ABSTRACT 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.
Tanaka et al. (Sat,) studied this question.