Mothers with moderate to severe infection had significantly higher anti-S1RBD-IgA and -IgG concentrations in transitional milk and significantly higher anti-S1RBD-IgA and -IgM concentrations in mature milk than mothers with no to mild COVID-19 symptoms, while anti-S1RBD Ig concentrations in colostrum did not significantly differ between the two groups. Here, CD79A is linked to infection.