Respiratory syncytial virus (RSV)
RSV is an RNA virus, classified as a pneumovirus. Subgroups A and B have been identified.
RSV is the most common cause of lower respiratory tract illness in young infants and is responsible for > 50,000 hospitalizations annually in the United States in children under the age of 5 years.
RSV is ubiquitous; almost all children are infected by age 4 years. Outbreaks typically occur annually in winter or early spring in temperate climates. However, RSV and other respiratory virus circulation patterns were disrupted during the COVID-19 pandemic (1 Reference Respiratory syncytial virus and human metapneumovirus infections cause seasonal lower respiratory tract disease, particularly in infants and young children. Disease may be asymptomatic, mild... read more ).
Because the immune response to RSV does not protect against reinfection, the attack rate is approximately 40% for all exposed people. However, antibody to RSV decreases illness severity.
Human metapneumovirus (hMPV)
hMPV is a similar but separate virus.
The seasonal epidemiology of hMPV appears to be similar to that of RSV, but the incidence of infection and illness appears to be substantially lower.
Reference
1. Olsen SJ, Winn AK, Budd AP, et al: Changes in influenza and other respiratory virus activity during the COVID-19 pandemic–United States, 2020-2021. MMWR Morb Mortal Wkly Rep 70(29):1013–1019, 2021. doi: 10.15585/mmwr.mm7029a1
Symptoms and Signs of RSV and hMPV
RSV and hMPV illnesses manifest similarly. The most recognizable clinical syndromes are bronchiolitis Bronchiolitis Bronchiolitis is an acute viral infection of the lower respiratory tract affecting infants < 24 months and is characterized by respiratory distress, wheezing, and/or crackles. Diagnosis is... read more and pneumonia Overview of Pneumonia Pneumonia is acute inflammation of the lungs caused by infection. Initial diagnosis is usually based on chest x-ray and clinical findings. Causes, symptoms, treatment, preventive measures, and... read more .
These illnesses typically begin with upper respiratory symptoms and fever, then progress over several days to dyspnea, cough, wheezing, and/or crackles on chest auscultation. Apnea may be the initial symptom of RSV in infants < 6 months.
In healthy adults and older children, illness is usually mild and may be inapparent or manifested only as an afebrile common cold. However, severe disease may develop in the following:
Patients who are < 6 months old, older adults, or patients who are immunocompromised
Patients who have underlying cardiopulmonary or neuromuscular disorders
Diagnosis of RSV and hMPV
Characteristic symptoms and signs, particularly during the usual season or a known outbreak
Sometimes rapid antigen tests, reverse-transcription–polymerase chain reaction (RT-PCR), or viral culture (all done on nasal washings or swabs)
RSV (and possibly hMPV) infection is suspected in infants and young children with bronchiolitis or pneumonia during RSV season. Because antiviral treatment is not typically recommended, a specific laboratory diagnosis is unnecessary for patient management. However, a laboratory diagnosis may facilitate hospital infection control by allowing segregation of children infected with the same virus.
Rapid antigen tests with a high sensitivity for RSV and other respiratory viruses are available for use in children; nasal washings or swabs are used. These tests are less sensitive in adults. Viral culture may be performed. Molecular diagnostic assays such as RT-PCR have improved sensitivity and are generally available as single or multiplex assays.
Treatment of RSV and hMPV
Supportive care
Treatment of RSV and hMPV infections is supportive and includes supplemental oxygen and hydration as needed (see treatment of bronchiolitis Treatment Bronchiolitis is an acute viral infection of the lower respiratory tract affecting infants < 24 months and is characterized by respiratory distress, wheezing, and/or crackles. Diagnosis is... read more ).
Corticosteroids and bronchodilators are generally not helpful and are currently not recommended.
Antibiotics are reserved for patients with fever, evidence of pneumonia on chest x-ray, and clinical suspicion of a bacterial coinfection.
Palivizumab (monoclonal antibody to RSV) is not effective for treatment.
Inhaled ribavirin, an antiviral medication with activity against RSV, has marginal efficacy, is potentially toxic to health care professionals, and is no longer recommended except for infection in patients who are severely immunocompromised.
Numerous medications targeting viral fusion, entry, and replication for adults and infants are currently in development and in clinical trials (1 Treatment reference Respiratory syncytial virus and human metapneumovirus infections cause seasonal lower respiratory tract disease, particularly in infants and young children. Disease may be asymptomatic, mild... read more ).
