Respiratory Syncytial Virus (RSV) Infection


Respiratory syncytial virus (RSV) is a medium-sized, membrane-bound RNA virus that causes acute respiratory tract illness in patients of all ages.


  • In adults, RSV causes upper respiratory tract infection (URTI).
  • In infants and children, RSV commonly presents as lower respiratory tract infection (LRTI) that manifests as bronchiolitis and rarely pneumonia, respiratory failure, and death.

Pediatric Considerations

  • 90–95% of children are infected by 24 months.
  • Leading cause of pediatric bronchiolitis (50–90%)
  • Premature infants and infants under the age of 6 months are at increased risk.


  • Seasonality:
    • Outbreaks of RSV disease occur each winter (October to late January).
  • Morbidity and mortality:
    • RSV infection leads to >100,000 annual hospitalizations.
    • In the United States, 2.1 million outpatient visits for RSV in children <5 years.


  • Worldwide, RSV is responsible for approximately 33 million LRTI/year and up to 199,000 childhood deaths.
  • RSV is the most common etiology of pneumonia in children (29%).
  • 177,000 hospitalizations, 14,000 annual deaths are attributable to RSV in the elderly.
  • The COVID-19 pandemic significantly impacted RSV presentations to clinical care.

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Etiology and Pathophysiology

  • RSV is a single-stranded, negative-sense RNA virus belonging to the Paramyxoviridae family.
  • Two subtypes, A and B, are simultaneously present in most outbreaks with A subtypes causing more severe disease.
  • RSV is spread via direct contact or droplet aerosols. Incubation period ranges from 2 to 8 days, mean 4 to 6.
  • Natural RSV infections result in incomplete immunity; recurrent infections are common.
    • RSV causes a neutrophil-intensive inflammation of the airway.
    • RSV develops in the cytoplasm of infected cells and matures by budding from the plasma membrane.
    • RSV is a major cause of exacerbation of asthma and chronic obstructive pulmonary disease (COPD).


  • Severe RSV infections may be associated with polymorphisms in cytokine-related genes, including CCR5; IL4; IL8, IL10, and IL13.
  • RSV replicates in apical ciliated bronchial epithelial cells. The airway epithelium produces chemokines, which recruit neutrophils.

Risk Factors

  • Significant association with RSV-associated acute LRTI
    • Infants born before the 35 weeks’ gestation
    • Low birth weight, male gender
    • Underlying cardiopulmonary disease
    • HIV
    • Down syndrome
    • Any age group with persistent asthma
    • Children <5 years with socioeconomic vulnerability
    • Immunodeficiency
    • Siblings with asymptomatic RSV infection
    • Secondhand smoke
    • History of atopy, no breastfeeding
    • Adult patients with COPD or functional disability
    • Other risk factors
      • Daycare center attendance
      • Exposure to indoor and environmental air pollutants
      • Multiple births, malnutrition, higher altitude

General Prevention

  • Hand hygiene is the most important step to prevent the spread of RSV (1)[B].
    • Use alcohol-based rubs for hand decontamination when caring for children with bronchiolitis. When alcohol-based rubs are not available, wash hands with soap and water (1)[B].
  • Avoid passive smoke exposure (1)[B].
  • Isolate patients with proven or suspected RSV.
  • Palivizumab is a humanized monoclonal antibody for the prevention of severe RSV in high-risk children (2)[A]:
    • Preterm infants born ≤28 weeks, 6 days of gestation, or who are <12 months at start of RSV season
    • Infants with bronchopulmonary dysplasia who are <1 year or <23 months and requiring treatment
    • Infants ≤12 months of age who are being medically treated for acyanotic heart disease or have moderate to severe pulmonary hypertension
  • Prophylactic use is indicated for infants and children <24 months of age with:
    • Chronic lung disease (CLD) of prematurity
    • Hemodynamically significant congenital heart disease
      • Congenital abnormalities of the airway or neuromuscular disease
  • AAP guidelines (2)[A]:
    • Preterm infants born <29 weeks’ gestational age (wGA) and <1 year at the RSV season start date
    • Infants in the 1st year of life with CLD of prematurity
    • Infants with HS-CHD <1 year at the season start date
  • Dosage: maximum of 5 monthly doses beginning in November or December at 15 mg/kg per dose IM
  • Breastfeeding can significantly reduce hospitalizations due to respiratory infections (3)[A].

Commonly Associated Conditions

In hospitalized infants:

  • Pulmonary infiltrates/atelectasis (42.8%)
  • Otitis media (25.3%)
  • Hyperinflation (20.8%); respiratory failure (14%)
  • Hyperkalemia (10.1%, defined as K+ >6.0)
  • Apnea (8.8%); bacterial pneumonia (7.6%)

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