Oseltamivir can keep children with flu out of the ICU

Treatment with oseltamivir in children hospitalized with influenza helps prevent progression into a state requiring ICU admission and shorten the length of hospital stay, as shown in a US-based retrospective study.

In a cohort of children hospitalized with influenza during the 2014/2015–2022/2023 seasons, oseltamivir was associated with a 31-percent reduction in the hazard of ICU admission (adjusted hazard ratio [aHR], 0.69, 95 percent confidence interval [CI], 0.60–0.80), according to presenting author Dr Kacie Rytlewski from the University of Colorado School of Medicine in Aurora, Colorado, US. [IDWeek 2025, abstract 104]

The analysis excluded patients who received treatment the same day they were admitted to the ICU. When these patients were reclassified as not having been treated in a sensitivity analysis, the strength of the association between oseltamivir and the hazard of ICU admission increased, with an aHR of 0.30 (95 percent CI, 0.26–0.34).

Moreover, the drug’s beneficial effect on the outcome persisted regardless of treatment timing. The hazard of ICU admission was significantly lower with early (≤2 days: aHR, 0.74, 95 percent CI, 0.63–0.86; p<0.01) and late treatment (≥3 days: aHR, 0.55, 95 percent CI, 0.41–0.73; p<0.01) relative to no treatment, but there was no significant difference seen between early and late treatment (aHR, 1.34, 95 percent CI, 0.99–1.81; p<0.061), suggesting that late treatment still has value, Rytlewski said.

Shortened hospital stay

Oseltamivir treatment was also associated with an increased likelihood of being discharged, which means reduced hospitalization duration (aHR, 1.13, 95 percent CI, 1.06–1.21), the author noted.

In sensitivity analysis, however, that the benefit was only observed when treatment was given early, within 48 h (aHR, 1.15, 95 percent CI, 1.08–1.23; p<0.01). Later treatment had a null effect on shorter length of hospital stay compared with no treatment (aHR 1.08, 95 percent CI, 0.98–1.20; p=0.13).

Concerns about oseltamivir use

Prior investigations already showed that nuraminidase inhibitors such as osetalmivir were beneficial in the treatment of children hospitalized with influenza, being associated with increased survival and decreased length of hospital stay. These pieces of evidence led to the recommendation that this population be treated with oseltamivir in national guidelines by Infectious Diseases Society of America, the American Academy of Pediatrics, and Centers for Disease Control and Prevention. [Pediatrics 2013;132:e1539-e1545; Pediatrics 2021;148:e2021050417]

“Despite these recommendations, paediatric providers are still concerned about side effects and efficacy with oseltamivir use,” noted Rytlewski.

In a recent study, providers in clinical specialties such as hospital medicine, critical care, emergency medicine, and pulmonology were less likely to prescribe oseltamivir compared with infectious disease providers. Concerns raised included side effects and efficacy or benefit, and clinical factors such as illness duration (<48 or >48 h from symptom onset) were used to impact the decision to treat. [Pediatrics 2025;155:e2024069111]

The “findings [of the present study] support current national guidelines to treat children hospitalized with influenza with oseltamivir,” Rytlewski said.

For the study, Rytlewski and colleagues used data from FluSurv-NET. The primary ICU admission analysis included 6,044 children (average age 3 years, 56 percent male, 31 percent White, 49 percent with medical comorbidity), of which 4,240 received oseltamivir. The length of stay outcome analysis included 7,103 patients, of which 5,746 received oseltamivir, and the 1,059 who received treatment on the same day of ICU admission were excluded from the primary analysis.

The study was limited by its retrospective nature, the presence of COVID-19 pandemic/atypical respiratory seasons, and the potential for incomplete capture of outpatient antiviral flu testing.