Treatment reference
1. Domachowske JB, Anderson EJ, Goldstein M: The future of respiratory syncytial virus disease prevention and treatment. Infect Dis Ther 10(Suppl 1):47–60, 2021. doi: 10.1007/s40121-020-00383-6
Prevention of RSV and hMPV
Contact precautions (eg, hand washing, gloves, isolation) are important, particularly in hospitals.
Passive prophylaxis with palivizumab decreases the frequency of hospitalization for RSV in high-risk infants. It is cost-effective only for infants at high risk of hospitalization, including those with the following characteristics:
< 1 year old with hemodynamically significant congenital heart disease
< 1 year old with chronic lung disease of prematurity (gestational age < 32 weeks and 0 days with the need for oxygen therapy for at least 28 days after birth)
Born at < 29 weeks gestation and are < 1 year old at the start of RSV season
Chronic lung disease of prematurity in the second year of life and have received within 6 months of RSV season treatment with chronic corticosteroids or diuretics or have had a continued need for oxygen therapy
Prophylaxis may also be considered for
Infants in the first year of life who have anatomic pulmonary abnormalities that impair the ability to effectively clear the upper airways
Infants who have neuromuscular disorders
Children < 24 months old who have profound immunocompromise
The dose of palivizumab is 15 mg/kg IM. The first dose is given just before the usual onset of the RSV season (early November in North America). Subsequent doses are given at 1-month intervals for the duration of the RSV season (usually a total of 5 doses). Additional doses may be recommended during a prolonged RSV season or significant interseason RSV activity. (See also the American Academy of Pediatrics' updated 2014 updated guidance for palivizumab prophylaxis for infants and young children who are at increased risk of hospitalization for RSV and 2022 updated guidance on the use of palivizumab prophylaxis to prevent hospitalization from severe RSV infection during the 2022–2023 RSV season.)
In May 2023, the U.S. Food and Drug Administration approved a respiratory syncytial virus vaccine for the prevention of lower respiratory tract disease caused by RSV in people ≥ 60 years of age.
Nirsevimab, a fusion protein monoclonal antibody, and several other maternal, pediatric, and adult RSV vaccines are in development in clinical trials (1 Prevention references Respiratory syncytial virus and human metapneumovirus infections cause seasonal lower respiratory tract disease, particularly in infants and young children. Disease may be asymptomatic, mild... read more , 2 Prevention references Respiratory syncytial virus and human metapneumovirus infections cause seasonal lower respiratory tract disease, particularly in infants and young children. Disease may be asymptomatic, mild... read more ).
Prevention references
1. Hammitt LL, Dagan R, Yuan Y, et al: Nirsevimab for prevention of RSV in healthy late-preterm and term infants. N Engl J Med 386(9):837–846, 2022. doi: 10.1056/NEJMoa2110275
2. Domachowske JB, Anderson EJ, Goldstein M: The future of respiratory syncytial virus disease prevention and treatment. Infect Dis Ther 10(Suppl 1):47–60, 2021. doi: 10.1007/s40121-020-00383-6
Key Points
Respiratory syncytial virus (RSV) and human metapneumovirus usually cause a syndrome of bronchiolitis, but pneumonia may occur.
Diagnosis is usually clinical, but testing, including rapid antigen tests and molecular assays (eg, reverse-transcription–polymerase chain reaction), is available.
Give supportive treatment; corticosteroids, bronchodilators, and palivizumab are not recommended.
Inhaled ribavirin may be useful for RSV but is potentially toxic to health care professionals and is now used only in patients with severe immunocompromise.
Passive prophylaxis with palivizumab just before and during RSV season decreases the frequency of hospitalization in specific high-risk infants.
More Information
The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
American Academy of Pediatrics (AAP): Updated guidance for palivizumab prophylaxis among infants and young children at increased risk of hospitalization for respiratory syncytial virus infection (2014)
Drugs Mentioned In This Article
| Drug Name | Select Trade |
|---|---|
palivizumab |
Synagis |
ribavirin |
Copegus, Moderiba, Rebetol, RibaPak, Ribasphere, Ribasphere RibaPak, RibaTab, Virazole |
respiratory syncytial virus vaccine |
ABRYSVO, Adjuvant Suspension Component for AREXVY, AREXVY, Lyophilized Antigen Component for AREXVY |
nirsevimab |
BEYFORTUS |
