A pair of new studies detail the benefits of antiviral drugs for flu patients, one linking oseltamivir with lower odds of death, shorter hospital stays, and lower rates of readmission, and the other suggesting that the novel drug onradivir, similar to oseltamivir, speeds symptom relief.
Oseltamivir cuts death in hospitalized patients
Hospitalized flu patients given the antiviral drug oseltamivir (Tamiflu) are less likely to die in the hospital, be released from the hospital sooner, and have lower odds of readmission than those who receive only supportive care, suggests a target-trial emulation study published today in JAMA Network Open.
Canadian researchers used observational data to track outcomes among 11,073 adults (7,632 who received oseltamivir within 2 days after admission and 3,441 controls) at 30 hospitals in Ontario from January 2015 to June 2023. The average patient age was 72.6 years, and 52.3% were women, and the median number of treatment days was 5. Follow-up was 30 days after hospital release.
The findings of this study support current guidelines that recommend oseltamivir treatment for patients admitted to hospital with influenza; clinical trials should be conducted to generate better quality evidence.
"Current guidelines recommend oseltamivir treatment for all patients hospitalized with influenza, but this guidance is based on suboptimal evidence," the researchers wrote. "Based on the suboptimal evidence, there continues to be equipoise resulting in low adherence to guideline recommendations on oseltamivir treatment for patients hospitalized with severe influenza."
The median hospital length of stay was 4.4 (2.4 to 7.7) days and 4.9 (2.6 to 9.6) days in the oseltamivir and supportive care groups, respectively. In the hospital, 3.5% of oseltamivir recipients and 4.9% in the supportive care group died, for an adjusted risk difference of -1.8%.
The oseltamivir group was also more likely to be released from the hospital alive (adjusted subdistribution hazard ratio, 1.20). After release, 8.5% of oseltamivir recipients and 9.8% of supportive care patients were readmitted to the hospital, for an adjusted risk difference of -1.5%.
"The findings of this study support current guidelines that recommend oseltamivir treatment for patients admitted to hospital with influenza; clinical trials should be conducted to generate better quality evidence," the study authors concluded.
Two drugs linked to faster symptom relief
For a randomized, controlled phase 3 trial published late last week in The Lancet Respiratory Medicine, researchers in China compared the efficacy and safety of the novel oral antiviral onradivir in adult influenza A virus (AIV) patients at 68 sites assigned to a 5-day course of the study drug, oseltamivir, or placebo. Patients received 600 milligrams (mg) onradivir tablets once daily, 75 mg oseltamivir capsules twice daily, or placebo.
From May 2022 to May 2023, 750 patients were enrolled; 48 of them tested negative for IAV, for an intention-to-treat infection (ITTI) population of 702 participants (349 in the onradivir group, 177 in the oseltamivir group, and 176 in the placebo group.
At a time when reduced susceptibility to antiviral drugs is a growing concern, this study indicates that onradivir could be an alternative antiviral option or a candidate for use in combination with other antiviral agents for uncomplicated IAV infection.
The median time to alleviation of symptoms (TTAS) in the onradivir group was significantly shorter than that of placebo recipients (38.8 vs 63.4 hours; difference, -24.5 hours; hazard ratio [HR], 1.53) and comparable to that of the oseltamivir group (42.2 hours; HR, 1.12).
Adverse events occurred in 67% of 373 onradivir recipients, 55% of 189 in the placebo group, and 47% of 188 in the oseltamivir group. While diarrhea was more common in the onradivir group (49%) than in the placebo (23%) or oseltamivir (15%) groups, most cases were grade 1 or 2, lasted a median of 2 days, and resolved without medication.
"Onradivir has similar curative efficacy to oseltamivir for acute, uncomplicated influenza infections in adult patients, with an acceptable safety profile," the authors concluded. "At a time when reduced susceptibility to antiviral drugs is a growing concern, this study indicates that onradivir could be an alternative antiviral option or a candidate for use in combination with other antiviral agents for uncomplicated IAV infection."
