Background: The heptavalent pneumococcal CRM197 conjugate vaccine (PCV-7) has been incompletely studied in very-low-birth-weight (≤1500 g) infants.
Objective: To assess PCV-7 immunogenicity in very-low-birth-weight, premature infants. We hypothesized that the frequency of postvaccine antibody concentrations ≥0.15 μg/mL would vary directly with birth weight.
Methods: This was a multicenter observational study. Infants 401 to 1500 g birth weight and <32 0/7 weeks gestation, stratified by birth weight, were enrolled from 9 National Institute of Child Health and Human Development Neonatal Research Network centers. Infants received PCV-7 at 2, 4, and 6 months after birth and had blood drawn 4 to 6 weeks following the third dose. Antibodies against the 7 vaccine serotypes were measured by enzyme-linked immunosorbent assay.
Results: Of 369 enrolled infants, 244 completed their primary vaccine series by 8 months and had serum obtained. Subjects were 27.8 ± 2.2 (mean ± standard deviation) weeks gestation and 1008 ± 282 g birth weight. Twenty-six percent had bronchopulmonary dysplasia and 16% had received postnatal glucocorticoids. Infants 1001 to 1500 g birth weight were more likely than those 401 to 1000 g to achieve antibody concentrations ≥0.15 μg/mL against the least 2 immunogenic serotypes (6B: 96% vs. 85%, P = 0.003 and 23F: 97% vs. 88%, P = 0.009). In multiple logistic regression analysis, lower birth weight, postnatal glucocorticoid use, lower weight at blood draw, and Caucasian race were each independently associated with antibody concentrations <0.35 μg/mL against serotypes 6B and/or 23F.
Conclusions: When compared with larger premature infants, infants weighing ≤1000 g at birth have similar antibody responses to most, but not all, PCV-7 vaccine serotypes.
From the *University of Rochester School of Medicine and Dentistry, Rochester, NY; †Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX; ‡Department of Pediatrics, Wake Forest University School of Medicine, Winston-Salem, NC; Departments of §Pediatrics, and ¶Pathology, University of Alabama at Birmingham, Birmingham, AL; ∥Department of Pediatrics, Wayne State University, Detroit, MI; **Department of Pediatrics, University of Miami, Miami, FL; ††Department of Pediatrics, Duke University, Durham, NC; ‡‡Department of Pediatrics, Emory University, Atlanta, GA; §§Department of Pediatrics, Stanford University School of Medicine, Palo Alto, CA; ¶¶Department of Pediatrics, Women and Infants Hospital, Brown University, Providence, RI; ∥∥Statistics and Epidemiology Unit, RTI International, Research Triangle Park, NC; and ***Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD.
Accepted for publication January 4, 2010.
This study was registered at www.clinicaltrials.gov (NCT00273325).
The Neonatal Research Network's PCV-7 Study was supported by grants from the National Institutes of Health and from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). The funding agency provided overall oversight for study conduct. PCV-7 vaccine was purchased directly by infants' clinical care providers.
All authors confirm that they made substantial contributions to the work, were involved in the drafting and/or reviewing of the article, and have approved the version to be published. No author has a relevant financial interest or other conflict of interest as regards this research.
Address for correspondence: Carl T. D'Angio, MD, Box 651, Neonatology, Golisano Children's Hospital, University of Rochester Medical Center, 601 Elmwood Ave, Rochester, NY 14642. E-mail: email@example.com.
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