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Seven-year follow-up of vaccine response in extremely premature infants
Khaver I Kirmani1, Geraldine Lofthus, Michael E Pichichero
1Department of Pediatrics, Strong Children's Research Center, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
Insights
Former extremely preterm infants showed lower antibody responses to several childhood vaccines by age 7. However, most preterm children maintained protective immunity, indicating successful immunization despite prematurity.
Area of Science:
- Immunology
- Pediatrics
- Vaccinology
Background:
- Extremely preterm infants (<29 weeks gestation) may have altered immune development.
- Routine childhood immunizations are critical for protecting infants against infectious diseases.
Purpose of the Study:
- To evaluate the immune response to routine childhood immunizations in former extremely preterm infants at 7 years of age.
- To compare antibody titers in preterm children with age-matched full-term controls.
Main Methods:
- Antibody levels to Haemophilus influenzae type b (Hib), tetanus, pertussis, diphtheria, polio, and hepatitis B were measured in 16 preterm and 16 full-term children at age 7.
- Children were followed since their primary immunizations at recommended chronological ages.
Main Results:
- Preterm children had significantly lower geometric mean titers (GMT) for diphtheria, tetanus, and Hib compared to full-term controls.
- While lower, most preterm children maintained protective antibody titers for diphtheria, tetanus, Hib, polio, and hepatitis B.
- Antibody titers for pertussis and polio serotypes 1 & 2 did not differ between groups.
Conclusions:
- Former extremely preterm infants exhibit diminished antibody responses to several vaccine antigens by age 7.
- Despite lower titers, the majority of preterm children achieve and maintain protective immunity, suggesting the effectiveness of standard immunization schedules.
Objective:
To assess the immune response of 7-year-old former extremely preterm (PT) infants to routine childhood immunizations.
Methods:
Sixteen PT (<29 weeks and <1000 g) infants, followed since their primary immunizations at the recommended chronological ages, and 16 age-matched full-term (FT) control subjects were evaluated at 7 years of age. Antibodies to Haemophilus influenzae type b polyribosylribitol phosphate (Hib-PRP), tetanus, pertussis, diphtheria, polio, and hepatitis B (HBsAb) were measured.
Results:
The FT group had higher antidiphtheria geometric mean titers (GMT) than the PT group (1.07 vs 0.36 IU/mL). All FT and 13 of 16 PT had protective diphtheria antibody titers (>0.1 IU/mL). The tetanus GMT were 4.22 IU/mL (FT) and 1.99 IU/mL (PT). All children had protective tetanus titers (>0.01 IU/mL). Pertussis titers did not differ between FT and PT. Hib-PRP GMT were higher in FT than in PT (3.21 vs 1.41 microg/mL). All children had anti-PRP > or = 0.15 microg/mL; 12 of 16 FT and 10 of 16 PT had levels > or = 1.0 microg/mL. Polio serotype 1 and 2 GMT were similar between groups, and all children had protective titers (> or = 8). Polio serotype 3 GMT were 59 (FT) and 24 (PT) Karber units; all FT and 12 of 16 PT had protective titers. Among children who had received hepatitis B vaccine, GMT were similar in FT and PT children (120 vs 186 mIU/mL, and similar proportions of children (11 of 16 FT and 12 of 14 PT) had protective HBsAb titers (>10 mIU/mL).
Conclusions:
At 7 years of age, PT children had lower antibody titers to many vaccine antigens than FT children. However, most PT children maintained antibody titers in the protective range.
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