Immunogenicity of a liquid hexavalent DTaP-IPV-HB-PRP~T vaccine after primary and booster vaccination of term and preterm infants born to women vaccinated with Tdap during pregnancy

Multivalent pediatric combination vaccines like DTaP-IPV-HB-PRP~T are important to protect children against various diseases. Infants born preterm are at high risk of serious pertussis disease in the first month of life. Before they are protected by their own immunization, vaccination with tetanus, diphtheria, and acellular pertussis (Tdap) during pregnancy is important for early protection of infants against pertussis, especially for preterm infants. A prospective, observational study was conducted to evaluate the immunogenicity of the DTaP-IPV-HB-PRP~T vaccine in term and preterm infants born to Tdap-vaccinated women.

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Background

Vaccination during pregnancy with tetanus, diphtheria, acellular pertussis (aP) (Tdap) antigens is important for early protection of newborn infants against pertussis, particularly for preterm infants. This study evaluated the effect of Tdap vaccination during pregnancy on the immunogenicity of a diphtheria (D), tetanus (T), aP, inactivated poliovirus (IPV), hepatitis B (HB), and Haemophilus influenza type b (PRP ~ T) vaccine in term and preterm populations

Methods

A prospective, observational study (NCT02511327) recruited women and their infants based on delivery (term or preterm) and vaccination status (vaccinated with a Tdap vaccine [BoostrixTM, GlaxoSmithKline] during pregnancy or not vaccinated in the last 5 years). All infants received licensed DTaP-IPV-HB-PRP ~ T (HexyonTM, Sanofi) (8, 12, 16 week primary series and booster at 13 months of age [preterm infants] or 15 months of age [term infants]). Immunogenicity was evaluated using validated assays. Data were pooled into term (N = 127) and preterm infants (N = 105), and infants of women who received a Tdap vaccine during pregnancy (N = 199) or not (N = 33).

Results

Before primary vaccination, antibody levels were higher for term than preterm infants for anti-D, anti-polio 1, 2, 3, anti-PT, anti-FHA, and anti-PRP, and similar for anti-HBs and anti-T. At this time, infants of Tdap-vaccinated women had higher anti-D, anti-T, anti-PT, anti-FHA, and anti-PRP antibody levels than infants of Tdap-unvaccinated women; anti-HBs and anti-polio antibody levels were similar in both groups. Post-primary, pre-booster, and post-booster, there were only small differences in seroprotection rates (anti-D, anti-T, anti-polio 1, 2, 3, anti-HBs, anti-PRP) and seroconversion rates (anti-PT, anti-FHA), except for anti-HBs ≥ 10 mIU/mL and anti-PRP ≥ 0.15 lg/mL post-primary vaccination (higher for term [98.31 % and 90.91 %, respectively] versus preterm infants [89.80 % and 79.41 %, respectively]).

Conclusion

These data support the use of DTaP-IPV-HB-PRP T vaccine for primary and booster vaccination in term and preterm born infants and in infants born to Tdap-vaccinated or Tdap-unvaccinated women.

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