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Three-year follow-up of vaccine response in extremely preterm infants
R Khalak1, M E Pichichero, C T D'Angio
1Department of Pediatrics, Neonatology, Strong Children's Research Center, Rochester, New York 14642, USA.
Insights
Antibody responses in extremely premature infants were generally sustained after booster vaccines, though some differences were noted. Preterm children showed lower antibody levels for Haemophilus influenzae type b and polio serotype 3 compared to full-term peers.
Area of Science:
- Immunology
- Pediatrics
- Vaccinology
Background:
- Extremely premature infants (<29 weeks gestation) often exhibit altered immune responses.
- Previous studies indicated adequate antibody responses after primary immunization series in former extremely premature infants.
- The persistence of these responses after booster vaccinations in this vulnerable population requires further investigation.
Purpose of the Study:
- To evaluate the sustained antibody response in former extremely premature infants after receiving their first booster vaccines.
- To compare antibody titers between former extremely premature and full-term infants at 3 to 4 years of age.
- To assess immune memory and protection levels against key vaccine-preventable diseases.
Main Methods:
- A cohort study involving 16 former extremely premature (<29 weeks) and 17 former full-term (>37 weeks) infants.
- Sera were collected at 3 to 4 years of age for antibody titer measurement.
- All participants received primary series and first booster vaccines for diphtheria, pertussis, tetanus, polio, and Haemophilus influenzae type b (Hib); some also received hepatitis B vaccine.
Main Results:
- Similar geometric mean titers (GMTs) for tetanus, diphtheria, and pertussis antibodies were observed in both groups.
- Former preterm infants had significantly lower GMTs for Haemophilus polyribosylribitol phosphate (PRP) antibodies compared to full-term infants.
- While most children achieved protective antibody levels for polio serotypes 1 and 2, and hepatitis B, responses to Hib (PRP) and polio serotype 3 were less robust in the preterm group.
Conclusions:
- Preterm infants immunized at recommended chronological ages generally maintain adequate antibody responses for most antigens.
- However, immune responses to Haemophilus influenzae type b (PRP) and polio serotype 3 appear less robust in former extremely premature infants compared to their full-term counterparts.
- These findings highlight the need for continued monitoring of vaccine efficacy in preterm populations.
Objective:
To assess whether the adequate antibody response observed in former extremely premature infants after the primary series of immunizations is sustained after the first booster vaccines.
Subjects And Methods:
Sixteen former extremely premature (<29 weeks, <1000 g at birth) and 17 former full-term (>37 weeks) infants had sera obtained for antibody titer measurement at 3 to 4 years of age. All had received the primary series and first booster vaccines for diphtheria, pertussis, tetanus, polio, and Haemophilus influenzae type b. Twelve preterm and 14 full-term children had completed the hepatitis B vaccine series.
Results:
At 3 to 4 years of age, former preterm and full-term children had similar geometric mean titer (GMT) values of antibodies to tetanus, diphtheria, and pertussis. Preterm children had a lower GMT value of Haemophilus polyribosylribitol phosphate (PRP) antibody than did full-term children (0.99 vs 3.06 microg/mL). Fifty percent of preterm and 88% of full-term children had PRP antibody >1.0 microg/mL; 100% of preterm and 94% of full-term children had anti-PRP titers >0.15 microg/mL. GMT values of neutralizing antibodies to polio serotypes 1 and 2 were similar, with 94% to 100% of both groups above protective levels (>/=1:8). The difference in GMT values of polio serotype 3 approached significance (29 vs 73); fewer preterm children had protective titer values (75% vs 100%). Among children vaccinated against hepatitis B, 75% of preterm and 71% of full-term children were protected (10 mIU/mL).
Conclusions:
Preterm children immunized at the recommended chronological ages displayed antibody responses similar to those for full-term children for most immunizing antigens. Responses to PRP and polio serotype 3 were less robust than those of full-term children.