What is the current recommendation for Respiratory Syncytial Virus (RSV) prevention in infants?

Current Recommendations for RSV Prevention in Infants

All infants under 8 months of age born during or entering their first RSV season should receive nirsevimab (a single-dose monoclonal antibody), which has replaced palivizumab as the primary prevention strategy for most infants. 1

First-Line Prevention: Nirsevimab

Nirsevimab is now the preferred agent for RSV prevention in infants, offering significant advantages over the older palivizumab regimen. 1

Who Should Receive Nirsevimab:

• All infants younger than 8 months who are born during or entering their first RSV season 1
• Children aged 8-19 months at increased risk for severe RSV disease entering their second RSV season, including those with:
  • Chronic lung disease requiring medical therapy 1
  • Hemodynamically significant congenital heart disease 1
  • Severe immunocompromise 1
  • Cystic fibrosis with manifestations of severe lung disease 1

Nirsevimab Efficacy:

The evidence supporting nirsevimab is robust, demonstrating 79% efficacy in preventing medically attended RSV-associated lower respiratory tract infection in pooled phase 2b and 3 trials. 1 This represents a substantial improvement in protection compared to historical controls and addresses the limitation that approximately 79% of infants hospitalized with RSV have no underlying medical conditions. 1

Administration:

• Single intramuscular injection given shortly before or during RSV season (typically November through March) 1
• Dosing is weight-based, eliminating the need for monthly injections required with palivizumab 1

Alternative: Maternal RSV Vaccination

Pregnant individuals may receive RSVpreF vaccine (Abrysvo) as a one-time dose at 32-36 weeks' gestation for prevention of RSV disease in infants under 6 months of age. 2 However, either maternal vaccination OR infant nirsevimab is recommended—not both for most infants. 2

When Palivizumab Remains Relevant

Palivizumab is now reserved for specific situations where nirsevimab may not be available or appropriate. 3, 2

High-Risk Groups for Palivizumab (if nirsevimab unavailable):

• Infants born before 29 weeks, 0 days' gestation who are younger than 12 months at RSV season start 3, 2, 4
• Infants under 24 months with chronic lung disease requiring medical therapy (oxygen, bronchodilators, diuretics, corticosteroids) within 6 months before RSV season 1, 3, 4
• Infants under 24 months with hemodynamically significant congenital heart disease, including:
  • Those receiving medication for congestive heart failure 1, 3
  • Moderate-to-severe pulmonary hypertension 1, 3
  • Cyanotic heart disease 1, 3

Palivizumab Dosing:

• 15 mg/kg intramuscularly monthly throughout RSV season 1, 3, 4
• Maximum 5 doses for infants with chronic lung disease, congenital heart disease, or born before 32 weeks' gestation 1
• Maximum 3 doses for infants 32-34 weeks, 6 days' gestation with risk factors (daycare attendance or siblings under 5 years in household) 1, 3

Special Palivizumab Considerations:

• Additional dose required after cardiopulmonary bypass (15 mg/kg as soon as medically stable), as bypass decreases serum concentrations by 58% 1, 3, 4
• Continue monthly dosing even with breakthrough RSV infection, as multiple RSV strains may co-circulate 1, 3
• First dose 48-72 hours before hospital discharge or promptly after discharge for eligible hospitalized infants 1, 3

Who Should NOT Receive Palivizumab:

• Infants with hemodynamically insignificant heart disease (small VSD, secundum ASD, mild pulmonic stenosis, uncomplicated aortic stenosis, mild coarctation, patent ductus arteriosus) 1, 3
• Infants with adequately corrected cardiac lesions unless requiring ongoing heart failure medication 1, 3
• Infants with mild cardiomyopathy not receiving medical therapy 1, 3
• Infants with cystic fibrosis (insufficient evidence for routine use) 1, 3

Essential Non-Pharmacologic Prevention Measures

These measures remain critical regardless of immunoprophylaxis status:

• Eliminate tobacco smoke exposure in all infants, especially high-risk infants 1, 3
• Restrict high-risk infants from daycare during RSV season when feasible 1, 3
• Avoid crowds and exposure to infected individuals 1, 3
• Practice meticulous hand hygiene 3, 5
• Ensure influenza vaccination for all infants ≥6 months and their contacts, plus all age-appropriate immunizations 1, 3
• Restrict healthcare personnel with respiratory infections from caring for high-risk patients 3

Common Pitfalls to Avoid:

• Failing to administer additional palivizumab dose after cardiac bypass surgery 1, 3
• Inappropriately prescribing palivizumab for hemodynamically insignificant heart disease 1, 3
• Discontinuing prophylaxis prematurely before RSV season ends 1, 3
• Administering both maternal RSV vaccine and infant nirsevimab when only one is needed 2
• Neglecting general preventive measures while relying solely on pharmacologic prophylaxis 1, 3

Key Distinction Between Current and Historical Recommendations:

The 2023 CDC/ACIP guidelines represent a paradigm shift from the 2009 AAP recommendations. 1 Nirsevimab is now recommended for ALL infants under 8 months entering their first RSV season, not just high-risk groups. 1 This universal approach addresses the reality that most RSV hospitalizations occur in previously healthy term infants without underlying conditions. 1