Pertussis Immunization Before 24 Weeks of Pregnancy: Maternal Antibody Transfer, Reactogenicity and Acceptance

Abstract

In this thesis, we describe several aspects of early maternal tetanus, diphtheria and acellular pertussis (Tdap) vaccination before 24 weeks of pregnancy in order to protect the infant against severe pertussis in the first months of life. Data from a longitudinal cohort study after maternal Tdap vaccination between 20-24 weeks of gestation were compared with a reference cohort after Tdap vaccination between 30-33 weeks of gestation. Pertussis-specific antibodies in term infants were compared with those of preterm infants, together with reactogenicity and acceptance of maternal Tdap vaccination before 24 weeks of gestation. The results indicate that vaccination before 24 weeks of gestation is suboptimal for transplacental antibody transfer and leads to two-fold lower antibody concentrations at the age of two months in term-born infants, compared with vaccination at 30-33 weeks. In early premature infants, i.e. born before 32 weeks of gestation, this may be up to 3-fold lower antibody levels, while in late-preterm infants, i.e. born after 32 weeks of gestation, similar antibody concentrations were found in preterm infants. The side reactogenicity and acceptance were unaffected by earlier administration of Tdap-vaccination during pregnancy. More research is needed to investigate whether the impared transfer may lead to a weaker protection against pertussis. Beside the results of the cohort study, this thesis also describes antibody transfer after maternal Tdap vaccination in pregnant women with chronic inflammatory diseases who use immune-modulating medication. Also, the pertussis incidence in the Caribbean part of the Netherlands was estimated based on a serosurveillance study from 2017, which implicates that up to 8% of adolescents were recently infected by Bordettella pertussis.