Latest findings by Ulm virologists
New coronavirus detected in breast milk

Ulm University

Virologists in Ulm have detected the new coronavirus (SARS-CoV-2) in the breast milk of an infected woman. Her baby also fell ill with COVID-19. It is not clear, however, whether the child was actually infected via the breast milk or other modes of transmission. The study published as correspondence in the renowned journal 'The Lancet' shows for the first time that SARS-CoV-2 can be present in breast milk.

SARS-CoV-2 is typically transmitted from human to human via droplet infection. Researchers from Ulm University Medical Centre in cooperation with Karin Steinhart from the public health department in Heidenheim were now able to detect SARS-CoV-2 in breast milk. The scientists led by Professor Jan Münch and Rüdiger Groß have tested the breast milk of two infected women for RNA of the new coronavirus.

Both mothers were healthy at the time of delivery and shared a room with each other and their newborns. When one of the women developed disease symptoms, she and her baby were isolated immediately and tested positive for SARS-CoV-2. The second woman, who had been sharing the same room until that point, only started to notice typical symptoms such as coughing, slight fever and a loss of her sense of smell and taste after she was discharged from the clinic. She then also tested positive for SARS-CoV-2.

The researchers tested the milk of both symptomatic mothers. While no evidence of the new coronavirus was found in the breast milk samples of the first mother, the SARS-CoV-2 result was positive in four sequential milk samples of the second mother. The quantitative real-time PCR (RT-qPCR) test not only made it possible to detect the infection, but also to determine the viral load, which was around 100,000 viral genome copies per millilitre of breast milk. After 14 days, when both mothers had recovered, the virus was no longer detectable in the breast milk.

Transmission path not clearly identifiable

Since the onset of symptoms shortly after she had left the hospital, the second mother had been wearing a surgical mask when handling or feeding her baby as well as disinfecting her hands and breasts. She also regularly sterilised the milk pump and other breastfeeding utensils. It nevertheless remains unclear whether the baby was actually infected via the breast milk.

'Our study shows that SARS-CoV-2 is detectable in the milk of one lactating woman with an acute infection. However, we don't know how often this is the case and whether the virus in the milk is actually infectious and transmittable to the baby via breastfeeding,' explains Professor Jan Münch from the Institute of Molecular Virology in Ulm.

The study is a result of the EU project Fight-nCoV. The consortium led by Stockholm University receives around 2.8 million euros over two years through the HORIZON 2020 programme. The study was also supported by the network of Ulm's Collaborative Research Centre 1279 for the research on endogenous peptides ('Utilisation of the human peptidome for the development of new antimicrobial and anticancer therapeutic agents').

Rüdiger Groß, Carina Conzelmann, Janis A. Müller, Steffen Stenger, Karin Steinhart, Frank Kirchhoff, Jan Münch. Detection of SARS-CoV-2 in Human Breast Milk. The Lancet. text

Correspondence pieces represent the views of the authors and not necessarily the views of The Lancet or any Lancet specialty journal. This correspondence was peer-reviewed.

Text and mediacontact: Annika Bingmann

Prof. Jan Münch
Prof. Jan Münch conducts research at the Institute of Molecular Virology at Ulm University (photo: Ulm Medical Centre)