This is a very useful discussion on this important subject that was put on the Travel Medicine Discussion List for members of International Society of Travel Medicine.
TravelSafe Clinic is the ONLY member of this International Travel Health Organization in North India.
Here is the post
" YF vaccination of a breastfeeding woman came up recently in our practice. I ended up consulting with the folks at CDC. The response:
There are many gaps in our knowledge of the risk for potential YF vaccine exposure through breastfeeding. What we do know is that viremia after first time YF vaccination occurs in healthy patients, and has been demonstrated by studies to disappear by day 10 post vaccination. We also know that there have been 3 recent cases reported of encephalitis (with laboratory evidence of causality by the YF vaccine virus) in 3 exclusively breastfed infants whose mothers were vaccinated with YF vaccine. All 3 infants were less than 1 month of age at the time of exposure. However , the precise mechanism of the transmission of YF vaccine virus to the infants has not been established. Potential mechanisms are transmission through breast milk or direct blood-to-blood transmission involving excoriated maternal nipple and infant oral mucosa.
There have been no published studies on whether YF vaccine virus is excreted in breast milk. Therefore, any recommendations on the time after maternal vaccination at which the breast milk should be free from any potentially excreted YF vaccine virus are speculative and indirectly based on what we know about the duration of virus in the blood of healthy vaccinated persons. The ACIP (Advisory Committee on Immunization Practices) recommends that YF vaccine be avoided in breastfeeding women, but that if the mother’s travel to a YF endemic area cannot be avoided or postponed, these women should be vaccinated. If this situation does occur, a reasonable (and not evidence-based) recommendation would be for the mother to pump and discard her breast milk for at least 14 days after vaccination, before resuming breastfeeding (to provide some margin of safety beyond the potential 10th day post vaccination during which she could have YF vaccine virus in her blood).
Although YF vaccine is indicated for infants at least 9 months of age (travelling to YF endemic areas), this recommendation is based on subcutaneous injection as the recommended route of exposure. Although clinicians make assumptions, based on extrapolation, that potential exposure of an infant at least 9 months of age to YF vaccine virus through breastfeeding should therefore be safe, this is unproven, and theoretically might not be the case. The amount of YF vaccine virus that an infant might be exposed to, and it’s potential for replication in the infant’s bloodstream, might be different if the route of exposure is direct blood to blood (excoriated maternal nipple and excoriated infant oral mucosa). However, such a risk is probably very low, given the small number of reports of YF vaccine-associated encephalitis in breast fed infants, and only in infants of very young age.
The safest scenario would be one in which the breastfeeding infant/child is at least 9 months of age and also needing YF vaccination because of unavoidable travel to a YF endemic country. If the infant/child were vaccinated against YF first, then they would be expected to have developed protective antibodies against YF vaccine by 10 days after vaccination. If the mother were then vaccinated against YF (at least 10 days after the infant/child), the infant could safely breasted, as they should then be immune to YF virus and be protected against exposure to any YF virus potentially excreted in breast milk or transmitted by an alternate route in breastfeeding (described above). In this scenario, if the mother pumped and discarded her breast milk for 14 days after vaccination, this would add even more to the margin of safety."
TravelSafe Clinic is the ONLY member of this International Travel Health Organization in North India.
Here is the post
" YF vaccination of a breastfeeding woman came up recently in our practice. I ended up consulting with the folks at CDC. The response:
There are many gaps in our knowledge of the risk for potential YF vaccine exposure through breastfeeding. What we do know is that viremia after first time YF vaccination occurs in healthy patients, and has been demonstrated by studies to disappear by day 10 post vaccination. We also know that there have been 3 recent cases reported of encephalitis (with laboratory evidence of causality by the YF vaccine virus) in 3 exclusively breastfed infants whose mothers were vaccinated with YF vaccine. All 3 infants were less than 1 month of age at the time of exposure. However , the precise mechanism of the transmission of YF vaccine virus to the infants has not been established. Potential mechanisms are transmission through breast milk or direct blood-to-blood transmission involving excoriated maternal nipple and infant oral mucosa.
There have been no published studies on whether YF vaccine virus is excreted in breast milk. Therefore, any recommendations on the time after maternal vaccination at which the breast milk should be free from any potentially excreted YF vaccine virus are speculative and indirectly based on what we know about the duration of virus in the blood of healthy vaccinated persons. The ACIP (Advisory Committee on Immunization Practices) recommends that YF vaccine be avoided in breastfeeding women, but that if the mother’s travel to a YF endemic area cannot be avoided or postponed, these women should be vaccinated. If this situation does occur, a reasonable (and not evidence-based) recommendation would be for the mother to pump and discard her breast milk for at least 14 days after vaccination, before resuming breastfeeding (to provide some margin of safety beyond the potential 10th day post vaccination during which she could have YF vaccine virus in her blood).
Although YF vaccine is indicated for infants at least 9 months of age (travelling to YF endemic areas), this recommendation is based on subcutaneous injection as the recommended route of exposure. Although clinicians make assumptions, based on extrapolation, that potential exposure of an infant at least 9 months of age to YF vaccine virus through breastfeeding should therefore be safe, this is unproven, and theoretically might not be the case. The amount of YF vaccine virus that an infant might be exposed to, and it’s potential for replication in the infant’s bloodstream, might be different if the route of exposure is direct blood to blood (excoriated maternal nipple and excoriated infant oral mucosa). However, such a risk is probably very low, given the small number of reports of YF vaccine-associated encephalitis in breast fed infants, and only in infants of very young age.
The safest scenario would be one in which the breastfeeding infant/child is at least 9 months of age and also needing YF vaccination because of unavoidable travel to a YF endemic country. If the infant/child were vaccinated against YF first, then they would be expected to have developed protective antibodies against YF vaccine by 10 days after vaccination. If the mother were then vaccinated against YF (at least 10 days after the infant/child), the infant could safely breasted, as they should then be immune to YF virus and be protected against exposure to any YF virus potentially excreted in breast milk or transmitted by an alternate route in breastfeeding (described above). In this scenario, if the mother pumped and discarded her breast milk for 14 days after vaccination, this would add even more to the margin of safety."
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