Respiratory Syncytial Virus (RSV) Infection

Respiratory Syncytial Virus (RSV) Infection is a topic covered in the 5-Minute Clinical Consult.

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Respiratory syncytial virus (RSV) is a medium-sized, membrane-bound RNA virus that causes acute respiratory tract illness in patients of all ages. The most clinically significant disease occurs in infants and children <3 years old.


A major cause of upper respiratory tract infection (URTI) or lower respiratory tract infection (LRTI/bronchiolitis) illness

  • In adults, RSV causes URTI.
  • In infants and children, RSV causes URTI and LRTI (bronchiolitis and pneumonia-LRTI).
Pediatric Considerations
  • 90–95% of children are infected by the age of 24 months; reinfection is common.
  • Leading cause of pediatric bronchiolitis (50–90%)
  • Premature infants are at increased risk for severe acute RSV infection.


  • Seasonality: Highest incidence of RSV in the United States occurs between December and March.
  • Morbidity: RSV infection leads to >100,000 annual hospitalizations. In the United States, there are an estimated 2.1 million outpatient visits for RSV in children <5 years; the most hospitalizations are in the first 3 months of life.
  • Mortality: Deaths associated with RSV are uncommon. Children with complex chronic conditions account for the majority of deaths, and the relative contribution of RSV infection to their deaths is unclear (1).

Etiology and Pathophysiology

  • RSV-induced bronchiolitis causes acute inflammation, edema, and necrosis of small airway epithelium, air trapping, bronchospasm, and increased mucus production.
  • RSV develops in the cytoplasm of infected cells and matures by budding from the plasma membrane.
  • Infection spreads through droplets, (airborne or personal contact) that inoculate the nasal epithelium.

  • A genetic predisposition to severe RSV infections may be associated with polymorphisms in cytokine- and chemokine-related genes, including CCR5; IL4; IL8, IL10, and IL13.
  • Infants with transplacentally acquired antibody against RSV are not fully protected against infection but may have milder symptoms.

Risk Factors

  • Risk factors for severe disease
    • Prematurity
    • Age <12 weeks
    • Underlying cardiopulmonary disease
    • Immunodeficiency
  • Other risk factors
    • Low socioeconomic status
    • Exposure to environmental air pollutants
    • Child care attendance
    • Severe neuromuscular disease
    • Adults: occupational exposure to young children, hospital staff, teachers, and daycare workers

General Prevention

  • Hand hygiene is the most important step to prevent the spread of RSV.
    • Alcohol-based rubs are preferred. Hand washing with soap and water is acceptable but less effective (2)[B].
  • Avoid passive smoke exposure, especially infants and children (3)[A].
  • Isolate patients with proven or suspected RSV.
  • Palivizumab (Synagis) is a monoclonal antibody directed against the fusion (F) protein of RSV.
    • Prophylactic use is indicated for infants and children <24 months of age with:
      • Chronic lung disease of prematurity requiring medical therapy within 6 months of the start of RSV season
      • Hemodynamically significant congenital heart disease
      • Congenital abnormalities of the airway or neuromuscular disease that compromises handling airway secretions
    • Infants born at ≤29 weeks’ gestation if they are <12 months of age at the start of the RSV season; maintain prophylaxis through end of RSV season.
    • Infants born at 29 to 32 weeks’ gestation if they are <6 months of age at the start of the RSV season; prophylaxis should be maintained through the end of the RSV season.
    • Infants born at 32 to 35 weeks’ gestation who are <3 months of age at the start of the RSV season or who are born during the RSV season if they have one of the following two risk factors:
      • Infant attends child care.
      • ≥1 more siblings or other children <5 years of age living permanently in the child’s household
  • Dosage: maximum of 5 monthly doses beginning in November or December at 15 mg/kg per dose IM

Commonly Associated Conditions

  • Asthma
  • Otitis media
  • Serious bacterial infection (SBI) in infants and children with concurrent RSV infection is rare.

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