Antiviral Regimen for Prophylaxis in Children (1-12 years) Oseltamivir and Zanamivir are most effective antivirals for chemoprophylaxis in children. Dosage of Oseltamivir for prophylaxis: Dose is prescribed according to the age of children. • ≤15 kg: oseltamivir 30 mg PO once daily for 7 days • >15 to 23 kg: oseltamivir 45 mg PO once daily for 7 days • >23 to 40 kg: oseltamivir 60 mg PO once daily for 7 days • >40 kg: oseltamivir 75 mg PO once daily for 7 days Dosage of Zanamivir for prophylaxis: • aged ≥5 y: 10 mg (two 5-mg inhalations) inhaled PO once daily for 7 days.