CD79A and COVID-19: Our aims are (1) to longitudinally quantify SARS-CoV-2-specific IgA and IgG in human milk of lactating women who received COVID-19 mRNA vaccine, with reference to a cohort convalescent from antenatal COVID-19 as well as a control cohort of healthy lactating women, and (2) to detect and quantify vaccine mRNA in human milk after vaccination.