Researchers carried out a large-scale population-based cohort study across Australia to investigate maternal vaccination effectiveness (VE) against pertussis. They further evaluated whether the vaccination of a mother ≥14 days before the birth of her child would significantly alter the effectiveness of routine primary pertussis vaccine administration to the infant. Their results highlight that maternal vaccination reduced overall infection risk in infants and conferred pertussis resistance until eight months of age. While slightly lowering the VE of routine pertussis administered to infants, maternal pertussis was not associated with increased disease risk in infants.
Study
In the present study, researchers had two main objectives – 1. To estimate the infant VE of maternal vaccine administration on three scales (overall, by gestational age, and by infant age), and 2. Using real-world data to evaluate the potential 'blunting' effects that maternal vaccination would have on routine pediatric dTpa care. The study comprised data from the Links2HealthierBubs cohort, a population-based cohort of mother-infant pairs from the Northern Territory (NT), Western Australia (WA), and Queensland (QLD). All dyads wherein the gestational age was 20 weeks or greater or the infant was born weighing more than 400 g were included in this study.
Demographic and clinical data comprising perinatal birth, hospitalization, immunization, birth and death register, and disease data were collected from all participants. Mothers were recommended to receive maternal vaccination with dTpa between 28 and 32 weeks of gestation. Vaccination and maternal medication data were obtained from perinatal data collections, statutorily mandated databases archived at each jurisdiction. Hospital records were used to evaluate pertussis severity, and death records were used as proxies for infant mortality.
Statistical analyses comprised descriptive statistics using Chi-squared (χ2) tests (categorical variables) and Wilcoxon rank sum (continuous variables). A mixed effects Cox model was used to compare infection rates between infants whose mothers had received maternal vaccination versus those that had not.
Vaccine effectiveness (VE) was estimated by subtracting the hazard ratio (HR) of the weighted inverse probability of treatment (obtained from the Cox model) from one. For NT and QLD cohorts, models were fit to estimate the effects of maternal vaccination on subsequent routine dTpa infant vaccination (termed "blunting").
Results
The inclusion criteria listed above resulted in a sample cohort of 297,418 infants born to 252,444 mothers. Of these, 144,429 infants' mothers (51.7%) received maternal vaccination. Vaccination registration revealed that 14,028 (5%) received maternal vaccination before 28 weeks of gestation, 80,327 (28.7%) at 28-31 weeks, and 48,629 (17.4%) after 31 weeks but before birth.
VE model evaluations highlight that maternal vaccination conferred significantly higher pertussis resistance in infants compared to only routine vaccination. Maternal vaccination was found to persist till at least 8 months of age, more than 2 months longer than reported in previous studies. Immunological gestation time analysis found that contrasting previous work, which reported higher antibody titers (and hence, potentially better resistance) in cord blood of infants whose mothers were vaccinated closer to delivery, this study did not find differences in conferred resistance when adjusting for VE by the timing of delivery.
In infants under the influence of maternal vaccination, slight reductions in routine dTpa VE were observed. However, these reductions did not translate to reductions in pertussis resistance.
Conclusion
The present study aimed to evaluate the benefits of maternal vaccination during gestation as a means to combat pertussis during the early months of an infant's life. Findings from a large cohort Australian sample group revealed that maternal vaccination confers significantly improved infant resistance against the disease, with effects persisting for at least eight months. This study also reveals that, while slightly lowering the effectiveness of subsequent routine dTpa vaccinations in infants, maternal vaccination does not result in increased infection risk in infants.
Overall, these findings highlight the pros of maternal vaccination as a low-risk, high-reward weapon in humanity's arsenal against pertussis, one of the more severe and deadly diseases in infants and young children. These findings could help policymakers, inform prospective parents, and form the basis for future studies aimed at determining the optimal time and dosage of maternal vaccination for the best possible clinical outcomes in infants.
Source:
https://www.news-medical.net/news/20231011/Maternal-pertussis-vaccination-boosts-infant-protection-up-to-eight-months.aspx