Management of Pediatric Influenza
Immediate Antiviral Treatment Recommendations
Initiate oseltamivir immediately for all hospitalized children with suspected influenza, children under 2 years of age, children with severe/progressive illness, and children at high risk for complications—do not delay treatment while awaiting laboratory confirmation. 1, 2, 3
Who Must Receive Treatment
- All children <2 years of age with suspected or confirmed influenza, regardless of illness severity, vaccination status, or time since symptom onset (this age group faces exceptionally high risk for complications, hospitalization, and death) 1, 2
- All hospitalized children with presumed influenza, regardless of vaccination status 1, 2
- Children with high-risk conditions including:
- Chronic pulmonary disease (including asthma) 1
- Cardiovascular disease (except hypertension alone) 1
- Renal, hepatic, hematologic (including sickle cell disease), or metabolic disorders (including diabetes) 1
- Neurologic and neurodevelopmental conditions (cerebral palsy, epilepsy, intellectual disability, muscular dystrophy, spinal cord injury) 1
- Immunosuppression (medication-induced or HIV) 1
- Morbid obesity (BMI ≥40) 1
- American Indian/Alaska Native persons 1
- Residents of nursing homes and chronic care facilities 1
When to Consider Treatment in Otherwise Healthy Children
Treatment should be considered for any otherwise healthy child with suspected influenza when:
- Treatment can be initiated within 48 hours of symptom onset 1, 2
- The child has close contact with household members <6 months of age (who cannot receive vaccine) 1, 2
- The child has close contact with household members who have high-risk conditions 1
Critical Timing and Testing Considerations
Start treatment immediately based on clinical suspicion during influenza season—the greatest benefit occurs within 48 hours of symptom onset, but treatment should still be provided even after 48 hours in high-risk children. 1, 2
Do Not Delay for Testing
- Antiviral treatment should be started as soon as possible and must not be delayed while waiting for definitive influenza test results 1, 2, 3
- Rapid antigen tests have low sensitivity (particularly for H1N1) and should not be used to rule out influenza 1
- Negative rapid antigen tests should not be used to make treatment or infection-control decisions 1, 2
- Clinical judgment based on underlying conditions, disease severity, time since symptom onset, and local influenza activity should guide treatment decisions 1
Treatment Beyond 48 Hours
- Earlier treatment provides more optimal clinical responses 1
- Treatment after 48 hours in children with moderate-to-severe disease or progressive disease is likely to provide some benefit 1
- High-risk children (especially those <2 years) benefit from treatment even when started later in the illness course 1, 2
Recommended Antiviral Medications and Dosing
First-Line Agent: Oseltamivir (Oral)
Oseltamivir is the antiviral drug of choice for managing influenza in children, available as capsules and oral suspension (6 mg/mL concentration). 1, 2, 3, 4
Treatment Dosing (5 days duration):
Infants 0-8 months (term):
Infants 9-11 months:
Children ≥12 months (weight-based):
Adolescents ≥13 years and adults:
Special Considerations for Preterm Infants:
- <38 weeks postmenstrual age: 1.0 mg/kg per dose twice daily 1, 2
- 38-40 weeks postmenstrual age: 1.5 mg/kg per dose twice daily 1, 2
40 weeks postmenstrual age: 3.0 mg/kg per dose twice daily 1, 2
Administration:
- Can be given with or without food, though administration with meals may improve gastrointestinal tolerability 1, 2, 4
- If commercial suspension unavailable, pharmacies can compound from capsules to achieve 6 mg/mL concentration 1, 2
- FDA-approved for infants as young as 2 weeks of age 1, 2
Alternative Agents
Zanamivir (Inhaled):
- Acceptable alternative for children ≥7 years (treatment) or ≥5 years (prophylaxis) 1, 2
- 10 mg (two 5-mg inhalations) twice daily for 5 days 1
- More difficult to administer than oseltamivir 1, 2
- Should not be used in children with chronic respiratory disease 1, 2
Peramivir (Intravenous):
- Approved for children ≥2 years with acute uncomplicated influenza who have been symptomatic ≤2 days 2
- No data available for chemoprophylaxis use 1
Baloxavir (Oral):
- Approved for treatment and post-exposure prophylaxis in patients ≥5 years 5
- Single-dose administration 5
- Should not be coadministered with dairy products, calcium-fortified beverages, or polyvalent cation-containing products (antacids, calcium, iron, magnesium, selenium, zinc) 5
- Weight-based dosing: <20 kg: 2 mg/kg; 20-<80 kg: 40 mg; ≥80 kg: 80 mg 5
Adamantanes (Amantadine/Rimantadine):
Clinical Benefits of Treatment
Timely oseltamivir treatment provides measurable benefits:
- Reduces illness duration by approximately 17.6-29.9 hours (1-1.5 days) 1, 2, 3
- Decreases risk of acute otitis media by 34-44% 1, 2, 3
- Reduces antibiotic prescriptions by approximately 10% 3
- Lowers risk of complications including hospitalization and death 1, 6, 7
- Accelerates fever resolution and return to normal activities 2
Antiviral Resistance Monitoring
