11 / 48 rsv and babies respiratory syncytial virus (rsv) is a common virus that affects the lungs and breathing passages. babies often get it before the age of two, during the rsv season from november to april. signs and symptoms of rsv include: cough, fever, irritability, runny nose, sneezing, sluggishness or being inactive, trouble breathing, and wheezing. according to the march of dimes, parents should contact their