Maternal Immunization: New Perspectives on Its Application Against Non-Infectious Related Diseases in Newborns

Vaccines - safety in pregnancy

Vaccination during pregnancy is important for active immunity of the mother against serious infectious diseases, and also for passive immunity of the neonate to infectious diseases with high morbidity and mortality. As a rule, live vaccines are contraindicated during pregnancy as they may cause fetal viremia/bacteremia. Inactivated vaccines are generally safe. Vaccines safe to be administered to all pregnant ladies are tetanus toxoid (TT; tetanus, diphtheria, acellular pertussis (Tdap) and Flu vaccines. During pre-pregnancy counselling, vaccination for MMR (measles, mumps, and rubella) should be offered, with an advice to avoid pregnancy for a month. All pregnant mothers should receive TT and Tdap vaccination during the third trimester. Flu vaccine can be given to all mothers at any gestation, and if not offered during pregnancy, it can be given postpartum. Vaccinations that should be offered to women if at high risk of exposure are for hepatitis A and B, pneumococcal, meningococcal, yellow fever, Japanese encephalitis (JE), polio, typhoid, and cholera infections. Vaccines to be given only for post-exposure prophylaxis (PEP) are smallpox, rabies, and anthrax. Postpartum women should be offered human papillomavirus (HPV) vaccination. If not immunized earlier, they should be offered MMR, Tdap, and Flu vaccines. Future vaccines being developed are for malaria, Zika virus, respiratory syncytial virus (RSV), group B streptococcus, CMV, and COVID-19 (SARS-Cov-2).

Closer and closer? Maternal immunization: current promise, future horizons

This state-of-the art manuscript highlights our current understanding of maternal immunization-the practice of vaccinating pregnant women to confer protection on them as well as on their young infants, and thereby reduce vaccine-preventable morbidity and mortality. Advances in our understanding of the immunologic processes that undergird a normal pregnancy, studies from vaccines currently available and recommended for pregnant women, and vaccines for administration in special situations are beginning to build the case for safe scale-up of maternal immunization. In addition to well-known diseases, new diseases are emerging which pose threats. Several new vaccines are currently under development and increasingly include pregnant women. In this manuscript, targeted at clinicians, vaccinologists, scientists, public health practitioners, and policymakers, we also outline key considerations around maternal immunization introduction and delivery, discuss noninfectious horizons for maternal immunization, and provide a framework for the clinician faced with immunizing a pregnant woman.

Maternal Immunization Confers Protection to the Offspring against an Attaching and Effacing Pathogen through Delivery of IgG in Breast Milk

Owing to immature immune systems and impaired colonization resistance mediated by the microbiota, infants are more susceptible to enteric infections. Maternal antibodies can provide immunity, with maternal vaccination offering a protective strategy. We find that oral infection of adult females with the enteric pathogen Citrobacter rodentium protects dams and offspring against oral challenge. Parenteral immunization of dams with heat-inactivated C. rodentium reduces pathogen loads and mortality in offspring but not mothers. IgG, but not IgA or IgM, transferred through breast milk to the intestinal lumen of suckling offspring, coats the pathogen and reduces intestinal colonization. Protective IgG largely recognizes virulence factors encoded within the locus of enterocyte effacement (LEE) pathogenicity island, including the adhesin Intimin and T3SS filament EspA, which are major antigens conferring protection. Thus, pathogen-specific IgG in breast milk induced during maternal infection or immunization protects neonates against infection with an attaching and effacing pathogen.

Maternal Vaccination as an Essential Component of Life-Course Immunization and Its Contribution to Preventive Neonatology

Maternal immunisation schedules are increasingly coming under the spotlight as part of the development of lifetime immunisation programmes for the role that they play in improving maternal, foetal, and neonatal health. Maternally-acquired antibodies are critical in protecting infants during the first months of their lives. Maternal immunisation was previously overlooked owing to concerns regarding vaccinations in this untested and high-risk population but is now acknowledged for its potential impact on the outcomes in many domains of foetal and neonatal health, aside from its maternal benefits. This article highlights the role that maternal immunisation may play in reducing infections in preterm and term infants. It explores the barriers to antenatal vaccinations and the optimisation of the immunisation uptake. This review also probes the part that maternal immunisation may hold in the reduction of perinatal antimicrobial resistance and the prevention of non-infectious diseases. Both healthcare providers and expectant mothers should continue to be educated on the importance and safety of the appropriate immunizations during pregnancy. Maternal vaccination merits its deserved priority in a life-course immunization approach and it is perhaps the only immunization whereby two generations benefit directly from a single input. We outline the current recommendations for antenatal vaccinations and highlight the potential advances in the field contributing to “preventive neonatology”.