The meningococcal group B vaccine 4CMenB is a new, recombinant protein-based vaccine that is licensed to protect against invasive group B meningococcal disease. However, its role in preventing transmission and, therefore, inducing population (herd) protection is uncertain.

OBJECTIVE: To assess antenatal, birth, and infant outcomes for pregnant women, fetuses, and infants after antenatal vaccination with any antigen present in combination pertussis vaccines. DATA SOURCES: PubMed, EMBASE, Literature in the Health Sciences in Latin America and the Caribbean, ClinicalTrials.gov, Cochrane Library, and World Health Organization (inception to May 5, 2016). METHODS OF STUDY SELECTION: Studies reporting outcomes for pregnant women, their fetus, or infant after antenatal exposure to either monovalent or combined tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) or inactivated polio vaccines were considered for inclusion. RESULTS: A total of 21 studies were included in this review. Point estimates ranged from 0.47 to 1.50 for preterm birth (less than 37 weeks of gestation), 0.65–1.00 for small for gestational age (birth weight less than the 10th percentile), 0.36–0.85 for stillbirth, 0.16–1.00 for neonatal death, 0.76–1.20 for low birth weight (less than 2,500 g), and 0.20–0.91 for congenital anomalies. All lower 95% confidence intervals (CIs) were less than 1.0. Of three retrospective studies assessing chorioamnionitis after vaccination, one showed a small but statistically significant increase. Point estimates for all anomalies after antenatal tetanus toxoid vaccination ranged from 1.20 to 1.60 and had 95% CIs that crossed 1.0. There was substantial clinical and methodologic heterogeneity from mainly retrospective observational studies with an overall high risk of bias. Objective rates of fever were low, 3% or below, and more common systemic events observed included headache, malaise, and myalgia. CONCLUSION: Evidence suggests that antenatal combined Tdap administered during the second or third trimester of pregnancy is not associated with clinically significant harms for the fetus or neonate. Medically attended events in pregnant women are similar between vaccinated and unvaccinated groups.

Maternal immunization has the potential to reduce the burden of infectious diseases in the pregnant woman and her infant. Many countries now recommend immunization against influenza at any stage of pregnancy and against pertussis in the third trimester. Despite evidence of the safety and effectiveness of these vaccines when administered during pregnancy, uptake generally remains low for influenza and moderate for pertussis vaccine. Enhancing confidence in both immunization providers and pregnant women by increasing the evidence-base for the safety and effectiveness of vaccines during pregnancy, improving communication and access by incorporating immunization into standard models of antenatal care are likely to improve uptake. Developing a framework for implementation of vaccines for pregnant women which is cognizant of local and national cultural, epidemiological, behavioral and societal factors will enable a smooth transition and high uptake for new vaccines currently in development for pregnant women.