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.


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.
Kirmani
Khaver I
KI
Department of Pediatrics, Strong Children's Research Center, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
Lofthus
Geraldine
G
Pichichero
Michael E
ME
Voloshen
Timothy
T
D'Angio
Carl T
CT
D000914:Antibodies, Viral / Q000097:blood*; D016022:Case-Control Studies; D002648:Child; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000276:immunology; D005260:Female; D005500:Follow-Up Studies; D018073:Haemophilus Vaccines / Q000276:immunology; D017325:Hepatitis B Vaccines / Q000276:immunology; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000276:immunology*; D019102:Infant, Very Low Birth Weight / Q000276:immunology*; D008297:Male; D011055:Poliovirus Vaccine, Oral / Q000276:immunology; D014612:Vaccines / Q000276:immunology*
D000914:Antibodies, Viral; D015721:Diphtheria-Tetanus-Pertussis Vaccine; D018073:Haemophilus Vaccines; D017325:Hepatitis B Vaccines; D011055:Poliovirus Vaccine, Oral; D014612:Vaccines