A Chinese lab study suggests that breast milk may help protect babies from being infected by the novel coronavirus.
The study shows it to be even more effective than the milk of other animals such as goats and cows, reports The Daily Mail.
Researchers found that mother's milk prevented the pathogen from infecting and replicating in cells, even if the child does not have antibodies
The team, from Beijing University of Chemical Technology, says the findings support the recommendation from the World Health Organisation (WHO) that mothers with suspected or confirmed Covid-19 be encouraged to continue breastfeeding.
For the study, published on pre-peer review site bioRxiv.org, the team exposed human lung and gut cells to SARS-CoV-2 and later analysed what effect breast milk, which was collected in 2017 - before the pandemic - had on the cells.
Healthy cells were mixed into human breast milk. Then the milk was washed off and the cells were exposed to the virus.
The virus did not bind to or enter most of the cells. Additionally, if it did enter cells, the virus was not able to make copies of itself.
This suggests breast milk can inhibit the coronavirus as it does other viruses such as norovirus and bacteria.
'SARS-CoV-2 could infect [cells] and the infection could be inhibited by breast milk (2 mg/ml) , which was reported to have anti-SARS-CoV-2 activity,' the authors wrote.
In a previous study, the same research team found breast milk prevented coronavirus infection in animal kidney cells.
They determined the whey protein, which has anti-inflammatory properties, was responsible for inactivating the virus rather than other proteins such as lactoferrin.
'Whey protein from human breast milk effectively inhibited...SARS-CoV-2...by blocking viral attachment, entry and even post-entry viral replication,' they wrote.
This was also true when milk was tested from those of other animals including cows and goats.
However, the whey from animals suppressed the viral strains by approximately 70 percent compared to the nearly 100 percent of human whey.
A national study is currently being launched by Washington State University to determine whether or not babies can contract coronavirus from breastfeeding.
Limited research has been conducted on this topic up to this point, but the results have been mixed.
Some studies have found no virus in human milk while others have detected viral RNA in just certain milk samples.
For example, at least two studies, one from China and another from the US, found no evidence of SARS-CoV-2 in human breastmilk.
But a report from the WHO found that, of 46 breast milk samples from mothers with the virus, 43 came came back negative while three tested positive for particles.
However, the team says that even if viral genetic material is found in breast milk, it doesn't mean it's infectious or can be spread to babies.