The World Health Organization (WHO) states that they have "carefully investigated the risks of women transmitting COVID-19 to their babies during breastfeeding" and determined that, based on available evidence, the benefits of the breastfeeding outweigh any potential risks of COVID-19 transmission. This is based on the data that, "children are at relatively low-risk of COVID-19, but are at high risk of numerous other diseases and conditions that breastfeeding prevents." People who have given birth should be encouraged to stay with their infants and breastfeed them, regardless of COVID-19 infection status, unless they are too unwell to do so. Only fragments of the virus have been detected in breastmilk this far, and not live virus, so there is no established risk of infection directly through the milk. See the complete WHO factsheet on breastfeeding and COVID-19 here.