Since its identification in December of 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has continued to spread rampantly around the world and remains a major threat to worldwide public health. The novelty of SARS-CoV-2 raised serious concerns regarding nursing mothers' vulnerability and whether they could transmit the infection to their babies during breastfeeding.
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Maternal health and COVID-19
Previous outbreaks throughout history led to the suggestion that maternal and neonatal outcomes may be at a higher risk of unfavorable outcomes following exposure to SARS-CoV-2.
Overall, current evidence suggests that whilst the overall risk of severe illness is low, pregnant women are at a higher risk of severe illness with COVID-19 as compared to the normal population. The risk of severe illness increases in older prospective mothers and those with preexisting conditions.
Where complications do occur regarding COVID-19 and pregnancy, evidence suggests this is most likely in the third trimester and so mothers are advised to be especially cautious during this period. COVID-19 illness may affect pregnancy outcomes, such as preterm birth.
SARS-CoV-2 has been found to directly infect cells through its interaction with the angiotensin-converting enzyme 2 (ACE2) receptor. During pregnancy, ACE2 receptor levels are upregulated, accounting for the relatively low blood pressure levels that pregnant women will experience.
As a result of this increased expression of ACE2, pregnant women may be at a higher risk of developing serious complications from SARS-CoV-2 expression. As the clinical situation continues to develop, research on both the short- and long-term effects that COVID-19 has on maternal, fetal, and neonatal outcomes continues to provide more evidence.
Can SARS-CoV-2 enter breastmilk?
One major concern that has emerged during this pandemic surrounding maternal health is the possible transmission of COVID-19 through breast milk. Published data on this subject is ongoing, but current evidence suggests that breast milk is unlikely to transmit COVID-19 infection.
The Centers for Disease Control and Prevention (CDC) advises that mothers without suspected or confirmed COVID-19 do not need to take special precautions when breastfeeding, but should learn how to properly sanitize their breast pump.
For mothers with suspected or confirmed COVID-19, the CDC advises that it is typically safe to breastfeed, but precautions should be taken including rigorous handwashing before and after breastfeeding, cleaning breast pumps and wearing a mask.
For more detailed information on different scenarios involving COVID-19 infection and breastfeeding, quarantine restrictions and what to do if the mother is uncomfortable breastfeeding or bottle-feeding their child or too unwell to do so, see the CDC website here.
Even though the potential for COVID-19 transmission through breast milk appears to be low with no evidence of it doing so, it is crucial that positive mothers strictly abide by additional precautions if they are COVID-19 positive, as they can still transmit the virus to their young babies through respiratory droplets and/or skin contact during breastfeeding.
A study published in The Lancet Global Health in February 2021 looked into global public health approaches to mothers and breastfeeding infants. It concluded that current evidence supports mother-infant close contact and breastfeeding even in COVID-19 positive mothers whilst taking precautions to prevent respiratory spread. It states that the survival benefits of breastfeeding outweigh the case fatality rate (CFR) for COVID-19 positive infants (which is very low).
The same study presents evidence showing that whilst SARS-CoV-2 RNA has been identified intermittently within breastmilk, there is no evidence of transmission competent SARS-CoV-2 in breastmilk or of transmission through breastfeeding.
Can breast milk help prevent COVID-19 in babies?
Human breast milk contains a wide range of soluble and cellular antimicrobial substances that contribute to the development and maturation of the immune system in infants.
Although some of the substances found in breast milk could be beneficial to newborns during COVID-19, researchers maintain that there must be a balance between the protective inflammatory substances and those that modulate inflammation to protect the newborn against infection.
Some anti-inflammatory substances found in human breast milk include osteoprotegerin, which has been suggested to reduce the inflammatory response by preventing tumor necrosis factor (TNF)-induced inhibition of T cells.
Another anti-inflammatory substance found in human breast milk is lactoferrin, which has been shown to reduce the production of proinflammatory cytokines. Molecules like lactoferrin have potential anti-SARS-CoV-2 activity. Epidermal growth factor (EGF) has similar anti-inflammatory properties and can be found in higher concentrations in preterm milk as compared to full-term milk.
