Acellular pertussis vaccine given by accelerated schedule: response of preterm infants

Area of Science:

• Immunology
• Neonatal Medicine
• Vaccinology

Background:

• Preterm infants often exhibit altered immune responses compared to term infants.
• Vaccination schedules are critical for ensuring adequate protection in vulnerable populations.
• The impact of antenatal and postnatal steroid exposure on infant immunity requires further investigation.

Purpose of the Study:

• To evaluate the immune response of preterm infants to an accelerated diphtheria/tetanus/three component acellular pertussis (DTaP) vaccine schedule.
• To assess the influence of antenatal and postnatal steroid exposure on vaccine immunogenicity in preterm infants.
• To compare the immune responses of preterm infants with those of term infants.

Main Methods:

• A prospective observational study involving 130 preterm infants (mean gestational age 29.1 weeks) and 54 term infants.
• Administration of the DTaP-Haemophilus influenzae type b vaccine at 2, 3, and 4 months of age.
• Measurement of IgG geometric mean concentrations (GMC) to vaccine antigens via blood samples.

Main Results:

• Preterm infants had significantly lower IgG GMC to pertussis toxin (PT) compared to term infants after the third DTaP immunisation.
• Antibody responses to diphtheria, tetanus, filamentous haemagglutinin (FHA), and pertactin (PRN) were comparable between preterm and term infants.
• Higher gestational age at birth and older age at the third immunisation correlated with increased antibody responses to several vaccine antigens.

Conclusions:

• Preterm infants receiving an accelerated DTaP vaccination schedule exhibit a reduced IgG GMC to pertussis toxin.
• Immune responses to tetanus, FHA, and PRN are positively influenced by gestational age at birth and age at immunisation.
• Antenatal steroid exposure was associated with decreased anti-tetanus IgG levels, while postnatal steroids had no significant effect.