HBV seroprevalence and liver fibrosis status among population born before national immunization in Southern Thailand: Findings from a health check-up program

BACKGROUND: Hepatitis B virus (HBV) infection is the leading cause of liver-related death worldwide, particularly in Asia. Patients with either current or past HBV infection are at risk of cirrhosis and hepatocellular carcinoma (HCC). Here, we investigated the HBV seroprevalence in residents of southern Thailand born before the national vaccination program. METHODS: A cross-sectional study of individuals born before the nationwide HBV vaccination program who sought check-up programs which included HBV serology and abdominal ultrasound at a tertiary care hospital in southern Thailand from 2019 to 2020 was conducted. HBV serology, cirrhosis and liver fibrosis status (determined by ultrasonography and FIB-4), and clinical notes regarding management following HBsAg+ detection were obtained. RESULTS: Of 1,690 eligible individuals, the overall prevalence of HBsAg+ and HBsAg-antiHBc+, indicating current and past HBV infections, were 2.9% and 27.8%, respectively. Among current HBV patients, 87.8% were unaware of their infection. Cirrhosis was found in 8.2%, 1.1%, and 0.3% of patients with current, past, and no HBV infection, respectively (p<0.001). One-fourth of past HBV patients had FIB-4≥1.45, which indicated indeterminate or significant liver fibrosis, which may increase the risk of HCC. CONCLUSION: The prevalence of HBsAg+ in Southern Thailand was 2.9%, and that of past infection (HBsAg-antiHBc+) was 27.8%. Patients with current and past HBV infection have an increased risk of cirrhosis and significant liver fibrosis. Most current HBV patients were unaware of their infection. Identifying patients with current and past HBV infection who are at risk for HCC and linking them to a cascade of care is necessary to reduce the burden of HBV-related liver diseases in Thailand.