Survey of pediatric ward hospitalization due to respiratory syncytial virus infection after the introduction of palivizumab to high-risk infants in Japan

Background: Respiratory syncytial virus (RSV) infection is a major cause of hospitalization during the winter among infants and young children. In 2002 palivizumab was introduced to high-risk infants for RSV hospitalization in Japan. It is important to characterize the hospitalized children due to RSV infection after the introduction of palivizumab. Methods: A survey was conducted to collect the data from the hospitalized children at 12 participating hospitals during the winter of 2007. Results: From October 2007 through April 2008, 8163 children were admitted to participating hospitals, with RSV infection accounting for 811 of those hospitalizations. Mean age in children with RSV infection at hospitalization was 12.4 +/- 12.7 months, and children under 24 months of age accounted for 86.4%. The mean gestational age of those at birth was 38.0 +/- 2.6 weeks, with 82.4% of the children born at term. Palivizumab was administered in 24 cases of RSV infection, while there were 28 patients who were not treated with palivizumab, even though they met the indication for palivizumab. Death, in a total of five cases, occurred in children who were not treated with palivizumab. Conclusions: Palivizumab has been widely used in high-risk infants who were covered by health insurance, and most of the hospitalized children with RSV infection in the study hospitals were not treated with palivizumab.