Respiratory Syncytial Virus Activity - United States, July 2008-December 2009

Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis and pneumonia in the children aged less than one year worldwide. Among adults aged greater than 65 years, an estimated 177,000 hospitalization and 14,000 deaths a year have been attributed to RSV infections. In temperate climates, the RSV season generally begins during the fall and continues through the winter and spring, but the exact timing of RSV circulation varies by location and year. Using data from the National Respiratory and Enteric Virus Surveillance System, Villarruel et al provide a summary of 2008-2009 RSV season and 2009-2010 season onset. A CDC editorial note is presented.