SARS‐CoV‐2 in human milk is inactivated by Holder pasteurisation but not cold storage

Abstract

Aim As the COVID‐19 pandemic evolves, human milk banks world‐wide continue to provide donor human milk to vulnerable infants who lack access to mother's own milk. Under these circumstances, ensuring the safety of donor human milk is paramount, as the risk of vertical transmission of SARS‐CoV‐2 is not fully understood. Here, we investigate the inactivation of SARS‐CoV‐2 in human milk by pasteurisation and the stability of SARS‐CoV‐2 in human milk under cold storage. Methods SARS‐CoV‐2 was experimentally inoculated into human milk samples from healthy donors or into a control medium. Triplicates of each sample were layered onto uninfected cells after Holder pasteurisation (63°C for 30 min), heating to 56°C for 30 min, or after 48 h of storage at 4°C or −30°C. Infectious titres of virus were determined at 72 h post‐infection by endpoint titration. Results Following heating to 63°C or 56°C for 30 min, replication competent (i.e. live) SARS‐CoV‐2 was undetected in both human milk and the control medium. Cold storage of SARS‐CoV‐2 in human milk (either at 4°C or −30°C) did not significantly impact infectious viral load over a 48 h period. Conclusion SARS‐CoV‐2 is effectively inactivated by Holder pasteurisation, suggesting that existing milk bank processes will effectively mitigate the risk of transmission of SARS‐COV‐2 to vulnerable infants through pasteurised donor human milk. The demonstrated stability of SARS‐CoV‐2 in refrigerated or frozen human milk may assist in the development of guidelines around safe expressing and storing of milk from COVID‐19 infected mothers.

Pasteurization Inactivates SARS-CoV-2–Spiked Breast Milk

“…explored the efficiency of holder pasteurization against SARS-CoV-2 in 5 milk samples and found that infectivity of all 5 tested SARS-CoV-2 isolates is completely eliminated by this treatment. This confirms studies where holder pasteurization of milk spiked with three early SARS-CoV-2 isolates prevented viral infection of monkey derived Vero cells[7][8][9] . We verify the efficiency of holder pasteurization upon inclusion of additional viral strains, encompassing the dominant pandemic variant D614G that shows increased fitness in cell culture (Netherlands/01, UKEssen) 10 as well as highly susceptible human Caco-2 cells that express the viral entry factor transmembrane serine protease 2 (TMPRSS2).…”

Detection of breastmilk antibodies targeting SARS-CoV-2 nucleocapsid, spike and receptor-binding-domain antigens

“…At present, the World Health Organization (WHO) recommends that breastfeeding women with suspected or confirmed SARS-COV-2 infection be encouraged to continue breastfeeding as the benefits outweigh the risks [ 13 ]. Holder pasteurization has been shown to eradicate viruses from breastmilk, including SARS-CoV-2 virus [ 3 , 14 ]. Our results show that whilst it does not affect antibody levels in either serum or breastmilk, it decreased the neutralizing capacity of breastmilk SARS-CoV-2 antibodies whilst having no negative effect on serum SARS-CoV-2 neutralization.…”

Potentin vitroanti-SARS-CoV-2 activity by gallinamide A and analogues via inhibition of cathepsin L

“…20 μL of each dilution was then added to cells seeded a day prior at 3×10 3 cells in a volume of 40 μL of MEM-2% FCS per well in a 384-well plate (Corning #CLS3985). The plates containing the cells and compounds were incubated for 30 minutes at 37 °C, 5% CO 2 following which 20 μL of virus solution at 8×10 3 TCID50/mL ( 63 ) was added to the wells. Plates were incubated at 37 °C, 5% CO 2 for a further 72 hours following which the cells were stained with NucBlue dye (Invitrogen, #R37605) according to manufacturer’s instructions.…”