What is respiratory syncytial virus (RSV)?

Respiratory syncytial virus (RSV) is the major cause of infections of the breathing passages and lungs in infants and young children. In addition to causing pneumonia, it is the leading cause of bronchiolitis (an infection of the bronchioles, the small breathing tubes of the lungs).

RSV is transmitted from an infected child by secretions from the nose or mouth by direct contact or by droplets in the air. The period of greatest contagiousness is in the first two to four days of the infection. RSV can last between two and eight days, but symptoms can remain for up to three weeks. RSV occurs more commonly during the winter and early spring.

RSV infects almost all children at least once before they are two years old. Most of the time, this virus only causes minor cold-like symptoms. However, for some babies, infection can be more dangerous.

For certain infants who are premature or who are born with heart disease or lung disease, RSV infection can be especially serious. Preterm infants often have underdeveloped lungs and may have difficulty fighting an RSV infection once they become infected.

What are the signs and symptoms of RSV?

Signs and symptoms of RSV include, but are not limited to:

  • Fever (temperature above 100 degrees Fahrenheit)
  • Cough
  • Wheezing
  • Runny nose
  • Rapid breathing
  • Deep breathing
  • Blue colored lips or fingernails
  • Poor appetite

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy