PEDIATRICS Vol. 123 No. 3 March 2009, pp. 951-958 (doi:10.1542/peds.2008-0231)
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ARTICLE |
Evaluation of Vaccine Coverage for Low Birth Weight Infants During the First Year of Life in a Large Managed Care Population
a UCLA Center for Vaccine Research, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California
b Department of Pediatrics, Kaiser Foundation Hospital, Panorama City, California
OBJECTIVE. There are few recent population-based assessments of vaccine coverage in premature infants available. This study assesses and compares age- and dose-specific immunization coverage in children of different birth weight categories during the first year of life.
METHODS. We performed a retrospective cohort analysis of computerized vaccination data from a large managed care organization in southern California. The participants were children born between January 1, 1997, and December 31, 2002, and continuously enrolled from birth to at least 12 months of age in the Southern California Kaiser Permanente health plan. We measured age-specific up-to-date and age-appropriate immunization rates according to birth weight (extremely low birth weight: <1000 g; very low birth weight: 1000–1499 g; low birth weight: 1500–2499 g; normal birth weight: 
2500 g) for 4 vaccines (hepatitis B, diphtheria and tetanus toxoids with pertussis, Haemophilus influenzae type b, and poliovirus) through the first year of life.
RESULTS. We identified 127 833 infants born during the study period and continuously enrolled through the first year of life; 120 048 were normal birth weight infants; 6491 were low birth weight infants; 788 were very low birth weight infants; and 506 were extremely low birth weight infants. Vaccine-specific age-appropriate immunization rates were 3% to 15% lower for low birth weight infants and 17% to 33% lower for extremely low birth weight infants compared with the rates for normal birth weight infants in the first 6 months of life. Extremely low birth weight infants had the lowest age-specific up-to-date immunization levels (5%–31% lower) compared with normal birth weight infants at each age assessed. By 12 months, extremely low birth weight infants still had significantly lower up-to-date levels (87%) compared with very low birth weight, low birth weight, and normal birth weight infants (91%–92%).
CONCLUSIONS. Despite recommendations that lower birth weight infants be vaccinated as the same chronological age as normal birth weight infants, extremely low birth weight and very low birth weight infants are immunized at significantly lower rates relative to low birth weight and normal birth weight infants at 2, 4, and 6 months of age. However, by 12 months of age this finding persists only in extremely low birth weight infants.
Key Words: low birth weight • preterm • vaccine coverage
Abbreviations: LBW—low birth weight • AAP—American Academy of Pediatrics • Hib—Haemophilus influenzae type b • NBW—normal birth weight • ELBW—extremely low birth weight • VLBW—very low birth weight • SCKP—Southern California Kaiser Permanente • DTP—diphtheria, tetanus, and whole-cell pertussis • DTaP— diphtheria, tetanus, and acellular pertussis • VSD—Vaccine Safety Datalink • MCO—managed care organization • ACIP—Advisory Committee on Immunization Practices • AAI—age-appropriate immunization • UTD—up-to-date
Accepted Jul 11, 2008.
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