Viral Respiratory Infections: Respiratory Syncytial Virus.

Respiratory syncytial virus (RSV) causes bronchiolitis and other significant lower respiratory infections. It spreads mainly via droplets, direct contact, and contaminated surfaces. In most of the United States, the prevalence of RSV infection peaks during the winter. Annually, RSV causes approximately 58,000 hospitalizations and more than 2 million outpatient visits among US children younger than 5 years. It also causes up to 160,000 hospitalizations and 10,000 deaths in adults 65 years and older. Prevention comprises hygiene measures, avoidance of infected individuals, and vaccine and antibody strategies. Vaccination is recommended for adults ages 50 to 74 years with chronic health conditions or weakened immune systems or who live in long-term care facilities. Vaccination is also recommended for adults 75 years and older and pregnant women (between 32 weeks' and 36 weeks and 6 days' ges-tation). The long-acting monoclonal antibody nirsevimab is recommended for infants younger than 8 months born during or entering their first RSV season and high-risk infants and young children ages 8 to 19 months. Diagnosis of RSV infection is primarily clinical, with testing used for high-risk or hospitalized patients. Treatment is support-ive. Hospitalization is needed for patients with hypoxia, dehydration, respiratory distress, or underlying high-risk conditions. Coinfections, socioeconomic disparities, and environmental factors (eg, tobacco smoke exposure) increase the risk of severe infection.