Viral Transmission

by Dr Louise Santhanam, General Practitioner

During simple, common viral illness breastmilk feeding does not need to be interrupted, unless the mother is too unwell to continue (see NHS Choices).  Amongst its many components breastmilk contains immunoglobulins including secretory IgA and oligosaccharides (protective to the GI tract), white blood cells produced in response to maternal infections, viral fragments which can trigger the infant immune system and anti-inflammatory molecules. The maternal entero-mammary and broncho-mammary immune pathways also deliver antibodies to common maternal viral infections via breastmilk to the infant1.

The following information covers the current understanding of the risk of transmission via breastfeeding of significant serious viral infections.  This page is not intended to be a comprehensive resource on all viral transmission issues, but highlights important clinical guidelines that may be useful to the GP.

In clinical practice, where a mother is at risk of transmitting a significant viral illness, we would expect the mother to be under specialist care, or for specialist advice to be sought. The information below is intended as a guide based on nationally and internationally recognised guidance, and is not intended to replace that of an individual’s specialist team. 

Please note- where the guidelines cited on this page recommend avoidance of breastfeeding during nipple fissuring, bleeding or mastitis. this advice is specific to the maternal conditions mentioned and should not be applied to the general population.


British HIV Association (BHIVA) Guidelines Pregnancy Interim update 2014, new guidelines are expected in 2017 – see p50-51 regarding infant feeding. The BHIVA Guidelines state that all mothers known to be HIV positive, regardless of antiretroviral therapy and infant Post Exposure Prophylaxis, should be advised to exclusively formula feed from birth. This is the recommendation for women living with HIV where artificial milk feeding is considered ‘affordable, feasible, acceptable, sustainable and safe’. This is based on evidence from a publication in 2000* in which the frequency of HIV transmission rate via breastfeeding was 16.2% over 2 years.

*This figure comes from a study conducted in Kenya in the 1990s and antiretrovirals were not used by the participants.

British HIV Association & Children’s HIV Association (BHIVA & CHIVA) Position Statement on Infant Feeding in the UK 2010 – The current UK position statement includes the following recommendations (new BHIVA guidelines are expected in 2017):

  • In the UK, mothers known to be HIV infected, regardless of maternal viral load and antiretroviral therapy, should refrain from breastfeeding from birth.
  • All HIV positive mothers in the UK should be supported to formula feed:
    • Mothers should be given advice on artificial milk and bottle feeding equipment.
    • Healthy Start eligibility should be highlighted where relevant.
  • If a mother who is on effective Highly Active Antiretroviral Therapy (HAART) with repeatedly undetectable viral load chooses to breast feed, this should not result in a child protection referral.
  • For UK mothers with HIV who choose to breastfeed:
    • Maternal HAART should be carefully monitored and continued until one week after all breastfeeding has ceased.
    • Breastfeeding, except during the weaning period, should be exclusive and all breastfeeding, including the weaning period, should have been completed by the end of 6 months. [This period has been set as a maximum by the statement].
    • Prolonged infant prophylaxis during the breastfeeding period, as opposed to maternal HAART, is not recommended.
    • Breastfeeding problems such as mastitis and cracked nipples should  be recognised as risk factors for transmission.
    • Intensive HIV monitoring and support for mother and infant are recommended.

WHO Updates on HIV and Infant Feeding 2016 – The recent report from the World Health Organisation (WHO) provides guidelines for countries with high HIV prevalence and settings in which diarrhoea, pneumonia and undernutrition are common causes of infant and child mortality, but is also intended to be applicable to settings with a low prevalence of HIV depending on the background rates and causes of infant and child mortality. The latest recommendation for mothers living with HIV in these settings who are taking antiretroviral therapy (ART) and have no signs of immune or viral failure include:

  • Exclusive breastfeeding to 6 months
  • Introduction of complementary foods after 6 months alongside continued  breastfeeding for at least 12 months
  • Continued breastfeeding for up to 24 months or longer (similar to the general population)
  • While being fully supported for ART adherence

A summary of these recommendations can be found here.

It is important for GPs to be aware that in the UK a considerable proportion of pregnant women living with HIV will have come from countries and communities where breastfeeding is both the norm and a cornerstone of infant and young child survival, and in which avoidance of breastfeeding may result in disclosure of their HIV status2.  Additionally, women who are seeking asylum and have indeterminate right to remain in the UK may face difficulty obtaining formula milk and preparing it safely if returned to their countries of origin.  For such women breastfeeding may be the means whereby they can maintain their child’s food security. In such cases specialist input to facilitate exclusive breastfeeding for the first 6 months and continued breastfeeding in accordance with current WHO HIV and infant feeding guidance, while strictly adhering to ART is critical.

THEREFORE- If a UK mother with HIV chooses to breastfeed, specialist input can facilitate optimisation of the health of mother and infant with meticulous adherence to ART and skilled breastfeeding support.

