A Budget Impact Analysis of Reducing Viral Transmission With Baloxavir Marboxil Treatment for Seasonal Influenza in Japan

OBJECTIVES: Baloxavir marboxil (baloxavir) is an oral antiviral that rapidly stops influenza viral shedding. However, the impact of reduced viral shedding on the number of infections and the resulting budget impact are unknown. This study aimed to investigate the reduction in the total number of infections and the budget impact of baloxavir compared to neuraminidase inhibitors (NAIs) using a SEIR (susceptible, exposed, infected, recovered) model.

METHODS: The population-level SEIR model estimated the attack rates by comparing the impact of treatment ratio of baloxavir and NAIs to linking the time of infectious virus negativity discharge, using the clinical trial data on influenza viral transmission. The population was stratified into four subgroups: 1) otherwise healthy children, 2) high-risk children, 3) otherwise healthy adolescents and non-elderly adults, and 4) high-risk adolescents, high-risk adults, and the elderly. The parameters were calculated using Japanese real-world data from the 2018-2019 season, before the COVID-19 pandemic. The budget impact analysis was conducted at the total population level, incorporating the attack rates from the SEIR model.

RESULTS: The SEIR model estimated greater reductions in infections with increased baloxavir treatment. We estimated that infections decreased from 11.7 million to 9.6 million (18.3% reduction) when 10% of NAIs were replaced with baloxavir based on the 2018/2019 season. The budget impact was calculated to be a reduction of 6.0 billion JPY in influenza drug costs, 15.9 billion JPY in medical costs, and 20.7 billion JPY in labor productivity losses.

CONCLUSIONS: Baloxavir treatment may result in fewer influenza cases and could save costs of billions of JPY per influenza season from public healthcare payers’ perspective and social perspective in Japan. As influenza epidemics have been resurgent in Japan from the 2023/2024 season, we will update the results of the transmission model and the budget impact analysis to reflect the latest situation.