Most children are infected at least once by age 2 and continue to be reinfected throughout life. In temperate climates, RSV infections usually occur in the winter. Peaks occur in January and February in the United States. The virus is found in discharges from the nose and throat of an infected person. RSV infections can range from very mild illness to serious lower respiratory tract infections, including pneumonia, that occur mostly in the very young, the very old, and those with weakened immune systems.
Symptoms can last for a few days to several weeks.
Signs and symptoms in young children are usually mild and similar to a cold. They include stuffy nose, cough, and sometimes ear infection. In older children and adults, RSV causes upper respiratory infection involving the nose, throat, or sinuses. Children who develop a lower respiratory tract infection often have low-grade fever for several days, a cough that sometimes lasts more than 2 weeks, and respiratory symptoms including difficult or rapid breathing and deep coughing. Symptoms in newborns and young infants may include irritability, listlessness, and poor feeding.