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Assessing Respiratory Immune Responses to Haemophilus Influenzae
06:32

Assessing Respiratory Immune Responses to Haemophilus Influenzae

Published on: June 29, 2021

Long-term persistence of immunity after immunisation with Haemophilus influenzae type b conjugate vaccine

P Helena Mäkelä1, Helena Käyhty, Tuija Leino

  • 1National Public Health Institute, Mannerheimintie 166, FIN-00300, Helsinki, Finland.

Vaccine
|November 15, 2003
PubMed

Insights

Children vaccinated with Haemophilus influenzae type b (Hib) conjugate vaccines in infancy retain immunological memory years later. This suggests long-lasting protection against Hib infections, even with intervening bacterial exposures.

Area of Science:

  • Immunology
  • Vaccinology
  • Pediatrics

Background:

  • Haemophilus influenzae type b (Hib) conjugate vaccines are widely recommended but their long-term protective immunity duration is unknown.
  • Assessing immune response in children years after primary vaccination is crucial for understanding vaccine efficacy.

Purpose of the Study:

  • To evaluate the immunogenicity and duration of protective immunity conferred by Haemophilus influenzae type b (Hib) conjugate vaccines.
  • To compare antibody concentrations and immune memory in children vaccinated with Hib conjugate vaccines versus control groups.

Main Methods:

  • Studied 37 children vaccinated with Hib conjugate vaccine (PRP-D) in infancy, comparing them to 37 unvaccinated controls and 13 children who received Hib polysaccharide vaccine.
  • Measured anti-Hib polysaccharide antibodies (Hib-ab) before and after a booster dose of Hib polysaccharide vaccine.
  • Analyzed antibody concentrations, IgG proportion, and antibody avidity.

Main Results:

  • Children vaccinated with Hib conjugate vaccines had 3.6-fold higher Hib-ab concentrations pre-booster compared to controls.
  • Post-booster, the Hib conjugate group showed higher total Hib-ab, increased IgG proportion, and greater antibody avidity.
  • Mathematical modeling supported the persistence of immunological memory, maintained by anamnestic responses.

Conclusions:

  • Infant vaccination with Hib conjugate vaccines establishes durable immunological memory.
  • This persistent memory suggests long-term protection against Haemophilus influenzae type b, potentially sustained by responses to other bacterial stimuli.

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