Obesity in Recovery From Influenza-Like Illness and Effectiveness of Oseltamivir

Background: Results from observational studies have shown that obesity has a mild to moderate association with influenza-like illness (ILI) severity and hospitalization risk. Using data from the ALIC⁴E Randomized Clinical Trial (RCT), this study investigated the relationship between obesity and ILI severity, time to recovery, and oseltamivir effectiveness in the obese population. Methods: A total of 2622 adults (≥ 18 years old) from the ALIC⁴E RCT were categorized by body mass index (BMI) into under/normal weight (BMI < 25 kg/m²), overweight (BMI ≥ 25 kg/m² and < 30 kg/m²), and obesity (BMI ≥ 30 kg/m²). ILI symptom severity, time to recovery, and oseltamivir effectiveness were assessed across these weight groups. Results: At presentation, ILI symptom severity was not different between weight groups. However, time to recovery was longer for obese patients compared to under/normal weight patients, with adjusted HR 0.88 (95% CI 0.79–0.99). The mean time to recovery was 6.6 days (95% CI 6.0–7.1) for obese patients, 6.2 days (95% CI 5.8–6.6) for overweight, and 5.7 days (95% CI 5.4–6.1) for under/normal weight patients. Obese patients had similar benefits from oseltamivir treatment compared to under/normal weight patients, with an average of 0.8 days gained from oseltamivir (95% CI 0.7–1) and 0.5 days (95% CI 0.4–0.7), respectively. Conclusions: ILI symptom severity at presentation was equally distributed between the three weight groups. However, their time to recovery was approximately 1 day longer compared to under/normal weight patients. The effectiveness of oseltamivir appears to be similar between the two groups.