Comparison of the Effectiveness of Baloxavir and Oseltamivir in Outpatients With Influenza B.

This retrospective cohort study analyzed data from a Japanese health insurance database to assess the effectiveness of baloxavir (n = 4822) for preventing severe events compared with oseltamivir (n = 10,523) in patients with influenza B. The primary endpoint was hospitalization incidence (Days 2-14). The secondary endpoints included intravenous antibacterial drug use, pneumonia hospitalization, heart failure hospitalization, inhalational oxygen requirement, and use of other anti-influenza drugs. The hospitalization incidence was significantly lower with baloxavir (0.15% vs. 0.37%; risk ratio: 2.48, 95% confidence interval: 1.13-5.43). Pneumonia and additional anti-influenza therapy were also less frequent with baloxavir, thus supporting its use. Trial Registration: UMIN Clinical Trials Registry Study ID: UMIN000051382.