Description

• 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.

Epidemiology

• 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.

Incidence

• 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.

Prevalence
Difficult to conclude accurately

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).

Genetics

• 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%)