Conclusions:
No SARS-CoV-2 virus was found in human breast milk and anti-SARS-CoV-2 antibodies were present in both the colostrum and mature milk, irrespective of the time when the infection occurred during the pregnancy. IgA was the predominant immunoglobulin found in human breast milk and its concentrations were significantly lower in the mature milk than in the colostrum. Women who had SARS-CoV-2 pneumonia during pregnancy or at delivery had higher levels of IgG and IgA in the colostrum than those who were asymptomatic or with mild symptoms.