nirsevimab
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 > 58,000 to 80,000 hospitalizations annually in the United States in children under the age of 5 years (1).
RSV is ubiquitous; almost all children are infected by age 4 years (2). 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 (3).
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.
General references
1. Centers for Disease Control and Prevention (CDC): RSV Surveillance and Research. Accessed December 11, 2023.
2. Committee on Infectious Diseases, American Academy of Pediatrics, Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH: Red Book: 2021–2024 Report of the Committee on Infectious Diseases, ed. 32, pp. 628–636, 2021. doi: 10.1542/9781610025782
3. 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 and pneumonia.
These illnesses typically begin with upper respiratory symptoms and fever and then may 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).
Corticosteroids and bronchodilators are generally not helpful and are not recommended.
Antibiotics are reserved for patients with fever, evidence of pneumonia on chest radiograph, and clinical suspicion of a bacterial coinfection.
1).
Treatment reference
1. Beaird OE, Freifeld A, Ison MG, et al: Current practices for treatment of respiratory syncytial virus and other non-influenza respiratory viruses in high-risk patient populations: A survey of institutions in the Midwestern Respiratory Virus Collaborative. Transpl Infect Dis 18(2):210-215, 2016. doi: 10.1111/tid.12510
Prevention of RSV and hMPV
Contact precautions (eg, hand washing, gloves, isolation) are important, particularly in hospitals.
interim recommendations regarding nirsevimab use amid supply limitations.) Nirsevimab
a long-acting monoclonal antibody, is recommended for the prevention of RSV in the following infants and young children (1, 2, 3, 4):
All infants < 8 months of age who are either born during or who are entering their first RSV season
Children 8 months through 19 months of age who are at increased risk of severe RSV disease and who are entering their second RSV season
Healthy newborns (ie, those who have no increased risk of severe RSV) should receive no more than 1 dose of nirsevimab. Typically, this dose is given during an infant’s first RSV season. Those born at the end of their first RSV season should receive this nirsevimab
interim recommendations regarding nirsevimab use amid supply limitations. Children who receive nirsevimab should not receive palivizumab in the same RSV season.
High-risk children 8 to 19 months of age include the following:
Children with chronic lung disease of prematurity who required medical support any time during the 6-month period before the start of the second RSV season
Children who are severely immunocompromised
Children with cystic fibrosis who have severe lung disease or whose weight-for-length is less than the 10th percentile
Children who are American Indian or Alaska Native
For eligible children, nirsevimab should be given shortly before the RSV season (typically from October through the end of March in most of the continental United States). For infants who did not receive a dose at the start of the season, a dose may be given at any time during the season.
Nirsevimab may be given before the newborn leaves the hospital and simultaneously with other childhood vaccines.
also a monoclonal antibody, decreases the frequency of hospitalization for RSV in high-risk infants (5, 6). It should be used only in situations where nirsevimab is not available.
Palivizumab is cost-effective only for infants at high risk of hospitalization, including those with the following characteristics:
Born at < 29 weeks gestation and are < 1 year old at the start of RSV season
< 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)
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
< 1 year old with hemodynamically significant congenital heart disease
Prophylaxis with palivizumab may also be considered for
Infants < 1 year old who have anatomic pulmonary abnormalities or neuromuscular disorders that impair the ability to effectively clear the upper airways
Children < 24 months old who have profound immunocompromise
Infants who were initially given palivizumabpalivizumab series.
7, 8, 9). One of the vaccines also was approved for use in pregnant people at 32 to 36 weeks gestation for the prevention of lower respiratory tract disease caused by RSV in their infant from birth through 6 months of age (10, 11).
Several maternal, pediatric, and adult RSV vaccines are in development in clinical trials.
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. Griffin MP, Yuan Y, Takas T, et al: Single-Dose Nirsevimab for Prevention of RSV in Preterm Infants. N Engl J Med 383(5):415-425, 2020. doi: 10.1056/NEJMoa1913556
3. Simões EAF, Madhi SA, Muller WJ, et al: Efficacy of nirsevimab against respiratory syncytial virus lower respiratory tract infections in preterm and term infants, and pharmacokinetic extrapolation to infants with congenital heart disease and chronic lung disease: A pooled analysis of randomised controlled trials. Lancet Child Adolesc Health 7(3):180-189, 2023. doi: 10.1016/S2352-4642(22)00321-2
4. Jones JM, Fleming-Dutra KE, Prill MM, et al: Use of nirsevimab for the prevention of respiratory syncytial virus disease among infants and young children: recommendations of the Advisory Committee on Immunization Practices–United States, 2023. MMWR Morb Mortal Wkly Rep 72(34):920-925, 2023. doi: 10.15585/mmwr.mm7234a4
5. Garegnani L, Styrmisdóttir L, Roson Rodriguez P, et al: Palivizumab for preventing severe respiratory syncytial virus (RSV) infection in children. Cochrane Database Syst Rev 11(11):CD013757, 2021. doi: 10.1002/14651858.CD013757.pub2
6. The IMpact-RSV Study Group: Palivizumab, a humanized respiratory syncytial virus monoclonal antibody, reduces hospitalization from respiratory syncytial virus infection in high-risk infants. Pediatrics 102(3):531–537, 1998.
7. Melgar M, Britton A, Roper LE, et al: Use of Respiratory Syncytial Virus Vaccines in Older Adults: Recommendations of the Advisory Committee on Immunization Practices—United States, 2023. MMWR Morb Mortal Wkly Rep 72:793–801, 2023. doi: 10.15585/mmwr.mm7229a4
8. Papi A, Ison MG, Langley JM, et al: Respiratory Syncytial Virus Prefusion F Protein Vaccine in Older Adults. N Engl J Med 388(7):595-608, 2023. doi: 10.1056/NEJMoa2209604
9. Walsh EE, Pérez Marc G, Zareba AM, et al: Efficacy and Safety of a Bivalent RSV Prefusion F Vaccine in Older Adults. N Engl J Med 388(16):1465-1477, 2023. doi: 10.1056/NEJMoa2213836
10. Kampmann B, Madhi SA, Munjal I, et al: Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants. N Engl J Med 388(16):1451-1464, 2023. doi: 10.1056/NEJMoa2216480
11. American College of Obstetricians and Gynecologists (ACOG): Practice Advisory: Maternal Respiratory Syncytial Virus Vaccination. Accessed November 27, 2023.
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, nirsevimab, and palivizumab are not recommended.
Nebulized ribavirin may be useful for RSV but is potentially toxic to health care professionals and is used only in patients with severe immunocompromise.
nirsevimab
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)
ACIP and AAP: ACIP and AAP Recommendations for Nirsevimab (2023)
