Response to Daungsupawong and Wiwanitkitre: “Validating Tools to Detect and Inactivate Monkeypox Virus in Human Milk”

Dear Editor:

We appreciate the comment from Daungsupawong and Wiwanitkit ¹ on our recent publication “Validating Tools to Detect and Inactivate Monkeypox Virus in Human Milk.” ² We strive to learn from events such as the COVID-19 pandemic and the monkeypox virus outbreak to improve and perfect our rapid response processes before the next pathogen or other environmental threat occurs. Our goal is to save lives by providing rapid and reliable information to policy makers, health care providers, and the public at crisis onset.

To be both rapid and rigorous, studies need to be limited to critical experiments with validated assays. In the case of monkeypox virus, we have shown that the virus can be detected in human milk should it be contaminated, and that the virus can be inactivated with Holder pasteurization, which is commonly used in donor human milk processing. Although scientifically of interest whether repeated freeze–thaw cycles would affect viral activity, milk banks in the United States usually only allow one freeze–thaw cycle and, in general, parents at home are recommended using their milk after thawing only one time. The virus may lose activity after repeated freeze–thaw cycles or after storage for longer than 1 hour.

However, the presence of an active virus in fresh human milk represents the highest risk for mother-to-child transmission through breastfeeding and needs to be monitored with carefully validated tools. Our study confirmed that we have the tools to monitor and that milk banks have the processing tools to inactivate the virus should it ever gain access to donor human milk.