Mothers living with HIV who abstain from breastfeeding may find this emotionally, financially and socially challenging2. Non-judgemental support from healthcare professionals, peer mentorship and education around developing secure infant attachment are recommended2. Information on infant milks and safe bottle feeding should be provided, as well as signposting those eligible to the Healthy Start scheme.

WHO: Mastitis- Causes and Management 2000 – If a breastfeeding mother with HIV develops mastitis, a fissure or abscess, the WHO recommendation is that she should avoid breastfeeding from the affected side while the condition persists. Breastmilk should be expressed from the affected breast and not fed from that side until mastitis has resolved. Please see the linked document above for further detail.

Breastfeeding Today: Breastfeeding for HIV-Positive Mothers by Pamela Morrison IBCLC, Updated September 2016 – Summarises issues around breastfeeding for mothers living with HIV.

The World Breastfeeding Trends Initiative (WBTi) Report 2016: Indicator 8 Infant Feeding and HIV (see pages 48-50) The WBTi 2016 UK report included an assessment of UK health professional training on infant and young child feeding (IYCF) against the WHO Education Checklist for Lactation. The report identified that misinformation on HIV and infant feeding is widespread, and that healthcare staff and community workers do not receive up-to-date training on the subject.

Hepatitis A

British Association of Sexual Health and HIV (BASHH): UK National Guideline on the Management of the Viral Hepatitidies A, B and C 2015 – See Section 2.8.4. The Guidelines state “The risk [of Hepatitis A transmission] from breast feeding is uncertain, although there are no reported cases of transmission from breast milk. Even if the infant is infected, the disease is normally mild or asymptomatic. Therefore, the balance of risks between infection and stopping breast feeding should be considered on an individual basis”.

Hepatitis B

British Association of Sexual Health and HIV (BASHH): UK National Guideline on the Management of the Viral Hepatitides A, B and C 2015 – See Section 3.8.5.  The Guidelines state “Infants born to infectious mothers are vaccinated from birth. Hepatitis B specific Immunoglobulin 200 IU IM is also given in certain situations where the mother is highly infectious. This reduces vertical transmission by 90%”.

US Centres for Disease Control and Prevention (CDC): Breastfeeding & Hepatitis B Infection Updated June 2015- States that breastfeeding is not a risk for Hepatitis B transmission, and that breastfeeding can begin immediately after birth, and does not need to be delayed until immunisation. The first dose of Hepatitis B vaccine should be given within 12 hours of birth.

Hepatitis C

British Association of Sexual Health and HIV (BASHH): UK National Guideline on the Management of the Viral Hepatitidies A, B and C 2015 – See Section 4.8.5: The Guidelines state “Breastfeeding: there is no firm evidence of additional risk of transmission”.  However, unlike Hepatitis B “there is no clearly demonstrated intervention to reduce HCV transmission from mother-to child” and “Women should be informed of the small potential risk of transmission in pregnancy“. “Vertical (mother to infant) spread also occurs at a low rate (about 5%), but higher rates (7% or more) are seen if the woman is co-infected with HIV. In all groups transmission risk correlates with the quantity of detectable HCV-RNA in the mother’s blood”.

The Hepatitis C Trust: Hepatitis C Information for Women Recommends avoidance of breastfeeding if there is active nipple bleeding, until healing occurs.

US Centres for Disease Control and Prevention (CDC): Breastfeeding & Hepatitis C Infection Updated June 2015 – States there is no data to suggest HCV transmission occurs via breastfeeding or breastmilk but does advise temporary postponement of breastfeeding and discarding expressed milk while nipple bleeding is present (in case of contamination by blood).

Zika Virus

Interim RCOG/RCM/PHE/HPS Clinical Guidelines: Zika Virus Infection and Pregnancy- Information for Healthcare Professionals Updated 17/06/16 – States there is “currently no evidence that Zika virus can be transmitted to babies through breast milk and the advice to mothers to breastfeed remains unchanged” (See section on ‘Transmission’). These guidelines are accessed from the RCOG Statement and Q&A: Zika Virus Infection and Pregnancy.

WHO: Infant Feeding in Areas of Zika Virus Transmission Last update April 2017 – Following a systematic review of cases the WHO recommendation is that mothers who decide to breastfeed should receive skilled support from healthcare workers to initiate and sustain breastfeeding, whether they or their infants have suspected, probable or confirmed Zika virus infection.  “Mothers and families of infants born with congenital anomalies (e.g. microcephaly), or those presenting with feeding difficulties, should be supported to breastfeed their infants”.

NHS Choices: Zika Virus Includes information for pregnant women and information on reducing the risk of Zika infection. States it is safe to use up to 50% DEET while pregnant and breastfeeding, and for infants and children over 2 months old. Also has a link to up to date information from Public Health England on Zika.


  1. Unicef UK Baby Friendly Initiative: Three-day Course in Breastfeeding Management Participant’s Handbook (2008)
  2. Tariq S, Elford J, Tookey P, et al “It pains me because as a woman you have to breastfeed your baby”: decision-making about infant feeding among African women living with HIV in the UK 

Published April 2017