A. Symptoms of RSV are similar to other respiratory infections. Illness begins 4 to 6 days after being exposed to the virus. In adults and older children, typical RSV symptoms include a low-grade fever, congested or runny nose, cough, sore throat, headache, fatigue, and occasionally wheezing. In children younger than age 2, RSV can cause a lower respiratory tract illness such as bronchiolitis or pneumonia; more severe cases can result in respiratory failure. For people with severe illness, symptoms may include a worsening croupy cough, unusually rapid breathing, difficulty breathing, and a bluish color of the lips or fingernails caused by low levels of oxygen in the blood. RSV can cause middle ear infections (otitis media) in preschool children.