What is the recommended use of the RSV (Respiratory Syncytial Virus) vaccine, specifically Palivizumab (monoclonal antibody), for high-risk infants?

RSV Vaccine (Palivizumab) for High-Risk Infants

Current Landscape: Nirsevimab Has Replaced Palivizumab as First-Line

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

• Nirsevimab demonstrates 79% efficacy in preventing medically attended RSV-associated lower respiratory tract infection and requires only a single intramuscular injection before or during RSV season (typically November through March) 1

• Palivizumab is now reserved for specific situations where nirsevimab may not be available or appropriate 1

When Palivizumab Is Still Used

High-Risk Populations Requiring Palivizumab

Palivizumab remains indicated for infants born before 29 weeks, 0 days' gestation who are younger than 12 months at the start of RSV season. 2, 1, 3

Prematurity-Based Indications:

• Infants with history of premature birth (≤35 weeks gestational age) who are 6 months of age or younger at the beginning of RSV season 3
• Infants born 32 weeks 0 days through 34 weeks 6 days gestation qualify only if they have at least one of these risk factors: attend child care OR have ≥1 siblings or other children younger than 5 years living permanently in the household 2

Chronic Lung Disease (CLD/BPD):

• Infants <24 months with chronic lung disease requiring medical therapy (supplemental oxygen, bronchodilators, diuretics, or chronic corticosteroids) within 6 months before RSV season start 2, 1, 4, 3
• Children with pulmonary abnormality or neuromuscular disease that impairs ability to clear secretions from upper airways 2, 1, 5

Congenital Heart Disease (CHD):

• Infants ≤12 months with hemodynamically significant CHD receiving medication for congestive heart failure 2, 1, 4, 3
• Infants with moderate to severe pulmonary hypertension 2, 1, 4
• Infants with cyanotic heart disease (consultation with pediatric cardiologist recommended) 2, 4

Special Populations:

• Profoundly immunocompromised children <24 months during RSV season may be considered for prophylaxis 2, 4
• Children <2 years undergoing cardiac transplantation during RSV season 2, 4

Dosing and Administration

The recommended dose is 15 mg/kg body weight given intramuscularly every 30 days throughout RSV season. 2, 1, 5, 4, 3

Maximum Number of Doses:

• 5 doses maximum for infants with hemodynamically significant CHD, CLD, or birth before 32 weeks 0 days' gestation 2, 5, 4
• 3 doses maximum for infants 32 weeks 0 days through 34 weeks 6 days gestation without CHD or CLD who qualify for prophylaxis 2, 1, 4

Timing Considerations:

• First dose should be given 48-72 hours before discharge or promptly after discharge for hospitalized infants 1, 5
• If next monthly dose is due while infant is hospitalized, administer on schedule 1
• Doses should be initiated before RSV season starts and continued monthly throughout the season 2, 5

Critical Post-Surgical Dosing:

An additional 15 mg/kg dose of palivizumab must be administered as soon as medically stable after cardiopulmonary bypass surgery or extracorporeal membrane oxygenation (ECMO), as these procedures decrease serum palivizumab concentrations by 58%. 2, 1, 5, 4, 3

• After this post-operative dose, resume monthly dosing as scheduled 2, 3

Contraindications and When NOT to Use Palivizumab

Absolute Contraindications:

• Previous significant hypersensitivity reaction to palivizumab (anaphylaxis and anaphylactic shock, including fatal cases, have been reported) 3

Hemodynamically Insignificant Heart Disease (NOT Indicated):

• Secundum atrial septal defect (ASD) 1, 4
• Small ventricular septal defect (VSD) 1, 4
• Mild pulmonic stenosis 1, 4
• Uncomplicated aortic stenosis 1, 4
• Mild coarctation 1, 4
• Patent ductus arteriosus 1, 4
• Adequately corrected cardiac lesions unless still requiring CHF medication 1, 4
• Mild cardiomyopathy not receiving medical therapy 1

Other Populations NOT Requiring Routine Palivizumab:

• Down syndrome without qualifying conditions (prematurity <29 weeks, CHD, CLD, or airway clearance issues) 2, 4
• Cystic fibrosis without clinical evidence of CLD or nutritional compromise in first year of life 2, 4

Efficacy Data

Palivizumab provides a 55% overall reduction in RSV-related hospitalization in premature infants and those with chronic lung disease. 1, 6, 7

• 78% reduction in RSV hospitalization for premature infants without BPD 7
• 39% reduction for children with BPD 7
• 45% reduction in RSV-related hospitalization for infants and children with hemodynamically significant CHD 1
• Real-world hospitalization rates: 0.7-4.0% in premature infants and 0-5.5% in patients with BPD 8

Safety Profile

• Adverse events similar to placebo (11% vs 10%) 6
• Most common reactions: fever, rash, and mild transient injection site erythema 3, 6, 7
• Discontinuation for adverse events is rare (0.3%) 7
• Use with caution in children with thrombocytopenia or any coagulation disorder 3

Critical Pitfalls to Avoid

Failure to Dose After Cardiac Surgery:

The most critical error is failing to administer an additional dose after cardiac bypass surgery, which results in suboptimal protection due to 58% decrease in serum palivizumab concentration. 2, 1, 5, 4

Inappropriate Use:

• Do not use palivizumab in infants with hemodynamically insignificant heart disease 1, 5
• Do not discontinue prophylaxis prematurely before end of RSV season 1, 5

Breakthrough RSV Infection:

• If breakthrough RSV hospitalization occurs, discontinue monthly prophylaxis due to extremely low likelihood (<0.5%) of second RSV hospitalization in same season 2, 5
• This differs from earlier guidance that recommended continuing prophylaxis 1

Diagnostic Interference:

• Palivizumab may interfere with immunological-based RSV diagnostic tests such as some antigen detection-based assays 3

Limitations

• Palivizumab is NOT effective for treatment of established RSV disease 5, 3
• NOT recommended for primary asthma prevention or to reduce subsequent episodes of wheezing 1, 5

Essential Adjunctive Preventive Measures

All high-risk infants must also receive comprehensive non-pharmacologic prevention regardless of palivizumab use: 2, 1, 5

• Eliminate all tobacco smoke exposure 2, 1, 5
• Restrict high-risk infants from daycare during RSV season when feasible 2, 1, 5
• Keep infants away from crowds and situations where exposure to infected people cannot be controlled 2, 1, 5
• Practice meticulous hand hygiene 2, 1, 5
• Ensure influenza vaccination for all infants ≥6 months and their contacts 2, 1, 5
• Administer all age-appropriate immunizations on schedule (palivizumab does not interfere with routine childhood immunizations) 1
• Restrict healthcare personnel with upper respiratory tract infections from caring for high-risk patients 1

Vaccine Compatibility

• Both palivizumab and nirsevimab do not interfere with routine childhood immunizations, which should proceed on schedule 1