Scientists say the breast milk of a mother with COVID-19 has tested positive for the coronavirus. It remains unclear though whether the virus can be transmitted in the fluid. 

The correspondence, published in The Lancet, is believed to be the first example of SARS-CoV-2 (the coronavirus causing COVID-19) found in breast milk.

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How did it happen?

In a German hospital, the authors took breast milk samples from two women who had tested positive for SARS-CoV-2. Before a pump was used to collect the milk, the women's nipples were disinfected to prevent the coronavirus from contaminating the milk.

Researchers studied the milk using a "highly sensitive method" to detect and measure rates of the RNA virus, or genetic material, co-author Jan Münch, professor at the University of Ulm's Institute of Molecular Virology, Germany, told NewsWeek.

Once on Days 12 and 13 of her hospital admission, four samples were obtained from one unidentified individual and twice on Day 14. Every time, her milk tested negative. On the first few days of her hospital stay, the woman had moderate COVID-19 symptoms, but not when her milk was taken.

The second mother's milk tested positive for four consecutive days while having mild symptoms of COVID-19. Two tests taken in the early days of her symptoms tested negative.

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Her baby tested the coronavirus positively, but the team is not sure whether the infant caught the virus from the breast milk of the mother or whether there was another mode of transmission. According to the researchers, the mother had been wearing a mask since her COVID-19 symptoms began. She took precautions when handling and feeding her baby, too - including cleaning her hands and breasts and sterilizing pumps and tubes.

Münch emphasized the results are anecdotal, as the team found only the viral RNA in one woman's samples.

Subsequent studies are needed to analyze "in detail" how many nursing mothers carry SARS-CoV-2 RNA in their breast milk, whether the virus is infectious, and whether it can be transmitted to the neonate. Many viruses, such as HIV-1, have been known to be transferred in breast milk.

After the COVID-19 pandemic started five months ago, one of the many concerns that have arisen about the little-understood coronavirus is the potential for the virus to move from mother to infant. Research published in April's New England Journal of Medicine, where three women's breast milk was screened, found no proof of SARS-CoV-2, but it also had a small sample size.

SARS-CoV-2 belongs to a broad family of coronavirus viruses, including SARS-CoV, the cause of extreme acute respiratory syndrome (SARS), MERS-CoV of Middle East Respiratory Syndrome (MERS), and others that induce other common colds. Münch and his team were surprised to find SARS-CoV-2 in the samples since coronaviruses were never detected in human milk, "and thus, SARS-CoV-2 infected mothers were considered safe to breastfeed newborns."

Should mothers avoid breastfeeding during the COVID-19 pandemic?

Münch assumes that asymptomatic mothers do not shed the virus into milk and would still recommend breastfeeding. 

"For symptomatic mothers, one could think about collecting milk and testing it for the presence of SARS-CoV-2 before feeding," he explained. An alternative could be pasteurization, Münch said. However, it has not yet been demonstrated that this procedure inactivates the virus."

U.S.-released breastfeeding guidance Centers for Disease Control and Prevention on May 5 said: "We do not know if mothers with COVID-19 can transmit the virus via breast milk, but the limited data available indicate that this may not be a source of transmission."

"A mother with confirmed COVID-19 should be counseled to take all possible precautions to avoid spreading the virus to her infant, including hand hygiene and wearing a cloth face covering,"

According to Johns Hopkins University, more than 333,000 people have died of COVID-19 in 5.1 million cases worldwide since the late last year. About 1,9 million recuperated men. The United States is the nation with the most reported incidents, according to Statista.

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