Key Facts
- Severe RSV can be unpredictable and is the leading cause of hospitalization in infants.
- Adults 65 and over and adults with chronic conditions or weakened immune systems are at high risk for developing severe RSV.
- People do not form long-lasting immunity to RSV and can become infected repeatedly over their lifetime.
Each year in the United States, RSV leads to:
What Causes RSV?
RSV is spread from person to person through close contact with someone who is infected via secretions from coughing and sneezing or touching objects such as toys or doorknobs that have the virus on them.
It takes between two and eight days from the time of exposure for someone to become ill. The illness normally lasts three to seven days, and it is during this time that those infected are most contagious. The peak season for RSV infection in the United States is fall through spring.
Who Is at Risk for RSV?
Most children will get an RSV before age two simply because of contact with other children. Being in crowded places with people who may be infected or having exposure to other children or siblings who may be infected are common ways to pick up the virus.
Those at increased risk of RSV becoming severe or life-threatening are:
- Infants up to one year old, especially those who are 6 months and younger
- Infants born prematurely
- Children younger than two with congenital heart disease or chronic lung disease
- Children with weakened immune systems or who have neuromuscular disorders
- Older adults
- Adults with chronic lung or heart disease, such as asthma, congestive heart failure, or chronic obstructive pulmonary disease (COPD)
- Adults with weakened immune systems, such as people receiving organ transplants, people undergoing chemotherapy or individuals with HIV/AIDS
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Understanding RSV
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Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel.
Page last updated: October 10, 2023