Main findings
The study has demonstrated that, firstly, all 59 human breast milk tested negative for rRT-PCR SARS-CoV-2; secondly, antibody levels against SARS-CoV-2 present in the colostrum and mature milk do not seem to vary significantly in relation to the time when infection has occurred during pregnancy; thirdly, IgA is the predominant immunoglobulin found in human breast milk and its concentrations are significantly lower in the mature milk compared to the colostrum; and fourthly, women with SARS-CoV-2 pneumonia have higher levels of both IgG and IgA in the colostrum than those who are asymptomatic or with mild symptoms.