RSV Immunization

What is RSV?

Respiratory syncytial virus (RSV) is a germ that is easily spread by droplets from the nose and mouth while coughing or sneezing. It generally starts in the fall, peaks in the winter, and ends for the most part in the spring. Anyone can get RSV. An overwhelming majority of infants will develop their first RSV infection by 1 year of life and almost all by age 2.

What are the symptoms of RSV?

Most infants and children infected with RSV develop cold like symptoms including fever, nasal congestion, runny nose, and cough that typically resolve after a week or two. In some, the virus spreads into the chest affecting the small branches of the bronchial tubes (bronchiolitis), the lungs (pneumonia) or both. If mild, symptoms may include audible wheezing, worsening cough, increased respiratory rate, and mild to no respiratory distress. More severe involvement may result in an inability to safely feed, a marked increase in the rate of breathing, and moderate to severe respiratory distress. These patients may develop dehydration or low oxygen levels in their bodies requiring intravenous (IV) fluids and supplemental oxygen in the hospital. The sickest of patients may require the breathing assistance of a ventilator.

How common is severe RSV disease in infants?

In the United States, RSV leads to millions of outpatient (clinic or ER) visits and tens of thousands of hospitalizations each year. Approximately 2% of all infants require hospitalization for an RSV infection during the first year of life. Underlying health conditions, especially premature birth, chronic lung disease, and congenital heart disease, predispose children to severe RSV illness however, 80% of hospitalized infants do not have any risk factors.

What can be done to reduce the risk of a severe RSV infection?

Severe infection from RSV can be significantly reduced by providing infants with protective RSV antibodies. Antibodies are proteins that the body’s immune system uses to fight off harmful germs. Like traditional vaccines, preventive antibodies are immunizations that provide protection against a specific germ. While both are immunizations, the way they provide immunity is different. RSV antibodies can be produced in a laboratory and be given directly to a patient through an intramuscular injection. Once in the body, the antibodies provide immediate protection against RSV. Traditional vaccines are immunizations that stimulate the recipient’s immune system to produce antibodies. This process takes time and may not be complete. Currently no vaccine is available against RSV for infants. An RSV vaccine is available for pregnant women. This vaccine should be administered at 32-36 weeks of pregnancy between September and January. After a couple of weeks, the mother’s immune system makes antibodies against RSV that are passed through the placenta into the infant’s body. If given 2 weeks or more before birth, most infants will be protected against serious RSV disease and do not require additional immunization.

Is giving an infant RSV antibodies a new treatment approach?

For over 2 decades, high risk patients have been given monthly injections of RSV antibodies through the RSV season. The process was fairly involved and rather expensive. This year a new RSV antibody immunization was approved (generic name nirsevimab, trade name Beyfortus). These antibodies are more stable in the body with one injection providing protection for the entire RSV season at a significantly lesser cost. The rate of hospitalization of infants who received Beyfortus was reduced by 75%.

Who should receive preventative RSV antibodies?

The Centers for Disease Control (CDC) and the American Academy of Pediatrics (AAP) universally recommend that infants born during the RSV season should receive a single dose of the RSV immunization within 1 week after birth.

Infants born outside of the RSV season who are younger than 8 months should receive a single dose of the RSV Immunization shortly before their first RSV season (in October), but infants who are younger than 8 months who have not yet received a dose may receive a dose at any time during the season.

Some infants and young children who are at increased risk for severe RSV disease may need a single dose of the RSV antibody before or during their second RSV season as well.

Is treatment with RSV antibodies safe?

Beyfortus has been shown to be quite safe. Limited side effects include a potential rash (0.9%) and/or pain, swelling, or hardness at the injection site (0.3%). Rarely, an allergic reaction can occur.

Can RSV antibodies be given at the same time as other recommended immunizations?

RSV preventive antibodies can be given at the same time as vaccines routinely recommended for infants and young children.

SOURCE: developed with content published by the CDC at https://www.cdc.gov/vaccines/vpd/rsv/immunization-information-statement.html. Revised: 10/2024