Evaluation of recent New Vaccine Surveillance Network data regarding respiratory syncytial virus hospitalization rates in US preterm infants

Figures & data

Table 1. Palivizumab use in preterm infants by gestational age, 2000–2007.

Gestational Age, wk	Average Annual Number of Preterm Infants in U.S.*	Palivizumab Use in NVSN (2000–2007)	Palivizumab Use in Florida Medicaid (2004–2005)^12
<32	49,510	59%^†	68%
32–35	301,302	N/A^‡	23%
Overall <37	350,812	27%^§	N/A

AAP, American Academy of Pediatrics; CDC, Centers for Disease Control and Prevention; N/A, not available; NVSN, New Vaccine Surveillance Network; wGA, weeks’ gestational age.

*Average number of preterm infants surviving the neonatal period derived from the 2000–2005 CDC Natality File data.¹⁴

^†Estimate derived from 2001–2007 NVSN data for preterm infants <32 wGA, excluding those infants with chronic lung disease. An estimate of utilization in infants <32 wGA including those with chronic lung disease was not provided. Inclusion of infants with chronic lung disease would have resulted in a higher proportion as utilization in infants with chronic lung disease was 90%.¹¹

^‡The study did not identify any 32–35 wGA infants who were eligible by AAP guidelines in their analysis, as they were only able to determine the presence of exposure to tobacco smoke and daycare attendance from the medical record and could not determine the presence of other relevant risk factors such as school-age siblings. The overall proportion of all 32–35 wGA infants receiving palivizumab was not reported. However, palivizumab use in infants 32–35 wGA overall appeared low, as only 7 infants 32–35 wGA and <6 months at RSV season start received palivizumab, compared with a calculated 22 palivizumab recipients <32 wGA and <6 months at RSV season start.¹¹

^§Estimate derived from 2000–2005 NVSN data for preterm infants with RSV-negative hospitalizations.¹

Table 2. In-hospital palivizumab use in preterm infants by gestational age, 2006–2007.

Gestational Age, wk	Average Annual Number of Preterm Infants in U.S.*	National Survey of In-Hospital Palivizumab Use (2006–2007)^†
<31	38,024	83%
31–34	96,856	36%
35–36	215,932	4%
Overall <37	350,812	21%

*Average number of preterm infants surviving the neonatal period derived from the 2000–2005 Centers for Disease Control and Prevention Natality File data.¹⁴

^†Estimates derived from 2006–2007 national survey of in-hospital palivizumab administration.¹³

Figure 1. RSV-related hospitalization rate per 1000 children in infants >34 wGA compared with infants A) <29 wGA, B) 29–31 wGA, and C) 32–34 wGA. The number of RSV hospitalizations identified for each time period is displayed below each figure; the NVSN authors did not report the denominator or the 95% confidence intervals of the rates. RSV, respiratory syncytial virus; wGA, weeks' gestational age.