COVID-19 RNA has been detected in the breast milk of mothers who are infected, and at least some of the babies of these mothers have also contracted COVID-19. However, it is unclear if transmission occurred via respiratory spread or via breast milk.

Can we sterilize human milk containing SARS-CoV-2 virus and make it safe for infants to drink?

In a Research Brief that is being released by Pediatrics this week, Conzelmann and Groll et al describe their study, in which they added SARS-CoV-2 virus to milk samples obtained from 5 healthy human donors and incubated them for 30 minutes at either room temperature or 63 degrees Celsius (10.1542/peds.2020-031690). This latter technique is called Holder pasteurization, which is used to sterilize donor human milk.

They found that:

• There was no more infectivity in human milk heated to 63 degrees Celsius.
• Even in human milk at room temperature, there was a 41-93% decrease in viral titers (the authors speculate that human milk may have antiviral properties)

So yes, pasteurization can be done. However, is it necessary?

We asked this question of Drs. Lydia Furman and Lawrence Noble. In a commentary, they provide us with a mini lesson in physiology and microbiology, which we encourage everyone, and certainly those caring for newborns being breastfed during this pandemic, to read (10.1542/peds.2020-033852). They have several cautionary points:

• Human milk is unlikely to be infected with SARS-CoV-2, and viral RNA or other particles that can be detected in milk are unlikely to be infectious.
• There have been no reports that link COVID-19 infection in infants with infected breast milk.
• There is no evidence that mothers infected with COVID-19 must express milk to feed their infants, or that the milk must be pasteurized before feeding.
• Holder pasteurization may impact the immunologic profile (e.g., reduced secretory IgA levels) of human milk

Currently, the recommendations support mothers infected with COVID-19 breastfeeding their infant – directly or, if the mother or infant is too ill, via expressed milk. Just because we can pasteurize breast milk doesn’t mean that we should do it, and the recommendations do not call for this.

Concerned parents may ask you about sterilizing their milk – or feeding their baby with formula if they are concerned about COVID-19 transmission. This article and the accompanying commentary have important talking points for you as you provide guidance to concerned parents worried about breastfeeding their infants during the pandemic.