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RSV—Hospitalization, Seasonality, and Pathophysiology

All infants are at risk for RSV lower respiratory tract disease¹

What is RSV?

RSV is a common, highly contagious respiratory virus, the transmission of which occurs through the nasopharyngeal or conjunctival mucosa with respiratory secretions from infected individuals—mostly other children, older siblings, and other family members.²⁻⁴ Although most of the time RSV will cause mild cold-like symptoms, we cannot predict which infants will develop RSV lower respiratory tract disease.¹

RSV incidence and hospitalization rate in infants

RSV is the leading cause of hospitalization in infants under 12 months.⁵*
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2 out of 3 infants will be infected
with RSV by age 1⁶
Infants younger than 1 icon
Infants younger than 1 year are on average
 16x more likely to be hospitalized due to RSV than for influenza⁷†
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Among children hospitalized due to RSV:
~75% were born at full term with no
underlying conditions1,8,9‡
RSV, respiratory syncytial virus.

*Based on leading primary diagnosis (RSV bronchiolitis, Oct 2015-Dec 2019, rank 1, 165,930 cases [9.3%])
†Based on data between 1993 and 2008 (routine recommendation for influenza vaccines in infants 6 months and older began in 2004).7,10
‡These data based on infants born April 2016 to February 2020 in the MarketScan Commercial (644,116), MarketScan Medicaid (1,025,286), and Optum Clinformatics (460,426) data sets; data October 2014 to April 2015 among 1,176 RSV-hospitalized infants aged younger than 12 months; data based on surveillance conducted in 2,149 hospitalized infants from October-March during the years 2000 through 2005.

Learn about RSV seasonality

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RSV is seasonal, with infections peaking at certain times throughout the year.4,11 A typical RSV season runs roughly from Fall through Spring, with some exceptions, such as in Florida, where the RSV season may start earlier.¹² Epidemiology monitoring can identify research when local RSV seasons begin.

One common misperception is that an infant born before the RSV season is better protected against the virus than one born during it. However, infants born during the season are exposed to the virus for less time than those born before it. As a result, the number of RSV-hospitalized infants born in season vs before the season is roughly equal.13*

*Based on a 2019 UK study of the number of hospitalized infants born in-season (Oct-Mar: 48%) and born before the season (Apr-Sept: 50%).

RSV pathophysiology—see how RSV symptoms progress*

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At Days 1 and 2

Droplets containing RSV from infected contact enter infant’s nasopharynx. There is usually no manifestation of symptoms at this point.¹⁴

At Days 3 Through 5

Nasopharyngeal cells are sloughed and may be aspirated, carrying RSV to lower respiratory tract cells.¹⁴ Symptoms can include congestion, runny nose, fever, irritability, and poor feeding.

At Days 6 Through 8

RSV-infected epithelial cells can travel deeper into the infant's lungs, infecting the bronchioles and alveoli, causing bronchiolitis and/or pneumonia.¹⁴ Symptoms can include cough, excess phlegm, rapid/difficult breathing, wheezing and/or grunting noises, nasal flaring, and abnormal chest movement when breathing.

Ultimately, 2 to 3 out of every 100 infants with RSV infection may need to be hospitalized. Those who are hospitalized may require supportive care such as oxygen, intubation, and/or mechanical ventilation.¹⁵
*This is one example of progression, which can vary in each individual infant.

Take a deeper dive into RSV

Article

Quality of life burden on United States infants and caregivers due to lower respiratory tract infection and adjusting for selective testing

A pilot prospective observational study estimating the quality of life (QoL) for otherwise healthy term US infants with RSV-LRTI and their caregivers.
Read article
Article

Infants admitted to US intensive care units for RSV infection during the 2022 seasonal peak

A surveillance study of 600 infants across 39 hospitals requiring intensive care for RSV infection found that most were delivered full-term and previously healthy.
Read article
Article

Optimal site of care for administration of extended half-life respiratory syncytial virus (RSV) antibodies to infants in the United States (US)

A study to assess the time from birth hospitalization discharge to the first outpatient visit among US infants in order to determine optimal site of administration for the extended half-life antibody.
Read article
RSV-LRTI, respiratory syncytial virus lower respiratory tract infection.
Woman with infant image

Power to Help Prevent RSV Disease

Learn how Beyfortus® (nirsevimab-alip) is the first and only long-acting antibody indicated for the prevention of RSV lower respiratory tract disease in term and preterm infants¹⁶
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Demonstrated Safety and Efficacy Profile¹⁶

Explore Clinical Data
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Want to Know More About Beyfortus?

