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Interplay between Tetanus, Diphtheria, Acellular Pertussis Vaccination in Pregnancy and Infant Pneumococcal
Eline Van den Bosch1, Helene Vermeulen2, Esra Ekinci1
1Centre for the Evaluation of Vaccination, University of Antwerp, Wilrijk, Belgium.
Insights
Maternal Tetanus, Diphtheria and acellular Pertussis (Tdap) vaccination during pregnancy was linked to higher pneumococcal vaccine-related serotype carriage in infants. Further research is needed to understand the clinical significance of this finding.
Area of Science:
- Immunology
- Vaccinology
- Pediatric Infectious Diseases
Background:
- Tetanus, Diphtheria and acellular Pertussis (Tdap) vaccination in pregnancy may impact infant immune responses to pneumococcal conjugate vaccines (PCVs).
- The effect of maternal Tdap vaccination on infant nasopharyngeal carriage of pneumococcal vaccine serotypes is not well understood.
Purpose of the Study:
- To investigate the association between maternal Tdap vaccination during pregnancy and pneumococcal vaccine-related serotype carriage in infants.
- To analyze the impact of different pneumococcal conjugate vaccine schedules on serotype carriage.
Main Methods:
- Collection of 3,298 nasopharyngeal swabs from infants aged 6-30 months in Belgium (2018-2022).
- Assessment of Streptococcus pneumoniae carriage and serotyping using culture-based (Quellung reaction) and molecular methods (qPCR).
- Logistic generalized estimating equation models used to evaluate the association between maternal Tdap vaccination and infant pneumococcal serotype carriage.
Main Results:
- Infants born to mothers vaccinated with Tdap during pregnancy exhibited significantly higher PCV13-related serotype carriage.
- Infants receiving PCV10 or mixed PCV10/PCV13 schedules showed increased PCV13-related serotype carriage compared to PCV13-only recipients.
- A significant increase in carriage of serotype 6C was observed in infants of Tdap-vaccinated mothers; no difference in non-vaccine serotype carriage was found.
Conclusions:
- Maternal Tdap vaccination during pregnancy is associated with elevated pneumococcal vaccine-related serotype carriage in infants.
- The clinical implications of this increased carriage require further investigation.
- Future studies should correlate vaccine serotype carriage with antibody levels to guide maternal and infant vaccination strategies.
Background:
Tetanus, diphtheria and acellular pertussis (Tdap) vaccination during pregnancy blunts the infant humoral immune response following primary immunization with pneumococcal conjugate vaccines (PCVs). While this effect typically resolves after the booster dose for most vaccine serotypes, its impact on nasopharyngeal carriage of pneumococcal vaccine serotypes remains unclear.
Methods:
A total of 3298 nasopharyngeal swabs were collected from infants aged 6-30 months attending daycare centers in Belgium between 2018 and 2022, along with data on maternal Tdap vaccination status (clinicaltrials.gov identifier: NCT02888457). Streptococcus pneumoniae carriage and serotyping were assessed using culture-based methods (Quellung reaction) and molecular detection (LytA qPCR and serotype-specific qPCR). The association between Tdap vaccination during pregnancy and pneumococcal vaccine-related serotype carriage in infants was evaluated using logistic generalized estimating equation models.
Results:
The PCV13-related serotype carriage was significantly higher in offspring of Tdap-vaccinated mothers during pregnancy compared to those born to Tdap-unvaccinated mothers. In addition, children who received a PCV10 or mixed PCV10/PCV13 schedule had significantly higher PCV13-related serotype carriage compared to those immunized exclusively with PCV13. No significant differences were observed in individual PCV13-related serotype carriage, except for a significantly higher carriage of the PCV13-related serotype 6C in children of Tdap-vaccinated mothers. No significant difference was found for non-vaccine serotype carriage.
Conclusions:
The Tdap vaccination during pregnancy was associated with increased pneumococcal vaccine-related serotype carriage in infants, though the clinical significance remains uncertain. Future studies integrating vaccine serotype carriage data with protective pneumococcal antibody levels are needed to inform future maternal and infant vaccination strategies.
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