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NOTE: On July 17, 2023, the U.S. Food and Drug Administration (FDA) approved nirsevimab for the prevention of respiratory syncytial virus (RSV) lower respiratory tract disease in neonates and infants born during or entering their first RSV season and in children up to 24 months of age who remain vulnerable to severe RSV disease through their second RSV season. This article has been revised to reflect the FDA approval. For more information, see the FDA news release.

Am Fam Physician. 2023;108(1):52-57

Patient information: See related handout on respiratory syncytial virus infection.

This clinical content conforms to AAFP criteria for CME.

Author disclosure: No relevant financial relationships.

Bronchiolitis is the most common lower respiratory tract infection in young children. Respiratory syncytial virus (RSV) is the most common viral cause of bronchiolitis. RSV is spread through respiratory droplets, and the number of cases varies with season. For most patients, standard precautions (e.g., hand hygiene, surface cleaning, avoiding contact with sick individuals) are recommended. However, prophylaxis with palivizumab may be considered for infants at high risk. Initial symptoms occur after an incubation period of four to six days and include rhinorrhea, congestion, sneezing, and fever. Signs of lower respiratory tract involvement may follow and include cough, tachypnea, retractions, difficulty feeding, and accessory muscle use. Diagnosis is typically clinical; routine use of radiography or viral testing is not recommended. Treatment of RSV bronchiolitis is mainly supportive. Oxygen saturation should be maintained above 90%. Hydration and nutrition should be maintained by nasogastric or intravenous routes, if needed. Therapies such as bronchodilators, epinephrine, nebulized hypertonic saline, corticosteroids, antibiotics, and chest physiotherapy are not recommended. Although most episodes of RSV bronchiolitis are self-limited, some children have an increased risk of asthma later in life.

Bronchiolitis is the most common lower respiratory tract infection in children younger than five years. Respiratory syncytial virus (RSV) is the most common viral cause of bronchiolitis worldwide. This article summarizes the best available evidence for the management of RSV bronchiolitis.

RecommendationSponsoring organization
Do not order chest radiographs in children with uncomplicated asthma or bronchiolitis.Society of Hospital Medicine (Pediatric)
Do not use systemic corticosteroids in children younger than two years with an uncomplicated lower respiratory tract infection.Society of Hospital Medicine (Pediatric)
Do not routinely use bronchodilators in children with bronchiolitis.Society of Hospital Medicine (Pediatric)


  • RSV is spread through respiratory droplets, with symptoms developing after an incubation period of four to six days.1,2

  • The global incidence of RSV bronchiolitis is estimated to be 8.1 cases per 1,000 children per year, leading to 33 million cases and 3.6 million hospitalizations in 2019.3 In the United States, the incidence of RSV-related hospitalizations in children younger than five years is estimated at 2.9 cases per 1,000 per year.4

  • The incidence of RSV bronchiolitis varies with region and season. Before the COVID-19 pandemic, cases peaked between mid-October and May in the United States. Since COVID-19 restrictions were lifted, RSV peaks have been delayed to spring and summer.1,5,6 The Centers for Disease Control and Prevention performs surveillance for RSV and reports weekly trends by region.7

  • Age is the most important risk factor for severe disease and hospitalization. The rate of RSV- related hospitalization in infants younger than one month is estimated to be 25.1 per 1,000 (95% CI, 21.1 to 29.3). Infants born before 36 weeks of gestation are significantly more likely to need hospitalization compared with term infants.1,4

  • RSV is isolated in up to 83% of RSV cases. Viral coinfection occurs in up to 55% of cases, with human rhinovirus being the most common coisolate.8 A 2017 study over 12 epidemic seasons found that coinfection did not affect disease severity or outcomes.9


  • Standard precautions against the spread of respiratory droplets, such as hand hygiene, surface cleaning, and avoiding contact with sick individuals, are recommended.1

  • Prophylactic palivizumab, an intramuscular monoclonal antibody, may be considered for children at risk of severe infection (Table 11,2,10). Palivizumab is given monthly during RSV season, for up to five doses (15 mg per kg per dose). It should be discontinued if the child is subsequently hospitalized for RSV.1,10,11

  • A 2021 Cochrane review demonstrated that palivizumab leads to significantly fewer RSV hospitalizations (number needed to treat [NNT] = 18), but with no significant mortality benefit.11

  • One dose of nirsevimab at the start of RSV season has been shown decrease the need for outpatient evaluation (NNT = 14) and hospitalization (NNT = 30) in preterm infants (less than 35 weeks).12 In healthy late preterm infants (35 to 37 weeks) and full-term infants, one dose of nirsevimab prevents outpatient visits (NNT = 26) and may prevent hospitalization; however, further study is needed.13 Nirsevimab has been approved by the U.S. Food and Drug Administration (FDA) and is expected to be available at the start of the fall 2023 RSV season.

  • A recent phase 3 trial has shown that a single intramuscular dose of a bivalent RSV prefusion F vaccine given to pregnant patients between 24 and 36 weeks of gestation is 81.8% (99.5% CI, 40.6 to 96.3) effective in preventing medical evaluation for severe RSV in newborns through 90 days of life. The vaccine is 69.4% (97.59% CI, 44.3 to 84.1) effective through 180 days of life.14 The vaccine has been FDA-approved for high-risk children.

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