General considerations

It is important to complete an individual risk assessment for your patient and to apply the principles of prescribing in breastfeeding when looking at the available information and making treatment decisions.

Recommendations

There is no risk to breastfed infants after administration of inactivated vaccines.

Live, attenuated vaccines are also not considered to pose a risk to the infant except yellow fever vaccine.

Although vaccines are compatible with breastfeeding, their use should be limited to those situations where there is a clinical risk of maternal exposure to the infecting organism. This includes risks due to domestic, occupational and travel exposure.

Childhood immunisations

The infant should receive all vaccines used in childhood immunisation programmes even if the mother receives the vaccine separately.

There is also limited evidence which shows that infants who were breastfed produced better antibody responses to some childhood immunisations compared to those who were formula fed.

Clinical Considerations

Antibodies and other protective bioactive factors generated in response to the vaccine can pass through to the infant via breast milk.

Mercury content

Some vaccines contain thiomersal as a preservative. However, the small amount of mercury present is not considered to present a risk to a breastfed infant.

Live vaccines

In the case of live vaccines, if there is any concern that the infant may be immunosuppressed, contact our specialist service, the UK Drugs In Lactation Advisory Service (UKDILAS), for further advice.

COVID-19 vaccines

It is recommended that COVID-19 vaccination should be given during breastfeeding, if the person is eligible.

Yellow fever vaccine

Administration of the yellow fever vaccine should generally be avoided during breastfeeding. There have been a few case reports of yellow fever encephalitis in infants due to breast milk transmission of the virus from the vaccine. However, the vaccine may still be indicated in certain circumstances, for example in the case of an outbreak.

If yellow fever vaccine is being considered during breastfeeding, contact our specialist service, the UK Drugs in Lactation Advisory Service, for further advice.

Infant monitoring

Side effects in the breastfed infant from exposure to a vaccine through breast milk are highly unlikely. As a precaution, monitor the infant for any unusual signs and symptoms.

Further advice

Advice on the use of vaccines, including during breastfeeding, is published in Immunisation against infectious disease: the green book.

Contact us

Get in touch with the UK Drugs In Lactation Advisory Service (UKDILAS), our specialist breastfeeding medicines advice service if you need support in the following situations:

• you need further advice
• the vaccine in question is not included here
• the infant might be immunosuppressed and a live vaccine is being considered
• yellow fever vaccine is required
• the infant is unwell or premature.

About our recommendations

Recommendations are based on published evidence where available. However, evidence is generally very poor and limited, and can require professional interpretation. Assessments are often based on reviewing case reports which can be conflicting and lack detail.

If there is no published clinical evidence, assessments are based on: pharmacodynamic and pharmacokinetic principles, extrapolation from similar drugs, risk assessment of normal clinical use, expert advice, and unpublished data. Simulated data are now increasingly being used due to the ethical difficulties around gathering good quality evidence in this area.

Bibliography

Full referencing is available on request.

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