VLBW infants participating in a PCV-7 immunogenicity study1
were enrolled from 4 NICHD Neonatal Research Network (NRN) sites (Detroit, MI, Rochester, NY, Dallas, TX and Birmingham, AL). The study was approved by NRN and each site's institutional review board. Written informed consent was obtained from each subject's parent/guardian. Infants received PCV-7 at approximately 2, 4 and 6 months of age.
NP cultures were obtained at the PRE and POST visits. Antimicrobial susceptibility testing of all pneumococcal isolates was performed.
Pneumococcal isolates were serotyped at the Centers for Disease Control and Prevention, Atlanta, GA. Serotypes 4, 6B, 9V, 14,18C, 19F, and 23F were classified as vaccine serotypes (VT). Other serotypes were classified as non-VT (NVT).
against seven VT were measured at POST visit and ≥0.15μg/ml was chosen as a possible measure of protective level.3
Descriptive statistics were used to characterize the study subjects with regard to birth weight, gestational age at birth (GA) and chronologic age (CA) at swab collection, as well as serotype and antimicrobial susceptibilities of pneumococcal isolates.