DESCRIPTION

• RSV remains one of the most common causes of childhood illness and the most common cause of hospitalization in infants, with 90–95% of children infected by 24 months of age. It imposes a considerable threat to child health with acute and long-term morbidity and mortality, including viral lower respiratory tract infection (LRTI), respiratory failure, and death. In adults, RSV typically causes upper respiratory tract infection (URTI), but life-threatening LRTI/acute cardiac events and worsening of asthma/COPD/CHF can occur in high-risk populations.
• Seasonality: begins in the fall, peaks in the winter, and ends in the spring

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 neutrophil-intensive airway inflammation. It develops in the cytoplasm of infected cells and matures by budding from the plasma membrane.

RISK FACTORS

• Significant association with RSV-associated acute LRTI
  • Infants born prematurely; low birth weight, male gender; underlying cardiopulmonary disease; HIV; Down syndrome
  • Any age group with persistent asthma; children aged <5 years with socioeconomic vulnerability; immunodeficiency; siblings with asymptomatic RSV infection; second-hand smoke; history of atopy, no breastfeeding; adult patients with COPD or functional disability
  • Other risk factors: daycare center attendance; exposure to indoor and environmenstal air pollutants; multiple births, malnutrition, higher altitude
• For severe or life-threatening RSV infection
  • Preterm infants born ≤28 weeks of age, 6 days of gestation, or who are <12 months of age at the start of RSV season; infants with bronchopulmonary dysplasia who are <1 year of age or <23 months of age and requiring treatment; infants ≤12 months of age who are being medically treated for acyanotic heart disease or have moderate to severe pulmonary hypertension
• Children aged <2 years with congenital heart disease, chronic lung disease, weakened immune systems, or who have neuromuscular disorders.
• Adults ≥75 years of age living in nursing homes or long-term care facilities or adults with chronic lung or heart disease, such as asthma, congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), severe diabetes, severe obesity, weakened immune systems (HIV/AIDS, organ transplant recipients, receiving chemotherapy)

GENERAL PREVENTION

• Practice good hygiene by covering coughs and sneezes, washing or sanitizing hands often, and cleaning frequently touched surfaces (1)[B]. Avoid passive smoke exposure (1)[B]. Isolate patients with proven or suspected RSV.
• Immunizations:
  • Adult: single-dose RSV vaccine for everyone ≥75 years of age and adults ages 60 to 74 years of age at increased risk of severe RSV disease; adults who have received the RSV vaccine should not receive another dose.
  • Pregnancy: A single dose of bivalent PreF vaccine at 32 to 36 weeks pregnant with seasonal administration during September to January in the United States will protect against severe RSV illness in an infant for up to 6 months of age.
  • Infants: anti-RSV monoclonal antibody (mAb) for infants aged <8 months old entering their 1st RSV season if the mother is unimmunized or inadequate immune response, or for children between the ages of 8 and 19 months who are at increased risk of severe RSV disease before their 2nd RSV season. The following are the available anti-RSV mAb:
    • Palivizumab is a first-generation, short-acting mAb that requires monthly intramuscular injection during RSV season.
    • Nirsevimab is a long-acting, high-potency, new-generation mAb that provides protection for five months with a single intramuscular injection before the RSV season.
    • Clesrovimab is also a new-generation mAb undergoing clinical trials. It has demonstrated excellent serum concentrations and preliminary efficacy.
• Probiotics protect against RSV infection in neonatal mice through a microbiota-AM axis, suggesting that the probiotics may be a promising candidate to prevent and treat RSV infection, and deserve more research and development in future.
• Breastfeeding can significantly reduce hospitalizations due to respiratory infections.

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); apnea (8.8%); bacterial pneumonia (7.6%)