Updated Burden and Long‐Term Projections of Chronic Hepatitis B and C in Japan: A Nationwide Markov Modeling Study

AIM: Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections remain major causes of liver-related morbidity and mortality worldwide. Although Japan has implemented nationwide screening and treatment programs for decades, updated nationwide estimates and long-term projections are limited. We aimed to estimate the number of carriers and patients in Japan in 2020 and to project through 2050. METHODS: The carriers were classified into six categories: undiagnosed carriers, patients in care, diagnosed but not linked to care, new infections, cured, and deceased. Multiple nationwide data sources-including the National Database of Health Insurance Claims (NDB), public statistics, clinical information, and large-scale blood donor screening data-were integrated to estimate the size of each category. The Markov model incorporating treatment status and liver disease progression was used to simulate annual changes from 2021 to 2050. RESULTS: In 2020, the total estimated number of carriers and patients was 1,104,406-1,424,420 (532,159-618,684, aged ≤ 69 years), including HBV: 923,893-940,647 (454,167-461,408, ≤ 69 years) and HCV: 180,513-483,773 (77,992-157,276, ≤ 69 years). Diagnosis and treatment rates exceeded WHO 2030 targets for HBV (95% and 83%-84%; 94% and 99%-100%, ≤ 69 years) and approached targets for HCV (82%-93% and 78%-100%; 75%-88% and 98%-100%, ≤ 69 years). Under current conditions, HCV infections are projected to decline to < 20,000 by 2050, whereas HBV will decrease more gradually to 200,000. CONCLUSIONS: The chronic HBV and HCV burden in Japan declined markedly, particularly for HCV, reflecting progress in prevention, diagnosis, and treatment and offering a model for hepatitis elimination.