Photo: Jacques Nadeau Le Devoir
Breast milk is known to “promote the development of the immune system and to provide a first line of defense against respiratory infections and gastro-intestinal”, remind the authors of the study.
Moms who need breast milk bank donors can be reassured. Even if this milk was donated by a woman infected by the coronavirus, the pasteurization process in which the bank submits all the gifts of milk completely inactivates the SARS-CoV-2, confirms a study published July 9 in the Journal of the canadian medical Association (CMAJ).
It was important to know if the coronavirus responsible for the COVID-19 could be eliminated from the breast milk by the usual treatment of pasteurization, as the administration of breast milk from donors is part of the care we give to newborns of very small weight (less than 1500 grams) until the mother to produce enough. Breast milk is known to ” promote the development of the immune system and to provide a first line of defense against respiratory infections and gastro-intestinal “, remind the authors of the study.
Several viruses, including HIV and hepatitis, can be passed through breast milk. This is not yet confirmed in regard to the SARS-CoV-2, but at least three studies have reported the presence of the virus in breast milk. These studies, however, have not verified the viability of the virus.
Given this possibility of transmission by the mammary glands, as well as from contamination by respiratory droplets, through the skin, through the breast milk and the milk containers, the specialist in neonatology at Sinai Health, Dr. Sharon Unger, a professor at the University of Toronto and medical director of the Rogers Hixon Ontario Human Milk Bank, and his colleagues wanted to investigate if the technique of pasteurization used by more than 650 milk banks around the world, including all canadian banks, was adequate to neutralize the SARS-CoV-2.
The technique in question is the Holder method, which involves heating the milk to 62.5 °C for 30 minutes and that is effective to inactivate most of the viruses known to be transmitted through breast milk.
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Researchers have therefore introduced a viral load of SARS-CoV-2 in samples of breast milk. A portion of these samples were left at room temperature for 30 minutes, while the other half was introduced into a hot water bath and maintained at 62.5 °C for 30 minutes. No virus activity was not detected in all the samples that have been pasteurized by the Holder method.
However, the researchers have noted that this heat treatment does not inactivait not completely the virus present in samples controls free of breast milk. According to the authors of the study, this last observation indicates that the biological environment in which the virus must be taken into consideration when one evaluates the conditions of inactivation supposed to be effective “.
Interesting fact : the researchers also noted a reduction of the deleterious effects of coronavirus on the cells in milk samples contaminated with SARS-CoV-2, which remained at room temperature and which had not been pasteurized. According to the authors of the study, ” this decrease is likely the result of multiple components of the immune found in breast milk, including antibodies IgA, of lactoferrin, lactadherin, of mucins and oligosaccharides, which all have an important antiviral activity “.
Mothers can therefore sleep soundly at night, the pasteurization by the method of Holder which is carried by all milk banks canada inactive all SARS-CoV-2, which could have contaminated the milk.