Lactating parents with influenza illness are encouraged to continue breastfeeding while ill. The influenza virus does not spread via breastmilk. Human milk from a lactating parent with influenza contains antibodies and many other bioactive factors that are anti-inflammatory and anti-infective to reduce the risk of significant influenza illness in the breastfed infant (2). Breastfed infants have a lower risk of morbidity and mortality from respiratory illnesses (2).

All influenza vaccines are considered safe during lactation with an increase in antibodies against influenza found in breastmilk among lactating individuals who have received the vaccine (2).

According to the US Centers for Disease Control, pregnant people who are positive for influenza illness around the time of birth should be engaged in shared decision making regarding whether to room-in or to separate, to reduce the risk of neonatal influenza illness (3). There is no documented evidence that separation of the neonate from the lactating parent reduces the risk of neonatal illness or death from influenza. However, there is evidence from the SARS-CoV-2 pandemic that separation of newborns from their mothers immediately postpartum reduces the likelihood of exclusive breastfeeding at the time of hospital discharge (4). Dyads who are not exclusively breastfeeding at the time of hospital discharge are less likely to be breastfeeding at 3 or 6 months postpartum.

Oral oseltamivir remains first line treatment for lactating individuals (1). Although the level of baloxavir is expected to be low in human milk, there is no evidence on the safety of its use during lactation (5). Despite there being no information on the use of inhaled zanamivir during lactation (6), it is not likely to be absorbed by the infant. There is also no information on the use of intravenous peramivir during lactation. Rat studies have demonstrated its presence in milk, approximately 0.5-fold as compared to maternal blood (7), yet it is unlikely to be absorbed by the infant gut.