Table 1.

Global Pertussis Initiative Statement on Vaccination Against Pertussis in Pregnancy.

Safety and Vaccine Effectiveness
Vaccination against pertussis in pregnancy is safe for pregnant women and newborns and highly effective in preventing pertussis in young term and preterm infants.
Timing of vaccination
Vaccination against pertussis in the third trimester of pregnancy is highly effective in the prevention of pertussis in both term and preterm infants.
A growing body of evidence supports that vaccination early in the third trimester is associated with higher newborn anti-B. pertussis antibody concentrations compared with vaccination in the late third trimester. More data are required to confirm this observation and whether vaccination early in the third trimester is associated with higher vaccine effectiveness compared to later in the third trimester.
More studies are needed to determine whether vaccination in the second trimester is associated with higher newborn anti-B. pertussis antibody concentrations and vaccine effectiveness compared with vaccination in third trimester of pregnancy.
There is currently no evidence to suggest that timing of vaccination in pregnancy affects post-primary and post-booster vaccination antibody concentrations in infants, although more formal studies designed to answer this question are needed.
Vaccination against pertussis at any time during pregnancy is still important to ensure protection of infants against pertussis.
Modification of an infant’s immune responses
The term “modification” or “modulation” describes the overall effect of vaccination in pregnancy on overall antibody responses in infants, and the term “interference” describes a specific decrease in antigen-specific antibody responses in infants of vaccinated mothers.
A significant body of literature supports that (A) infants of vaccinated women have less boosting of anti-B pertussis antibody concentrations after their own vaccination and (B) this is not clinically significant in countries using aP vaccines for primary and booster vaccination. More immunogenicity and vaccine effectiveness studies are needed in countries using wP vaccines, although current literature does not show this to be of clinical relevance (at this time).
Infants of vaccinated women have lower anti-Streptococcus pneumoniae IgG concentrations after vaccination with pneumococcal vaccines conjugated with CRM197, but the clinical significance needs to be investigated. Formal studies to answer this question are needed.
Infants of vaccinated women have higher anti-TT concentrations compared with infants of unvaccinated women, which is not adequately described by “interference” or “blunting”.
The mechanism of modification of immune responses in infants needs to be investigated, although it is likely to be mediated, at least in part, by high maternal antibody concentrations.
In utero exposure to vaccine antigens
Recent literature supports that there might be an exposure to vaccine antigens in utero as evident by B. pertussis–specific cellular immune response in infants of vaccinated women prior to receipt of any of the infant’s vaccine doses. The clinical significance of this is unclear.
Non-specific effects following vaccination against pertussis in pregnancy have not been studied and should be addressed by future research.
Anti-B. pertussis antibodies in breast milk
Vaccination in pregnancy induces anti-B. pertussis antibodies in breast milk until 12 weeks post-partum. The added benefit of breastfeeding in infants of vaccinated women to clinical protection is unclear.
Effect of COVID-19 on pertussis
COVID-19 mitigation strategies have resulted in a significant decrease in B. pertussis circulation, which could affect population immunity against B. pertussis. Continued enhanced surveillance during COVID-19 and emphasis on continued vaccination is needed.