Risk factors

By age 2, most children will have been infected with respiratory syncytial virus, but they can get infected by RSV more than once. Children who attend child care centers or who have siblings who attend school are at a higher risk of exposure and reinfection. RSV season — when outbreaks tend to occur — is the fall to the end of spring.

People at increased risk of severe or sometimes life-threatening RSV infections include:

• Infants, especially premature infants or babies who are 6 months or younger
• Children who have heart disease that's present from birth (congenital heart disease) or chronic lung disease
• Children or adults with weakened immune systems from diseases such as cancer or treatment such as chemotherapy
• Children who have neuromuscular disorders, such as muscular dystrophy
• Adults with heart disease or lung disease
• Older adults, especially those age 65 and older