In infants and young children, almost all primary infections are symptomatic, and 40 percent or more are associated with bronchiolitis or pneumonia. Febrile upper respiratory tract illness and otitis media are common. Approximately one to two percent of infections result in hospitalization, and about 10 percent of hospitalized infants require ventilatory support. Mortality is usually less than one percent among previously healthy infants but is much higher in those with primary immunodeficiency, those undergoing cancer chemotherapy, or those with preexisting pulmonary and heart disease. Most recurrent infections in adults are associated with upper respiratory tract illness.
Adults typically experience coryza, pharyngitis, and cough, often with lowgrade fever.
Bronchitis, influenzal illness, pneumonia, and exacerbations of asthma and chronic bronchitis also occur. Influenza and RSV infections are associated with similar clinical pictures and outcomes in the elderly. Elderly adults hospitalized with RSV commonly manifest dyspnea, wheezing, and sputum production. Viral bronchopneumonia or secondary bacterial pneumonia appears to complicate a high proportion of RSV infections in such patients. RSV causes severe lower respiratory tract disease in immunosuppressed patients, particularly bone marrow transplant recipients.