Respiratory Syncytial Virus (RSV)

RSV stands for Respiratory Syncytial Virus. It is a common respiratory virus that infects the nose, throat, and lungs. RSV symptoms make it difficult to distinguish it from the common cold or other respiratory viruses like the flu or COVID-19.

RSV does not usually cause severe illness in healthy adults and children. However, some people with RSV infection, especially older adults and infants younger than 6 months of age, can become very sick and may need to be hospitalized.

Yes, RSV can also cause more severe illnesses such as bronchiolitis and pneumonia. It is the most common cause of bronchiolitis and pneumonia in children younger than 1 year of age.

Yes, RSV can be transmitted like other respiratory viruses. RSV can be spread by:

• A person who has RSV coughing or sneezing near you
• Getting virus droplets from a cough or sneeze in your eyes, nose, or mouth
• Having direct contact with the virus, like kissing the face of a child with RSV
• Touching a surface that has the virus on it, like a doorknob, and then touching your face before washing your hands - RSV can survive for many hours on hard surfaces

People with RSV are usually contagious for 3 to 8 days and may become contagious a day or two before they start showing signs of illness. However, some infants and people with weakened immune systems can continue to spread the virus for 4 weeks or longer, even after they stop showing symptoms.

Anyone can get RSV, but typically most people get RSV for the first time as an infant or toddler. Nearly all children will get RSV before their second birthday. However, repeat infections may occur throughout life.

However, some populations are at greater risk of severe illness from RSV, particularly infants, some young children, and older adults. RSV is the leading cause of infant hospitalization in the U.S. Children at greatest risk for severe illness from RSV include:

• Infants and young children (the younger the age, the higher the risk)
• American Indian and Alaska Native children
• Children born prematurely
• Children with chronic lung disease or congenital (present from birth) heart disease
• Children with weakened immune systems
• Children with severe cystic fibrosis
• Children who have neuromuscular disorders, especially those who have difficulty swallowing or clearing mucus secretions

RSV can also be dangerous for older adults, especially those who have certain medical conditions, are elderly or frail, or live in a nursing home. Adults at highest risk for severe RSV disease include:

• Adults ages 75 and older
• Adults with chronic heart or lung disease
• Adults with weakened immune systems
• Adults with certain other underlying medical conditions
• Adults living in nursing homes

The symptoms of RSV may vary slightly depending on age. In infants and young children, RSV may not be severe when it first starts. However, it can become more severe a few days into the illness. Early symptoms of RSV may include:

• Runny nose
• Eating or drinking less
• Cough, which may progress to wheezing or difficulty breathing

In infants less than 6 months old, symptoms may include:

• Irritability
• Decreased activity
• Eating or drinking less
• Apnea (pauses in breathing for more than 10 seconds)

Many infants will not have a fever with RSV infection.

When an adult gets RSV, they typically have mild cold-like symptoms, but some may develop pneumonia.

Yes, there are laboratory tests used to diagnose RSV. The most commonly used tests by health care providers, urgent care settings, and emergency departments are conducted by collecting a nasal sample from the patient and provide results in about an hour. 

There is no specific treatment for RSV, and most RSV infections go away on their own in a week or two. However, you can relieve the symptoms of RSV by drinking plenty of fluids to prevent dehydration and taking over-the-counter pain relievers. Never give aspirin to children and talk with your health care provider before giving a child non-prescription cold medicine.

Yes, there are RSV vaccines for older adults, pregnant women, and infants. They were first approved by the U.S. Food and Drug Administration in 2023.

The Centers for Disease Control and Prevention (CDC) recommends an RSV vaccine for all adults ages 75 years and older and for adults ages 50–74 years who are at increased risk of severe RSV. Conditions that increase risk for severe illness include:

• Chronic heart or lung disease
• Weakened immune system
• Certain other medical conditions
• Living in a nursing home

For a complete list of medical conditions that lead to increased risk of severe RSV, see Clinical Overview of RSV.

The American Academy of Pediatrics recommends all babies be protected from severe RSV by one of two immunization options: A maternal RSV vaccine given to the mother during pregnancy or an RSV antibody given to your baby. Most babies do not need both.

The maternal RSV vaccine is recommended if you are between 32 and 36 weeks pregnant during September through January in most of the U.S. Even though an individual may not be at high risk for severe RSV, this vaccine is important because it will pass the protection to the baby. From the of vaccination, it takes two weeks to develop protection (antibodies) and for protection to pass on to the baby. Protection will last during the baby’s first 6 months, while they are at highest risk of severe RSV.

If an individual has already received a maternal RSV vaccine during a previous pregnancy, CDC does not currently recommend getting another dose of RSV vaccine during subsequent pregnancies.

An RSV antibody is recommended for all babies younger than 8 months of age born to mothers who did not receive a maternal RSV vaccine during pregnancy. An antibody dose should be given to babies shortly before the RSV season (fall/winter), or within 1 week after birth if born during October to March in most of the U.S.

An antibody dose is also recommended for a small group of young children 8 through 19 months of age who are at increased risk for severe RSV. This dose should be given shortly before the child’s second RSV season. This group includes:

• Children who were born prematurely and have chronic lung disease
• Children with severe immunocompromise
• Children with severe cystic fibrosis
• American Indian and Alaska Native children

Here is a summary of the RSV information on eligibility and timing:

*Recommended timing of administration in most of the continental US. Recommended timing of administration may differ in some areas, based on state, local, or territorial guidance.

As with all vaccines, the RSV vaccines have potential side effects. Common side effects for older adults include:

• Pain where the shot is given
• Fatigue (feeling tired)
• Headache
• Muscle and joint pain
• Nausea

Common side effects for pregnant individuals include:

• Pain where the shot is given
• Headache
• Muscle pain
• Nausea

Common side effects for infants and young children include:

• Pain, redness, hardness, or swelling where shot is given
• Rash