Timing of maternal Tdap vaccination: A dynamic balance between antibody induction and placental transfer efficiency
In brief
Later pregnancy Tdap shots raise maternal antibody levels but leave newborn protection unchanged
In a study of 96 women vaccinated between weeks 16 and 32, those who received Tdap later in gestation had higher maternal IgG1 levels at delivery, yet cord blood antibody amounts and functional transfer were similar across all timing groups. The results support the current 16-32-week window, showing flexibility without compromising infant immunity.
- Journal
- Vaccine (Q1)
- Published
- 18 July 2026
- Study design
- Randomized controlled trial
- Evidence level
- Level 1, High (CEBM 1b)
- Authors
- Louise De Weerdt, Anaïs Thiriard, Inès Vu Duc, Nina Reviya, Pierre Van Damme, Niel Hens, et al.
- PMID
- 42472495
- DOI
- 10.1016/j.vaccine.2026.128953
Why clinicians should know about it
- Picked for Immunology and Allergy (paper of the day, 20 July 2026).
- Picked for Infectious Diseases (paper of the day, 20 July 2026).
- Picked for Pediatrics and Child Health (paper of the day, 20 July 2026): Timing of maternal Tdap vaccination, impacts neonatal immunity
Abstract
BACKGROUND: Tetanus, diphtheria, acellular pertussis (Tdap) vaccination in pregnancy protects newborns against pertussis, but the influence of gestational age (GA) at vaccination on maternal and neonatal immune profiles remains incompletely understood. This study aimed to characterize the effect of GA at Tdap vaccination on several antibody features during pregnancy and at birth, and to assess transplacental antibody transfer. METHODS: 96 pregnant women received Tdap at different GAs between week 16 and 32 within a Belgian, prospective non-randomized controlled trial. Maternal blood was collected pre-vaccination, at multiple timepoints post-vaccination, and at delivery, alongside cord blood at birth. Tdap-specific total IgG and IgG subclasses were evaluated alongside Fc-mediated effector functions. Multivariate analyses were applied to define composite immune patterns. RESULTS: Post-vaccination, robust immune responses were observed across cohorts. At delivery, maternal total IgG and IgG1 against PRN, DT, and TT were higher with later vaccination, whereas other subclasses and functional responses were largely comparable. Cord blood profiles partially paralleled maternal patterns without reaching significance, and no significant effect of vaccination-to-delivery interval was detected. IgG transfer ratios generally declined with advancing GA; functional antibody transfer was largely unaffected. Multivariate analyses highlighted higher maternal antibody response profiles at delivery with later vaccination, while cord blood profiles were generally unaffected. CONCLUSION: Maternal Tdap antibody response profiles at delivery are influenced by vaccination timing, while neonatal antibody profiles at birth appear largely comparable within the limits of the study. These findings support current recommendations for Tdap administration between 16 and 32 weeks of gestation and underscore the flexibility of this window for routine antenatal care.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.