Tamiflu for Post-Exposure Prophylaxis in Children
Yes, Tamiflu (oseltamivir) is appropriate for a child who has been in close contact with someone with influenza, using weight-based dosing once daily for 10 days, ideally initiated within 48 hours of exposure. 1
Prophylaxis Dosing by Weight
The American Academy of Pediatrics recommends the following once-daily dosing for 10 days after exposure 1, 2:
- ≤15 kg (≤33 lb): 30 mg once daily 1
- >15-23 kg (>33-51 lb): 45 mg once daily 1
- >23-40 kg (>51-88 lb): 60 mg once daily 1
- >40 kg (>88 lb): 75 mg once daily 1
For infants 3-8 months old, the dose is 3 mg/kg once daily, though prophylaxis is not recommended for infants <3 months unless the situation is judged critical 1.
Timing and Effectiveness
Prophylaxis should be initiated within 48 hours of exposure to the infected individual for maximum effectiveness. 1, 3 Randomized placebo-controlled studies demonstrated that oseltamivir chemoprophylaxis was efficacious when administered to household contacts after a family member had laboratory-confirmed influenza 1.
The FDA has established safety and efficacy for prophylaxis in children 1 year to 17 years old based on post-exposure household prophylaxis trials 4. For children 1-12 years, this is supported by a randomized, open-label trial where pediatric subjects received weight-based dosing once daily for 10 days 4.
Who Should Receive Prophylaxis
Prioritize prophylaxis for children who are at high risk of influenza complications (those with chronic cardiac, pulmonary, renal, hepatic, hematologic, metabolic disorders including diabetes, or immunosuppression) 1.
Additionally, consider prophylaxis for otherwise healthy children who have close contact with high-risk individuals, particularly infants <6 months who cannot be vaccinated 1, 5.
Administration Considerations
Oseltamivir can be administered with or without food, though giving it with meals may improve gastrointestinal tolerability and reduce nausea, which occurs in approximately 10% of patients 3, 6. The oral suspension formulation (6 mg/mL concentration) should be used for children who cannot swallow capsules 2.
Important Clinical Pitfalls to Avoid
Do not use oseltamivir within 48 hours before or for 14 days after live attenuated influenza vaccine (LAIV), as the antiviral may interfere with vaccine effectiveness. 6 This is critical timing to remember when coordinating prophylaxis with vaccination schedules.
Ensure accurate weight-based dosing rather than relying on age alone, as suboptimal dosing may result from age-based estimates 6. Always verify the child's current weight to avoid dosing errors 2.
Do not delay prophylaxis while waiting for laboratory confirmation of influenza in the index case during influenza season, as clinical judgment is sufficient to initiate therapy and early initiation is critical for effectiveness 6.
For children with renal impairment (creatinine clearance 10-30 mL/min), reduce the prophylaxis dose to once every other day or adjust based on creatinine clearance 1.
Relationship to Vaccination
While annual influenza vaccination remains the primary prevention strategy, prophylaxis serves as an important adjunct, particularly for high-risk children who have not yet been immunized or during the 2-week period after vaccination before protective immunity develops 1, 7, 5.