Preface

Respiratory syncytial virus (RSV) causes seasonal epidemics during the winter and wet seasons, particularly in young children. Of the children infected with RSV, 70%–90% are diagnosed with bronchiolitis and hospitalized because they need supplemental oxygen. Approximately 1% of healthy young infants are hospitalized during the first RSV season due to severe lower respiratory tract infection. Three to ten times higher rates of RSV have been reported in high-risk populations, including preterm infants; those with bronchopulmonary dysplasia; infants and children with congenital heart disease, cystic fibrosis, congenital diaphragmatic hernia, neuromuscular disease, or Down syndrome; and immunocompromised infants. After two RSV seasons and three years of age, nearly 100% of children have experienced an RSV infection or have antibodies against RSV. However, despite neutralizing antibodies, recurrent infections do occur. Severity of disease, though, decreases as children become older.

For the last 20 years, palivizumab has been used for immunoprophylaxis of RSV infections. It is a monoclonal antibody that binds to the F-glycoprotein that is 95% identical between the G- and F-receptor and thus works against RSV types A and B. Palivizumab is given to high-risk infants only, hence the burden of RSV diseases continues to grow and a vaccine is urgently needed.

Following a fatal vaccine trial in the early 1960s that led to two deaths, many efforts to develop a safe vaccine have been undertaken. This book covers the problems the young RSV patient faces and provides data on the most recent vaccine progresses and new monoclonal antibodies. It is our hope that this volume will open up new avenues to future tools in RSV prophylaxis.

Palivizumab (Synagis®, MedImmune, Inc., USA) is a humanized monoclonal antibody that provides immunoprophylaxis against respiratory syncytial virus (RSV). RSV causes seasonal epidemics (winter or wet-season) of serious lower respiratory tract infections in young infants with subsequent increased frequency of recurrent wheezing during early childhood. Two large, double-blind, placebo-controlled trials including infants at high risk for severe RSV infection showed significant reduction of RSV-related hospitalizations: a 55% reduction in 1502 infants with prematurity and/or bronchopulmonary dysplasia and a 45% reduction in 1287 infants with hemodynamically significant congenital heart disease. Palivizumab proved to be as safe as an intramuscular injection of 15 mg/kg every 30 days for

5 months according to local epidemiology. Recent data suggest further benefits for palivizumab prophylaxis by reduction of recurrent post-RSV wheezing.

> **Bernhard Resch, MD** Professor, Division of Neonatology, Department of Pediatrics and Adolescent Medicine, Medical University of Graz, Graz, Austria

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Section 1

RSV Immunology
