Introduction:
On March 11 2020 the COVID-19 pandemic emergency was declared by the World Health organization (WHO)1. Since then, all obstetric efforts have focused on evaluating the effects of the new coronavirus on pregnancy. At the very beginning of the pandemic, newborns were separated from their mothers with SARS-CoV-2 in order to protect them against the virus and breastfeeding was avoided because it was unknown if the virus could be transmitted via human breast milk. To date, some studies have reported the presence of SARS-CoV-2 in the human breast milk2–5 while others have not6–8, but sample size of these studies is small.
Currently, most healthcare systems and international organizations such as the Centers for Disease Control and Prevention (CDC) recommend breastfeeding for all mothers with SARS-CoV-2 active or past infection, as there appear to be more benefits of breastfeeding than the potential risk of transmission through human breast milk. One of the most important reasons to recommend breastfeeding is the possible passive immunization of newborn against SARS-CoV-29. Several studies have reported the presence of anti-SARS-CoV-2 antibodies10–15 in the human breast milk. Pace et al. have demonstrated that the concentrations of anti-SARS-CoV-2 antibodies correlate with the milk’s ability to effectively neutralize SARS-CoV-2 infectivity16. However, it is uncertain when the antibodies become present and for how long they last in the human breast milk.
The aims of this study were first, to determine the presence of anti-SARS-CoV-2 antibodies in colostrum and mature human breast milk in women who had SARS-CoV-2 infection during pregnancy or at the time of delivery; second, to investigate the correlation between the anti-SARS-CoV-2 antibodies in human milk with the levels of anti-SARS-CoV-2 antibodies in maternal blood, severity of SARS-CoV-2 infection and the time interval from active illness; and third, to evaluate how each immunoglobulin type evolved from the colostrum to the mature milk.