Aside from breastmilk's inherent properties, SARS-CoV-2 antibodies have been identified in breastmilk and studies have pointed to the transmission of these antibodies from previously positive mothers to their infants.
Breastfeeding during COVID-19
Neonatal health and COVID-19
Infants under the age of one month are theoretically at particular risk of experiencing the severe effects of COVID-19 due to immature host defense mechanisms. However, recent studies point to a potential advantage that the naïve neonatal immune system has in its inability to produce the cytokine storm linked to many of the severe and even fatal results of COVID-19.
Additionally, the cells present within children’s lungs express this receptor much less than that which is present in adults' lungs, which is a suggested reason for infection by SARS-CoV-2 typically affecting children less severely.
Even so, the uncertainty surrounding the effects of COVID-19 perpetuates the need to protect the neonatal population from any potential exposure to SARS-CoV-2, including that which might arise during breastfeeding.
As mentioned earlier, a recent study on the public health approach to mother-infant globally concluded that the survival benefits of breastfeeding and close contact outweigh the very low CFR rate in neonates with COVID-19. In the evidence they looked at, most COVID-19 neonatal deaths occurred in preterm babies or those with seriously ill mothers who were separated from them.
Current evidence, agreed by the CDC, suggests that it is uncommon for neonates to become infected with SARS-CoV-2, and those who do are mostly asymptomatic or experience mild symptoms, going on to recover. Severe illness, whilst reported, seems to be rare. Underlying medical conditions and preterm birth may increase the risk of severe illness.
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Overall, current evidence suggests that COVID-19 transmission from mother to infant is a risk through respiratory mechanisms, but not through breastmilk. Hence, organizations like the CDC currently advise COVID-19 positive mothers that breastfeeding is generally safe when precautions are taken to reduce respiratory transmission.
- Centers for Disease Control and Prevention. 2020. Coronavirus Disease (COVID-19) and Breastfeeding. Available from: https://www.cdc.gov/breastfeeding/breastfeeding-special-circumstances/maternal-or-infant-illnesses/covid-19-and-breastfeeding.html [Accessed 16 March 2021]
- Centers for Disease Control and Prevention. 2020. Evaluation and Management Considerations for Neonates At Risk for COVID-19. Available from: https://www.cdc.gov/coronavirus/2019-ncov/hcp/caring-for-newborns.html [Accessed 16 March 2021]
- Giuliani, C., Li Volsi, P., Brun, E., et al. (2020). Breastfeeding during the COVID-19 pandemic: Suggestions on behalf of woman study group of AMD. Diabetes Research and Clinical Practice 165. doi:10.1016/j.diabres.2020.108239.
- Gao, X., Wang, S., Zeng, W., et al. (2020). Clinical and immunological features among COVID-19 affected mother-infant pairs: antibodies to SARS-CoV-2 detected in breast milk. New Microbes and New Infections. doi:10.1016/j.nmni.2020.100752.
- Green, J., Petty, J., Bromley, P., et al. (2020). COVID-19 in babies: Knowledge for neonatal care. Journal of Neonatal Nursing 26(5); 239-246. doi:10.1016/j.jnn.2020.06.005.
- Narang, K., Enninga, E. A. L., Gunaratne, M. D. S. K., et al. (2020). SARS-CoV-2 infection and COVID-19 during pregnancy: A multidisciplinary review. Mayo Clinic Proceedings 95(8); 1750-1765. doi:10.1016/mayocp.2020.05.011.
- Rollins, N. et al. (2021). A public health approach for deciding policy on infant feeding and mother–infant contact in the context of COVID-19. The Lancet Global Health. doi.org/10.1016/S2214-109X(20)30538-6
- Wu, Y., Liu, C., Dong, L., et al. (2020). Coronavirus disease 2019 among pregnant Chinese women: case series data on the safety of vaginal birth and breastfeeding. BJOG: An International Journal of Obstetrics and Gynecology 127(9);1109–1115. doi:10.1111/1471-0528.16276.