What is RSV?

By their second birthday, nearly all children in the United States will have had respiratory syncytial virus (RSV). This highly contagious virus causes inflammation of the respiratory tract, usually resulting in cold-like symptoms.

Most kids (and adults, who can get it, too) with an RSV infection recover within a week or two, but it can be serious for those without strong immune systems, including infants and older adults, and for them it can be serious. RSV is the most common cause of bronchiolitis (inflammation of the small airways in the lungs) and pneumonia (a lung infection) in children younger than 1 in the United States.