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Indication

Beyfortus is indicated for the prevention of respiratory syncytial virus (RSV) lower respiratory tract disease in:

  • Neonates and infants born during or entering their first RSV season.
  • Children up to 24 months of age who remain vulnerable to severe RSV disease through their second RSV season.

Important safety information

Contraindication

Beyfortus is contraindicated in infants and children with a history of serious hypersensitivity reactions, including anaphylaxis, to nirsevimab-alip or to any of the excipients.

Warnings and Precautions

  • Hypersensitivity Reactions Including Anaphylaxis: Serious hypersensitivity reactions have been reported following Beyfortus administration. These reactions included urticaria, dyspnea, cyanosis, and/or hypotonia. Anaphylaxis has been observed with human immunoglobulin G1 (IgG1) monoclonal antibodies. If signs and symptoms of anaphylaxis or other clinically significant hypersensitivity reactions occur, initiate appropriate treatment.
  • Use in Individuals with Clinically Significant Bleeding Disorders: As with other IM injections, Beyfortus should be given with caution to infants and children with thrombocytopenia, any coagulation disorder or to individuals on anticoagulation therapy.

Most common adverse reactions with Beyfortus were rash (0.9%) and injection site reactions (0.3%).

Please see full Prescribing Information.

Click here to learn more about Sanofi’s commitment to fighting counterfeit drugs.

References: 1. Arriola CS, Kim L, Langley G, et al. Estimated burden of community-onset respiratory virus-associated hospitalizations among children aged <2 years in the United States, 2014-15. J Pediatric Infect Dis Soc. 2020;9(5):587-595. 2. Piedimonte G, Perez MK. Respiratory syncytial virus infection and bronchiolitis. Pediatr Rev. 2014;35(12):519-530. 3. Schweitzer JW, Justice NA. Respiratory syncytial virus infection. StatPearls [Internet]. 2021. 4. Yamin D, Jones FK, DeVincenzo JP, et al. Vaccination strategies against respiratory syncytial virus. Proc Natl Acad Sci U S A. 2016;113(46):13239-13244. 5. Suh M, Movva N, Jiang X, et al. Respiratory syncytial virus is the leading cause of United States infant hospitalizations, 2009-2019: a study of the national (nationwide) inpatient sample. J Infect Dis. 2022;226(suppl 2):S154-S163. 6. Glezen WP, Taber LH, Frank AL, Kasel JA. Risk of primary infection and reinfection with respiratory syncytial virus. Am J Dis Child. 1986;140(6):543-546. 7. Zhou H, Thompson WW, Viboud CG, et al. Hospitalizations associated with influenza and respiratory syncytial virus in the United States, 1993-2008. Clin Infect Dis. 2012;54(10):1427-1436. 8. Gantenberg JR, van Aalst R, Zimmerman N, et al. Medically attended illness due to respiratory syncytial virus infection among infants born in the United States between 2016 and 2020. J Infect Dis. 2022;226(suppl 2):S164-S174. 9. Hall CB, Weinberg GA, Blumkin AK, et al. Respiratory syncytial virus-associated hospitalizations among children less than 24 months of age. Pediatrics. 2013;132(2):e341-e348. 10. Harper SA, Fukuda K, Uyeki TM, et al. Prevention and Control of Influenza Recommendations of the Advisory Committee on Immunization Practices (ACIP). Centers for Disease Control and Prevention; 2004. Accessed September 5, 2023. https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5306a1.htm 11. Obando-Pacheco P, Justicia-Grande AJ, Rivero-Calle I, et al. Respiratory syncytial virus seasonality: a global overview. J Infect Dis. 2018;217(9):1356-1364. 12. RSV surveillance & research. Centers for Disease Control and Prevention. July 17, 2023. Accessed August 12, 2023. https://www.cdc.gov/rsv/research/index.html 13. Reeves RM, Hardelid P, Panagiotopoulos N, Minaji M, Warburton F, Pebody R. Burden of hospital admissions caused by respiratory syncytial virus (RSV) in infants in England: A data linkage modelling study. J Infect. 2019;78:468-475. 14. Meissner CH. Viral bronchiolitis in children. N Engl J Med. 2016;374:62-72. 15. RSV in infants and young children. Centers for Disease Control and Prevention. August 4, 2023. Accessed August 30, 2023. https://www.cdc.gov/rsv/high-risk/infants-young-children.html 16. Beyfortus (nirsevimab-alip). Prescribing Information. Sanofi.