Virucidal Efficacy of Holder Pasteurization of Breast Milk in a Portable Device

Breast milk is the optimal nutrition for infants. However, a number of viruses can accumulate in breast milk and be transmitted to a newborn during breastfeeding. Holder pasteurization is a gold-standard method for breast milk treatment, achieving an acceptable compromise between microbiological safety and biological quality. We have evaluated the virucidal activity of Holder pasteurization of breast milk contaminated with RNA and DNA viruses in a portable home-use pasteurizer. Viruses were selected on basis of their ability to infect humans, contaminate breast milk, and pose a threat for a newborn. The efficacy was evaluated in experimental conditions using breast milk samples from four different donors. Infectious virus and viral genome content were assessed. Holder pasteurization resulted in a decrease in infectivity below the detection limit for enveloped RNA viruses (HIV-1, CHIKV, and SARS-CoV-2), but not RSV, and a partial decrease in infectious virus titer for non-enveloped RNA enteroviruses (EV-A71, E30, and PV1), and DNA viruses (hAdV5 and HSV-1). Moreover, infectivity reduction in E30 and PV1 in different samples of breast milk significantly differed. Therefore, Holder pasteurization can be a tool in the novel pandemic preparedness toolbox or probably help mothers manage breastfeeding during common infections.