Respiratory Syncytial Virus (RSV) is a virus that infects the lungs and airways. RSV can affect anyone of any age, but it is most common in infancy and early childhood. Almost all children will have been infected with RSV by the time they are two to three years old.
RSV infections tend to occur during colder weather. The peak RSV season usually lasts from November to April in Canada, but the season may vary.
RSV is usually a mild disease that goes away on its own. In premature babies and in children less than two years old with certain lung conditions or congenital heart disease, RSV can lead to serious lung infections. When this happens, babies can become very sick and may require hospitalization.