the breastmilk of lactating women (4, 5, 7–10, 28). Here, CD79A is linked to COVID-19.