Respiratory Syncytial Virus

Abstract

What is RSV and Who is at Risk? • RSV is the most common cause of bronchiolitis (infl ammation of the small airways in the lung) and pneumonia in children under 1 year of age in the United States. • Almost all children are infected with the virus by their second birthday, but only a small percentage develops severe disease. • Premature infants, children less than 2 years of age with congenital heart disease or chronic lung disease, and children with compromised (weakened) immune systems due to a medical condition or medical treatment are at highest risk for severe disease. Adults with compromised immune systems and those aged 65 years and older are also at increased risk of severe disease. • RSV infections generally occur in the United States from November to April. However, the timing of the season may diff er among locations and from year to year.