Are the Vaccines Effective and Safe in Children Exposed to Biological Agents In Utero and/or During Breastfeeding?

Biological agents can cross the placenta and result in detectable blood levels in the neonate. Neonatal vaccinations are crucial to prevent serious infections.

 Gisbert JP and Chaparro M reviewed the effectiveness and safety of vaccines in children exposed to biological drugs in utero and/or those whose mothers used biological agents during lactation.

They found that infants exposed in utero to anti-tumor necrosis factor drugs [anti-TNFs], vedolizumab, or ustekinumab give adequate serological responses to vaccines. They also found no relevant adverse events for non-live inactivated vaccines in newborns exposed in utero to biologics. Furthermore, the studies that assessed the safety of live-attenuated vaccines administered to infants exposed to biologics in utero didn't observe serious adverse events in general. 

The researchers found no reports of severe complications with rotavirus live vaccination, but they found several fatal disseminated tuberculosis infections after administration of the BCG live vaccine in infants exposed to anti-TNFs in utero. They found Infliximab, adalimumab, and probably also vedolizumab and ustekinumab treatments to be compatible with breastfeeding; however, their small amounts can be traced in the breast milk of treated nursing mothers. Based on the available literature, breastfeeding benefits while receiving Infliximab [or any other anti-TNF] and adhering to national infant immunization programs outweigh any potential risk for the infant.

Hence it is confirmed that vaccines are effective in infants exposed to biologics in utero. Inactivated vaccines are safe, whereas live-attenuated vaccines should be avoided when the children have detectable levels of biological drugs. Vaccines [non-live and live] are probably safe in children of lactating mothers receiving biologics.

Gisbert JP, Chaparro M. Vaccines in Children Exposed to Biological Agents In Utero and/or During Breastfeeding: Are They Effective and Safe?. Journal of Crohn's and Colitis. 2023: jjad005. https://doi.org/10.1093/ecco-jcc/jjad005