Respiratory Syncytial Virus Has High Impact on Infants and Children

For most parents, respiratory syncytial virus (RSV) isn't a familiar term. But it's a common cause of serious respiratory infections with a major impact on the health of infants and young children worldwide, according to a special CDC review article in the June issue of the Pediatric Infectious Disease Journal.

In their article, Drs. Gayle Fischer Langley and Larry J. Anderson of the Centers for Disease Control and Prevention (CDC) present an update on the epidemiology, risk factors, and prevention of RSV infection in children. While preventive measures are available for children with certain high-risk conditions, most serious RSV infections occur in previously healthy infants and children with no underlying medical problems.

First discovered in 1956, respiratory syncytial virus is now recognized as one of the most common causes of pneumonia and other lower respiratory tract infections in infants and young children around the world. In developed countries, one to three percent of infants are hospitalized for RSV infection every year. Many more children with less severe infections are seen in emergency rooms and pediatricians' offices.

Outbreaks of RSV infection occur every year, most often between late fall and early spring. Respiratory syncytial virus can cause potentially serious infections such as pneumonia and bronchiolitisinfection of the small airways in the lungs. Infection with RSV seems to be an important risk factor for the development of wheezing or asthma later in childhood.

Children with certain medical conditions are at high risk of severe RSV disease: especially infants with chronic lung disease (CLD) of prematurity (previously called bronchopulmonary dysplasia), other premature infants, and children with congenital heart defects. Children with immune disorders or cystic fibrosis may also be at high risk. However, Drs. Langley and Anderson emphasize, "[M]ore than two-thirds of children hospitalized with RSV and 80 percent of RSV-related deaths occur among children who do not have an underlying high-risk condition."

Despite decades of effort, there is no vaccine to prevent RSV infection in healthy infants and children. Until a safe and effective RSV vaccine is developed, specific approaches to preventing RSV infection are limited.

There are some effective "immunoprophylaxis" recommended for children in high-risk groupsparticularly premature infants, with or without CLD, and children with congenital heart defects. The first effective form of immunoprophylaxis was a product called RSV immune globulin. More recently, a series of antibody products have been developed for RSV prevention in high-risk children.

Studies have shown that these preventive approaches effectively reduce the risk of severe RSV infections requiring hospitalization in the target groups of high-risk children. Immunoprophylaxis "is most cost-effective when given to infants with the greatest risk of hospitalization during the peak of the season," Drs. Langley and Anderson point out. However, because of its high cost and low likelihood of benefit in children without underlying medical conditions, immunoprophylaxis is not recommended for general use.

Thus, until an effective RSV vaccine is developed, the best way to reduce the risk of RSV infection in healthy infants and children is general infection control measures. That means good handwashing habits and avoiding places where the risk of exposure to RSV is increased, such as child care centers. Langley and Anderson also remind pediatricians and parents to be aware of the peak RSV "season" in their regionthe season starts earlier and lasts longer in the South, particularly Florida, than in other parts of the U.S.