RSV (Respiratory Syncytial Virus)

Updated 12/30/25 at 2:05 PM.

There are vaccines available for adults 50 and over, babies, and pregnant people to help protect against RSV. Click here to learn more.

Respiratory Syncytial Virus (RSV) is a common respiratory virus that usually causes mild, cold-like symptoms which may include:

• Runny nose
• Decrease in appetite
• Coughing
• Sneezing
• Fever
• Wheezing

*In very young infants the only symptoms may be irritability, decreased activity, and breathing difficulties.

Symptoms usually start to show within 4 to 6 days after getting infected. They often come in stages and not all at once.
 

In children it most often causes a cold-like illness but can also cause lower respiratory infections like bronchiolitis and pneumonia. Severe disease is more common in very young infants. Children with any of the following underlying conditions are considered at increased risk:

• Premature infants
• Infants, especially those 6 months and younger
• Children younger than 2 years old with chronic lung disease or congenital heart disease
• Children with suppressed or weakened immune systems
• Children who have neuromuscular disorders or a congenital anomaly, including those who have difficulty swallowing or clearing mucus secretions
• Children with severe cystic fibrosis
   

Adults usually have mild or no symptoms. If they have symptoms they are usually like that of an upper respiratory tract infection, and last less than 5 days. Adults 60 and older who are at highest risk of severe RSV disease include those with any of the following chronic conditions:

• Lung disease (such as chronic obstructive pulmonary disease [COPD] and asthma)
• Chronic cardiovascular diseases (such as congestive heart failure and coronary artery disease)
• Diabetes mellitus
• Neurologic conditions
• Kidney disorders
• Liver disorders
• Hematologic disorders
• Immune compromise
• Other underlying conditions that a healthcare provider determines might increase the risk for severe respiratory disease
   

Other underlying factors in adults that might increase the risk of severe RSV-associated respiratory illness may include the following:

• Frailty
• Advanced age
• Residence in a nursing home or other long-term care facility
• Other underlying factors that a healthcare provider determines might increase the risk for severe respiratory disease.