Oseltamivir Linked to Lower ICU Risk in Hospitalized Children

Key Takeaways

• In children hospitalized with laboratory-confirmed influenza in the FluSurv-NET cohort, oseltamivir use was associated with significantly lower ICU admission risk.
• The lower ICU association also remained significant when oseltamivir started after the usual early window, including beyond 5 days after symptom onset.
• Most children received oseltamivir, and 22.7% started treatment before hospital admission.
• Oseltamivir use was also associated with shorter hospitalization and a 13% higher likelihood of discharge.

Hospitalized children with influenza often arrive several days after symptom onset, leaving uncertainty about whether antiviral benefit extends beyond the conventional 48-hour window. That question is especially relevant in pediatric inpatients, where illness severity and timing of presentation do not always mirror outpatient treatment assumptions. Investigators in JAMA Pediatrics examined whether oseltamivir use was associated with intensive care unit (ICU) admission and hospital length of stay in children admitted with confirmed influenza.

In a retrospective FluSurv-NET cohort reported in a JAMA Pediatrics analysis of oseltamivir outcomes in hospitalized children with influenza, investigators evaluated admissions from the 2014-2015 through 2022-2023 influenza seasons and excluded the 2020-2021 season. After exclusions, the primary ICU analysis included 6,044 children with laboratory-confirmed influenza, of whom 4,240 (70.2%) received oseltamivir; the secondary length-of-stay analysis included a separate, overlapping cohort of 7,103 children, of whom 5,746 (80.9%) received oseltamivir. Among the 7,103 children in the LOS cohort, 56% were boys, and the median age was 3 years with an interquartile range of 1 to 7 years. Investigators compared outcomes by receipt of oseltamivir, focusing on ICU admission and hospital length of stay.

Overall, 80.9% of children in the LOS cohort received oseltamivir, and 22.7% started treatment before hospital admission. In adjusted analyses of the ICU cohort, oseltamivir use was associated with lower risk of ICU admission, with an adjusted hazard ratio of 0.69 (95% CI, 0.6-0.8). The authors also reported that the lower ICU association remained significant when treatment began later in the illness course.

In the timing-specific ICU findings, adjusted hazard ratios for ICU admission were 0.74 (95% CI, 0.63-0.86) when treatment began within 2 days of symptom onset, 0.55 (95% CI, 0.41-0.73) at 3 or more days, and 0.41 (95% CI, 0.22-0.77) beyond 5 days. Oseltamivir use was also associated with shorter hospitalization in the LOS cohort, with average stays of 3.33 days versus 3.72 days and an adjusted hazard for discharge of 1.13 (95% CI, 1.06-1.21). The timing pattern suggested that the observed ICU association was not confined to the usual early-treatment window.

Because this was a retrospective observational cohort, the reported relationships should be interpreted as associations rather than causal effects. Within those bounds, similar patterns were reported across age groups and among children with obesity, asthma, and neurologic conditions. The investigators in JAMA Pediatrics concluded that oseltamivir use among children hospitalized with laboratory-confirmed influenza was associated with lower ICU admission risk and shorter hospitalization, including when treatment began later in illness. Their conclusion emphasized the observed inpatient pattern in hospitalized children with influenza.

Clinician Questions

Which hospitalized children with influenza were included in the oseltamivir cohort analysis?

The study used two overlapping cohorts drawn from FluSurv-NET across the 2014-2015 through 2022-2023 seasons, with the 2020-2021 season excluded. The primary ICU analysis included 6,044 children with laboratory-confirmed influenza (70.2% treated with oseltamivir); the secondary length-of-stay analysis included 7,103 children (80.9% treated). In the LOS cohort, 56% were boys, and the median age was 3 years with an interquartile range of 1 to 7 years.

Did the reported oseltamivir association in hospitalized children extend beyond the usual 48-hour treatment window?

The investigators reported lower ICU admission risk not only when oseltamivir began within 2 days of symptom onset but also when it began 3 or more days later and even more than 5 days after symptom onset.

What inpatient outcomes besides ICU admission were compared with oseltamivir use in children hospitalized with influenza?

Investigators also compared hospital length of stay and discharge timing in the 7,103-patient LOS cohort, and they reported shorter hospitalization with oseltamivir use along with a higher adjusted hazard for discharge.