Respiratory Syncytial Virus Infection in the Pediatric Population

Respiratory syncytial virus (RSV) is one of the many pathogens that cause respiratory infections. Although the symptoms of infection are usually mild and self-limited, in some patients the infection may be severe. Infection with RSV can take a variety of forms, ranging from a mild upper respiratory tract infection to severe, life-threatening acute respiratory failure.¹

RSV belongs to the pneumovirus genus and its genetic material is in the form of RNA. The pathogen has a special affinity for the epithelium of the respiratory tract.

Cells infected with it combine into larger structures, creating syncytia. The impaired movement of the cilia that line the epithelium of the respiratory tract and the overproduction of mucus can make patients feel short of breath and have difficulty breathing.

It is spread by airborne droplets and by direct contact. High infectivity means that even a short contact with an infected person may result in infection.²

RSV is the most common cause of respiratory infections in newborns and infants.¹ For healthy children, RSV infection is not dangerous and is usually mild. Infections with RSV in premature babies, children with immunodeficiencies and with some birth defects, especially the respiratory system and the heart muscle, can cause worse outcomes.

The infection can lead to impaired lung function and problems such as chronic obstructive pulmonary disease. As a prophylaxis, it is recommended to breastfeed for at least 6 months, and to avoid contact with tobacco smoke and people presenting symptoms of respiratory tract infection. In infants at risk of severe infection, it is additionally recommended to administer palivizumab, which is a monoclonal anti-RSV antibody.³

Palivizumab’s mechanism of action exhibits neutralizing and fusion-inhibitory activity against RSV. Palivizumab binds to the fusion glycoprotein of RSV, which prevents RSV binding and uptake by host cellular receptors.⁴

Palivizumab is used for prevention of serious lower respiratory tract disease caused by RSV in pediatric patients with a history of premature birth (≤35 weeks gestational age) and who are ≤6 months at the beginning of RSV season; pediatric patients with bronchopulmonary dysplasia (BPD) who required medical treatment within the previous 6 months and who are ≤24 months at the beginning of RSV season or pediatric patients with hemodynamically significant congenital heart disease (CHD) and who are ≤24 months at the beginning of RSV season.⁵

The American Academy of Pediatrics (AAP 2014) recommends RSV prophylaxis with palivizumab during RSV season for:⁶

• Infants born at ≤28 weeks 6 days gestational age and <12 months at the start of RSV season.
• Infants <12 months of age with chronic lung disease (CLD) of prematurity.
• Infants ≤12 months of age with hemodynamically significant CHD.
• Infants and children <24 months of age with CLD of prematurity necessitating medical therapy (eg, supplemental oxygen, bronchodilator, diuretic, or chronic steroid therapy) within 6 months prior to the beginning of RSV season.

AAP also suggests that palivizumab prophylaxis may be considered in the following circumstances:⁶

• Infants <12 months of age with congenital airway abnormality or neuromuscular disorder that decreases the ability to manage airway secretions.
• Infants <12 months of age with cystic fibrosis with clinical evidence of CLD and/or nutritional compromise.
• Children <24 months with cystic fibrosis with severe lung disease (previous hospitalization for pulmonary exacerbation in the first year of life or abnormalities on chest radiography or chest computed tomography that persist when stable) or weight for length less than the 10th percentile.
• Infants and children <24 months who are profoundly immunocompromised.
• Infants and children <24 months undergoing cardiac transplantation during RSV season.

Palivizumab is administered as an intramuscular injection for infants and children <24 months with the dose 15 mg/kg once monthly throughout RSV season. The first dose should be administered prior to commencement of RSV season.⁵

If child is hospitalized at the start of RSV season, palivizumab should be given 48 to 72 hours before discharge or promptly after discharge per AAP 2014 guidelines. The AAP recommends a maximum 5 doses per season and if hospitalization occurs for breakthrough RSV infection, monthly prophylaxis should be discontinued for the remainder of that season.⁶

For cardiopulmonary bypass patients, the dose of 15 mg/kg should be administered as soon as possible after cardiopulmonary bypass procedure or at the conclusion of extracorporeal membrane oxygenation, even if <1 month from previous dose. A 58% decrease in palivizumab serum concentrations has been noted after cardiopulmonary bypass.⁶

Children with comorbidities may be more severely infected with RSV. These patients may develop acute respiratory failure and often require hospital treatment.

The serious complications include secondary bacterial pneumonia and otitis media. In this group of patients, the initial infection of the upper respiratory tract often spreads to the lower respiratory tract, causing bronchitis and pneumonia. Treatment of RSV infection, as with other acute respiratory viral diseases, is symptomatic.

References

1. CDC. Respiratory Syncytial Virus Infection (RSV). RSV in Infants and Young Children. Accessed October 20, 2022. https://www.cdc.gov/rsv/high-risk/infants-young-children.html.
2. Cohen JI, Wilson E. Antiviral Chemotherapy, Excluding Antiretroviral Drugs. In: Loscalzo J, Fauci A, Kasper D, Hauser S, Longo D, Jameson J. eds. Harrison's Principles of Internal Medicine, 21e. McGraw Hill; 2022. Accessed October 20, 2022. https://accesspharmacy-m hmedical-com.roosevelt.idm.oclc.org/content.aspx?bookid=3095&sectionid=263965262
3. Alansari K, Toaimah FH, Almatar DH, El Tatawy LA, Davidson BL, Qusad MIM. Monoclonal antibody treatment of RSV bronchiolitis in young infants: a randomized trial. Pediatrics. 2019;143(3):e20182308.
4. Synagis (palivizumab) [prescribing information]. Gaithersburg, MD: MedImmune, LLC; May 2017.
5. Synagis (palivizumab) [product monograph]. St-Laurent, Quebec, Canada: AbbVie Corporation; March 2018.
6. American Academy of Pediatrics (AAP). Committee on Infectious Diseases and Bronchiolitis Guidelines Committee. Updated guidance for palivizumab prophylaxis among infants and young children at increased risk of hospitalization for respiratory syncytial virus infection. Pediatrics. 2014;134(2):415-420. doi: 10.1542/peds.2014-1665.
7. American Academy of Pediatrics (AAP). AAP Publications Reaffirmed. Pediatrics. 2019;144(2). pii: e20191767. doi: 10.1542/peds.2019-1767.