Respiratory syncytial virus infection (RSV)

RSV belongs to the genus *Orthopneumovirus* and is a single-stranded, negative-sense RNA virus. It is host-specific, with human RSV being the primary pathogen of clinical significance in humans. The virus targets epithelial cells of the respiratory tract, initiating infection in the upper airways before potentially descending to involve the lower respiratory tract. Human RSV is the most common viral cause of acute lower respiratory infection in infants and young children globally.

Infection typically presents with mild upper respiratory symptoms—such as rhinorrhea, cough, and low-grade fever—in older children and adults. In infants and young children, however, it may progress to more severe manifestations including wheezing, tachypnea, hypoxia, and bronchiolitis or pneumonia. Severe disease is associated with hospitalization, particularly among infants under six months of age, those with underlying cardiopulmonary conditions, or immunocompromised individuals. Long-term sequelae such as recurrent wheezing have been reported following severe infantile RSV infection, though source-supported details on long-term outcomes are not provided here.

RSV circulates globally and is endemic year-round in temperate climates, with seasonal peaks typically occurring in late fall through early spring. In tropical regions, transmission may be more continuous or exhibit less pronounced seasonality. The virus is highly transmissible and infects nearly all children by age two. While the burden is highest in infants and young children, older adults and immunocompromised individuals also experience significant morbidity and mortality. Surveillance data from Japan’s weekly sentinel system suggest consistent detection across seasons, indicating sustained community circulation.

RSV spreads primarily via direct contact with respiratory secretions or contaminated surfaces, followed by self-inoculation through the mucosa. Aerosolized droplets generated during coughing or sneezing are also an important route of transmission. The virus can persist on non-living surfaces for several hours, facilitating indirect transmission. Close household contact and crowded settings increase exposure risk, especially among young children.

Infants and young children, especially those under six months of age, are at highest risk for severe disease. Additional vulnerability is conferred by prematurity, chronic lung disease, congenital heart disease, and immunodeficiency. Older adults, particularly those with comorbidities or living in institutional settings, also face elevated risk of hospitalization and complications. No other specific demographic or occupational groups are identified in the source material.

No licensed vaccine is currently available; prevention relies on non-pharmaceutical interventions such as hand hygiene, environmental disinfection, and avoidance of close contact with symptomatic individuals. Palivizumab, a monoclonal antibody, is indicated for prophylaxis in select high-risk infants (e.g., those born prematurely or with congenital heart disease), though its use is not described in the provided sources. Supportive care remains the cornerstone of management for infected individuals.

RSV should be monitored through syndromic surveillance of acute respiratory illness, particularly in pediatric populations and among hospitalized patients with lower respiratory symptoms. Weekly sentinel surveillance in Japan provides timely indicators of circulating virus activity and seasonal trends. Detection of RSV in outpatient or inpatient settings warrants consideration of patient risk factors and potential need for supportive interventions. Source-backed detail on case definitions, testing protocols, or regional variation in burden is not available in the provided snippets.

1. 1 Wikidata. Respiratory Syncytial Virus Infection (RSV).
2. 2 Wikipedia. Orthopneumovirus.

ICD-10

ICD-11

Total cases

2.3M

Peak month

2021-07

Coverage

2 reporting countries · 2000-01-01 → 2026-05-02