- Design
- Population-based surveillance cohort, time-dependent Cox models
- Population
- 6,044 children <18 hospitalised with laboratory-confirmed influenza, US
- Primary outcome
- Time from symptom onset to ICU admission
- Effect
- aHR 0.69 (95% CI 0.60–0.80); discharge aHR 1.13 (1.06–1.21)
This cohort used US population-based surveillance (FluSurv-NET) across 13 states from 2014–15 to 2022–23, excluding 2020–21. It included about 6,000 children hospitalised with laboratory-confirmed influenza whose symptom onset date was known — median age 3, half with a comorbidity, most commonly asthma. Oseltamivir was modelled as a time-dependent exposure to reduce immortal-time bias.
Treatment was associated with a lower hazard of ICU admission (aHR 0.69, a 31% reduction) and faster discharge (aHR for discharge 1.13). The authors note that antiviral use in hospitalised children has been declining in recent seasons.
This is observational, but it is large and designed to avoid the commonest biases in such studies, and it supports existing recommendations to treat all hospitalised children with suspected or confirmed influenza as early as possible, regardless of how long they have been ill.
- Start oseltamivir promptly in every child admitted with suspected or confirmed influenza.
- Do not wait for test results before starting treatment in a hospitalised child.
- Treat even if symptoms began more than 48 hours earlier.
- Adjust the dose for weight and for kidney function.
- Prioritise children under five and those with asthma or other chronic conditions.
Why it matters
Antiviral use in hospitalised children has been falling, despite evidence that it keeps them out of intensive care.
Don't overread it
This was observational; the association is strong but residual confounding cannot be excluded.
The statistics, in plain English
An aHR of 0.69 (0.60–0.80) means treated children moved to the ICU at about 69% of the rate of untreated children at any given time. Treating oseltamivir as time-dependent stops children who received it later from being wrongly counted as treated from day one.
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