Seven-year follow-up of vaccine response in extremely premature infants.

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.