- During recent influenza seasons, >99% of influenza A(H1N1)pdm09, A(H3N2), and B viruses tested were susceptible to oseltamivir, peramivir, and zanamivir 1, 3
- Resistance rates remain <0.5% for most circulating strains 3
- Decreased susceptibility to baloxavir has been reported in Japan where use is more common 1
- High levels of resistance to amantadine and rimantadine persist—these drugs should not be used unless resistance patterns change 1, 2
- Continuous population-based assessment is conducted by the CDC 1
Chemoprophylaxis for Close Contacts
Indications for Post-Exposure Prophylaxis
Chemoprophylaxis is recommended for:
- Children at high risk for whom influenza vaccine is contraindicated 1
- Children at high risk during the 2 weeks after influenza immunization (before protective antibodies develop) 1
- Unimmunized family members or healthcare personnel with ongoing close exposure to:
- Post-exposure prophylaxis for family members and close contacts of infected persons who are at high risk of complications 1
- Immunocompromised children as supplement to vaccination (who may not respond adequately to vaccine) 1
- Institutional outbreak control for unimmunized staff and children in closed settings with high-risk children 1
- When circulating strains are not matched with vaccine strains 1
Critical Timing for Prophylaxis
- Must be initiated within 48 hours of exposure for optimal effectiveness 1, 8
- If >48 hours have elapsed, do not give prophylaxis—instead, educate patient/family to initiate full-dose treatment immediately if symptoms develop 8
Chemoprophylaxis Dosing (10 days duration for post-exposure):
Oseltamivir:
- Infants 3-8 months: 3 mg/kg once daily 1, 4
- Infants 9-11 months: 3.5 mg/kg once daily 1, 4
- Children ≥12 months:
- Not recommended for infants <3 months unless situation judged critical 1, 4
Zanamivir:
- Children ≥5 years: 10 mg (two 5-mg inhalations) once daily 1
Baloxavir:
- Single dose within 48 hours of exposure for patients ≥12 years 1
- Demonstrated 2% infection rate vs 13% with placebo in household contacts 1
Duration of Prophylaxis
- Post-exposure prophylaxis: 10 days after most recent exposure 8, 4
- Seasonal/community outbreak prophylaxis: Up to 6 weeks 4
- Immunocompromised patients: May continue up to 12 weeks 4
Critical Prophylaxis Considerations
- Chemoprophylaxis is NOT a substitute for vaccination—influenza vaccine should always be offered when not contraindicated 1, 8
- Use lower once-daily dosing for prophylaxis; do not use prophylaxis dosing for treatment of symptomatic children 1
- If a child on prophylaxis becomes symptomatic, immediately switch to full treatment dosing (twice daily) without waiting for laboratory confirmation 1, 8
- LAIV effectiveness will be decreased in children receiving oseltamivir or other neuraminidase inhibitors (but IIV is not affected) 1
- Inform families that risk of influenza is lowered but not eliminated while taking prophylaxis, and susceptibility returns when medication is discontinued 1
Supportive Care Measures
- Evaluate need for oxygen therapy to maintain SaO₂ >92% 2
- Ensure adequate hydration; consider intravenous fluids if dehydration present 2
- Monitor for warning signs requiring immediate attention:
Secondary Bacterial Infection
- Do not routinely initiate antibiotics 2
- Add antibiotics only if evidence of secondary bacterial infection develops 2
- First-line antibiotics for children <12 years: co-amoxiclav 5 mL of 125/31 suspension three times daily 2
- For penicillin allergy: clarithromycin 62.5 mg twice daily (ages 1-2 years) 2
Infection Control for Household Contacts
- Limit exposure to other household members, especially high-risk individuals 2
- Practice good hand hygiene for all household members 2
- Consider prophylactic oseltamivir for high-risk household contacts if exposed within 48 hours 2, 8
- Implement cough etiquette and use of face masks 9
Common Pitfalls to Avoid
- Do not withhold treatment while awaiting laboratory confirmation in high-risk or severely ill children 2, 3
- Do not rely on negative rapid antigen tests to rule out influenza or make treatment decisions 1, 2, 3
- Do not use amantadine or rimantadine due to widespread resistance 1, 2, 3
- Do not use prophylaxis dosing (once daily) for treatment of symptomatic children—use full treatment dosing (twice daily) 1
- Do not give baloxavir with dairy products or polyvalent cation-containing products 5
- Do not substitute chemoprophylaxis for vaccination 1, 8
- Do not delay treatment beyond 48 hours in high-risk children, but still treat even if >48 hours have passed 1, 2
Adverse Effects and Safety
Oseltamivir:
- Vomiting occurs in approximately 5-15% of treated patients but is generally mild and transient 1, 2, 3
- Diarrhea may occur in children <1 year 2
- Despite historical concerns, controlled clinical trials and ongoing surveillance have failed to establish a link between oseltamivir and neurologic or psychiatric events 2, 3
- Gastrointestinal effects are less likely when taken with food 2
Zanamivir:
Renal Dose Adjustment
For patients with renal insufficiency (creatinine clearance 10-30 mL/min):