Oseltamivir was linked to fewer ICU admissions and shorter stays in children hospitalised with influenza

Design

Population-based surveillance cohort, time-dependent exposure, adjusted Cox models

Population

6,044 US children hospitalised with laboratory-confirmed influenza, 2014–2023

Primary outcome

Time from symptom onset to ICU admission

Effect

ICU admission aHR 0.69 (0.60–0.80); discharge aHR 1.13 (1.06–1.21)

This cohort used US population-based influenza hospitalisation surveillance across 13 states from 2014–15 to 2022–23, excluding 2020–21. It included 6,044 children under 18 with laboratory-confirmed influenza and a known symptom onset date for the ICU analysis; 70.2% received oseltamivir. Median age was 3, and 49% had a comorbidity, most commonly asthma. Treatment was modelled as a time-dependent exposure, which avoids crediting the drug for children who had already escaped the ICU before receiving it.

After adjustment, oseltamivir was associated with a 31% lower hazard of ICU admission (aHR 0.69, 95% CI 0.60–0.80) and a higher rate of discharge, meaning shorter stays (aHR 1.13, 1.06–1.21).

This is observational, so unmeasured differences between treated and untreated children may remain. But it addresses the main biases of earlier studies and its findings are consistent with current recommendations to treat every child admitted with influenza as early as possible, at a time when antiviral prescribing in this group has been falling.

• Treat every child admitted with suspected or confirmed influenza with oseltamivir as early as possible.
• Do not withhold treatment because a child is already in hospital or past 48 hours of symptoms.
• Children with asthma or other comorbidities made up half this cohort and are a priority.
• Audit antiviral prescribing for admitted children each influenza season; use has been declining.
• Combine antiviral treatment with influenza vaccination advice for the family at discharge.

Why it matters

It strengthens the case for antiviral treatment just as its use in admitted children is slipping.

Don't overread it

This is observational; it cannot fully exclude differences between children who were and were not treated.

The statistics, in plain English

An adjusted hazard ratio of 0.69 means about 31% lower risk of ICU admission at any point in time among treated children, after accounting for measured differences. Treating oseltamivir as time-dependent counts each child as untreated until the drug is given, which removes a common bias that inflates benefit.

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