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

Abstract

Background: Biological agents cross the placenta, resulting in detectable blood levels in the neonate. Neonatal vaccinations are essential to prevent serious infections. Aim: To review the effectiveness and safety of vaccines in children exposed to biological drugs in utero and/or those whose mothers received biological agents during lactation. Methods: A systematic bibliographic search was performed. Results: Infants exposed in utero to anti-tumour necrosis factor drugs [anti-TNFs], vedolizumab or ustekinumab mount adequate serological responses to vaccines. No relevant adverse events for non-live inactivated vaccines have been reported in newborns exposed in utero to biologics. Studies assessing the safety of live-attenuated vaccines administered to infants exposed to biologics in utero have not observed, in general, serious adverse events. However, although no severe complications have been reported with rotavirus live vaccination, several fatal disseminated tuberculosis infections after administration of the BCG live vaccine in infants exposed to anti-TNFs in utero have been reported. Infliximab, adalimumab, and probably also vedolizumab and ustekinumab treatments are considered compatible with breastfeeding, although minuscule amounts of these biologics have been detected in breast milk of treated nursing mothers. Based on the literature available, the benefits from breastfeeding while receiving infliximab [or any other anti-TNF] and at the same time adhering to national infant immunization programmes probably outweigh any hypothetical risk for the infant. Conclusions: Vaccines appear to be effective in infants exposed to biologics in utero. Inactivated vaccines are probably safe, whereas live-attenuated vaccines should be avoided while the children have detectable levels of biological drugs. Vaccines [non-live and live] are probably safe in children breastfed by mothers treated with biologics.