Severe respiratory syncytial virus bronchiolitis: epidemiologic variations associated with the initiation of palivizumab in severely premature infants with bronchopulmonary dysplasia.

BACKGROUND: The efficacy of palivizumab prophylaxis after bronchopulmonary dysplasia (BPD) has been demonstrated in a single placebo-controlled trial. Concern has emerged about the degree of efficacy of palivizumab. This study was designed to determine the efficacy of administration of palivizumab to premature infants with a gestational age </=32 weeks, a past history of BPD and younger than 6 months of age at the start of the epidemic. METHODS: Prospective observational study of respiratory syncytial virus (RSV) bronchiolitis requiring hospitalization in Burgundy (12 hospitals) from December 1 to April 30 of the next year during 3 successive epidemic seasons (1999-2000, 2000-2001 and 2001-2002). The regional perinatal database provided perinatal epidemiologic characteristics of the population as a whole and of cohorts of children at risk for severe RSV infection born between April 15 and January 31 of the following year. Palivizumab was used in the 2000-2001 and 2001-2002 periods only. RESULTS: The 3 epidemics included respectively 377, 310 and 328 children born during April 15 to January 31 of the following year. The 3 epidemics differed significantly by the proportion of severely premature infants with BPD (3.2% versus 0.7 and 0.3%). In the cohort of severely premature infants with BPD born in 1999-2000, 2000-2001 and 2001-2002, the hospitalization rate for RSV bronchiolitis decreased significantly from 12 of 26 to 2 of 17 and 1 of 26 (46.2% versus 11.8 and 3.8%; P < 0.01). Sixteen of 17 and 23 of 26 premature infants with a gestational age </=32 weeks and with BPD had been treated with palivizumab in the years 2000-2001 and 2001-2002. CONCLUSIONS: This study strongly supports the efficacy of prevention of RSV bronchiolitis by palivizumab in severely premature infants with BPD.