Do all children under 2 with influenza require treatment with Tamiflu (oseltamivir)?

Tamiflu (Oseltamivir) Treatment for Children Under 2 with Influenza

Not all children under 2 years with influenza require treatment with Tamiflu (oseltamivir), but treatment should be offered to those who are hospitalized, have severe/complicated disease, or are at high risk of complications. 1, 2

Treatment Recommendations by Clinical Scenario

Children Under 2 Who Should Receive Oseltamivir:

• Children hospitalized with suspected or confirmed influenza 1, 2
• Children with severe, complicated, or progressive illness attributable to influenza, regardless of duration of symptoms 1, 2
• Children at high risk of complications from influenza 1, 2
• Children whose siblings or household contacts either are younger than 6 months or have underlying medical conditions that predispose them to complications 2

Children Under 2 Where Treatment May Be Considered:

• Otherwise healthy children with influenza when a decrease in duration of clinical symptoms is warranted 2
• Treatment should ideally be initiated within 48 hours of symptom onset for maximum benefit, though treatment after 48 hours may still provide benefit in moderate-to-severe or progressive disease 1

Rationale for Treatment in Children Under 2

• Children younger than 2 years are at increased risk of hospitalization and complications from influenza 1
• The FDA has approved oseltamivir for treatment of influenza in infants as young as 2 weeks of age 1, 3
• Timely oseltamivir treatment can reduce the risks of complications, including hospitalization and death 1
• In children with laboratory-confirmed influenza, oseltamivir can reduce the median duration of illness by 36 hours (26%) 1

Dosing for Children Under 2

• For term infants 0-8 months: 3 mg/kg/dose twice daily for 5 days 1
• For infants 9-11 months: 3.5 mg/kg/dose twice daily for 5 days 1
• For preterm infants, dosing is based on postmenstrual age (gestational age + chronological age) 1:
  • <38 weeks' postmenstrual age: 1.0 mg/kg/dose orally twice daily
  • 38-40 weeks' postmenstrual age: 1.5 mg/kg/dose orally twice daily

  • 40 weeks' postmenstrual age: 3.0 mg/kg/dose orally twice daily

Important Clinical Considerations

• Treatment should be initiated as early as possible for optimal outcomes 1, 2
• Oseltamivir is available as a liquid formulation (6 mg/mL) 1
• The most common side effect is vomiting (occurring in approximately 5% of treated patients) 1
• Administration with food may improve gastrointestinal tolerability 1
• Despite FDA approval, oseltamivir is not recommended for infants younger than 3 months unless the situation is judged critical, due to limited safety and efficacy data in this age group 1

Monitoring for Antiviral Resistance

• Continuous monitoring of resistance patterns is important as resistance to oseltamivir can emerge 1
• Current data show low levels of resistance to oseltamivir among circulating influenza strains 1

Common Pitfalls to Avoid

• Delaying treatment while waiting for laboratory confirmation - treatment should be initiated empirically in high-risk children 1, 2
• Undertreating high-risk children - studies show that antiviral prescribing is suboptimal, with only 37% of children under 2 years with influenza receiving antiviral treatment 1
• Using rapid antigen tests alone for diagnosis - these have lower sensitivity (10-70%) compared to molecular tests (86-100%) 4
• Forgetting that vaccination remains the best prevention strategy for influenza 5, 6

In summary, while not all children under 2 with influenza require oseltamivir, treatment should be strongly considered for those who are hospitalized, have severe disease, or are at high risk of complications, as this age group is particularly vulnerable to influenza-related complications.