A Study of Breastfeeding Practices, SARS-CoV-2 and Its Antibodies in the Breast Milk of Mothers Confirmed with COVID-19

Abstract

Background: There have been no confirmed cases of vertical transmission of the 2019 novel coronavirus disease (COVID-19) from mother to child through breastfeeding, but the possibility of COVID-19 transmission to neonates through breast milk has been postulated. Studies on the presence of the ribonucleic acid (RNA) of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in breast milk have shown inconsistent results, and the risk of transmission through breast milk remains unverified. Furthermore, the presence of SARS-CoV-2 antibodies in breast milk, as well as the impacts of prolonged mother-child separation and the cessation of breastfeeding practices due to quarantine control measures have not been reported. Methods: This paper presents the interim results of a multi-center longitudinal study being carried out in Wuhan City of Hubei Province in China. The study began on 10 February 2020, with the aim to describe the short- and medium-term health and developmental outcomes of neonates born to mothers with confirmed/suspected COVID-19. As of 1 April 2020, 24 pairs of pregnant women confirmed with COVID-19 and their neonates (including one pair of twins), 19 pairs of pregnant women suspected with COVID-19 but found to be Polymerase chain reaction (PCR) negative and their neonates, and 21 pairs of pregnant women who were not confirmed with or suspected of COVID-19 and their neonates (control group admitted to hospital due to non-COVID-19 related pregnancy/neonatal complications, including one pair of twins) have been recruited for the study. Telephone follow-up was conducted until 30 April 2020 to collect information on breastfeeding practices, and the length of mother-child separation. Fortyfour breast milk samples were collected from 16 of the 24 mothers with confirmed COVID-19 and tested for the SARS-CoV-2 nucleic acid and antibodies (IgM and IgG). Findings: Among the 24 mothers confirmed with COVID-19, 12 cases presented with symptoms predelivery and 12 cases presented with symptoms during the delivery or post-delivery. The average number of days from the onset of symptoms until recovery with negative PCR testing was 16·4 ± 15·6 days (range 3–62 days). The average mother-child separation time was 36·7 ± 21·1 days, significantly longer than that of the suspected/PCR negative group (16·6 ± 13·1 days) and control group (10·5 ± 8·2 days). Both the COVID-19 confirmed (58·3%) and suspected (52·6%) groups presented significantly lower rates of breastfeeding as compared with the control group (95·2%). Ten out of 14 confirmed mothers who fed their babies with expressed breast milk began expressing breast milk after delivery, but did not initiate feeding breast milk to their baby until between 22–29 days after delivery, primarily due to strict isolation and quarantine measures. Forty-four breast milk samples were collected from 16 of the 24 confirmed mothers. All breast milk samples tested negative for the SARS-CoV-2 nucleic acid. Samples were collected from mothers between 3–79 days from the onset of COVID-19 symptoms. Thirty-eight breast milk samples underwent antibody testing and all tested negative for IgG. Twenty-one breast milk samples from 8 women tested positive for IgM, while the remaining 17 samples from 11 women tested negative. The IgM positive samples were collected on average 30·8 ± 19·4 days from the onset of COVID-19 symptoms, while IgM negative samples were collected on average 43·4 ± 21·3 days after the onset of symptoms. Interpretation: There was no evidence of SARS-CoV-2 in any collected samples of the breast milk. While the IgM antibody was detected in the breast milk of some mothers with confirmed COVID-19, IgG was not detected in the breast milk of any mothers. A longer follow-up period is likely needed to detect IgG antibody. Breastfeeding practices were severely impacted during the COVID-19 epidemic, as the Chinese national guidelines called for suspension of breastfeeding among both confirmed and suspected/PCR negative mothers. Our study also found late initiation of breastfeeding or feeding expressed breast milk to infants even among mothers who were not confirmed with or suspected of COVID-19. Considering the lack of evidence for transmission of SARS-CoV-2 through breast milk, health care workers should provide adequate breastfeeding counseling and support along with appropriate hygiene precautions to all pregnant women and their families. Funding Statement: The study was funded by the Hong Kong Committee for UNICEF. Declaration of Interests: The authors of this paper have no conflict of interest. Ethics Approval Statement: All procedures performed in the study involving the collection of human samples were in accordance with the ethical standards approved by the Ethical Committee of Hubei Provincial Maternal and Child Health Hospital (NO. 2020–IEC–XM010). All participants gave their written permission for both their own and their children’s involvement in the study.