Learn About Respiratory Syncytial Virus (RSV)

Key Facts

  • RSV is a common virus that causes cold-like symptoms in children and adults.
  • The peak season for RSV infection in the United States is fall through spring.
  • Infants are a high-risk group, with about 5% to 20% requiring hospitalization, and 25% to 40% developing complications like bronchiolitis or pneumonia.
  • The elderly 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.

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.

Who Is at Risk for RSV?

Most children contract 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.

People who are at increased risk of RSV becoming severe or life-threatening are:

  • Premature infants
  • Young children born with congenital heart or lung disease
  • Children with weakened immune systems
  • Older adults suffering from lung or heart disease, such as asthma, congestive heart failure, or chronic obstructive pulmonary disease (COPD)
  • People with immunodeficiency, such as organ transplant recipients, chemotherapy patients or  HIV/AIDS patients

Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel.

Page last updated: January 4, 2022

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