Treatment of Influenza in Infants

Introduction to Treatment

The American Academy of Pediatrics recommends oseltamivir as the antiviral treatment for influenza in infants, with FDA approval for use starting at 2 weeks of age, and should be initiated as soon as possible regardless of time since symptom onset in hospitalized infants or those at high risk for complications 1, 2

All infants with suspected or confirmed influenza should be offered antiviral treatment given their high risk for complications, including hospitalized infants with suspected influenza 3, 1, 4
Infants with severe, complicated, or progressive illness should receive antiviral treatment 3, 5, 1
Any infant under 2 years of age should receive antiviral treatment as they are at increased risk of hospitalization and complications 6, 3, 5

Oseltamivir (oral suspension, 6 mg/mL concentration) is the drug of choice for infants, with dosing as follows:
Preterm infants require adjusted dosing based on postmenstrual age (gestational age + chronological age) 2

Treatment should be initiated immediately upon clinical suspicion without waiting for confirmatory testing 3, 5, 1, 4
Greatest benefit occurs when started within 48 hours of symptom onset, but treatment after 48 hours still provides benefit in infants and should be strongly offered given their high-risk status 6, 3, 4

Oseltamivir reduces risk of complications including hospitalization and death 6, 7, 3

Oseltamivir can be administered without regard to meals, though giving with food may improve gastrointestinal tolerability 6, 2
Available as commercially manufactured oral suspension (6 mg/mL concentration) 6, 3, 5

Vomiting is the most common adverse effect, occurring in approximately 5-15% of treated children 3, 5, 4
Diarrhea may occur in children <1 year of age 1, 4

Zanamivir is not recommended for infants due to limited approval and potential for bronchospasm risk 6, 1
Peramivir is only approved for children ≥2 years of age 1, 4

Current influenza strains show minimal resistance to oseltamivir, with <0.5% of influenza A (H3N2) and pH1N1 viruses showing resistance 6
Amantadine and rimantadine should not be used due to high resistance levels 6, 4

Do not delay treatment while awaiting confirmatory testing, as clinical judgment based on symptoms and local influenza activity should guide immediate treatment decisions 3, 5, 1, 4
Do not withhold treatment beyond 48 hours, as infants remain high-risk and benefit from treatment even when started later in illness course 3, 5, 1
Ensure proper weight-based dosing, as preterm infants require lower doses due to immature renal function and risk of excessive drug concentrations 2