Chronic hepatitis B infection (defined as sustained detection of hepatitis B virus [HBV] surface antigen [HBsAg] protein in serum) is a leading cause of cirrhosis, hepatocellular carcinoma and liver-related deaths. A situation analysis carried out by the Swiss Federal Office of Public Health estimated the HBsAg prevalence in Switzerland to be 0.53% (95% CI: 0.32-0.89%) in 2015 (~44,000 cases). A lower prevalence of chronic HBV in the younger generation and the adoption of universal coverage in the first year of life are expected to decrease the burden of HBV; however, a number of people in key populations (including migrants) remain undiagnosed and untreated, and infected individuals remain at risk of progressing to cirrhosis, hepatocellular carcinoma and death. Our primary objective was to examine the current and estimate the future disease burden of HBV in Switzerland and the impact of migration. The secondary objective was to estimate the impact of changing future treatment numbers.
A modelling study was performed using an existing, validated model (PRoGReSs Model) applied to the Swiss context. Model inputs were selected through a literature search and expert consensus. Population data from the Federal Statistical Office were used alongside prevalence data from the Polaris Observatory to estimate the number of HBV infections among people born abroad. The PRoGReSs Model was populated with and calibrated to the available data and what-if scenarios were developed to explore the impact of intervention on the future burden of disease. A Monte Carlo simulation was used to estimate 95% uncertainty intervals (95% UIs).
In 2020, there were an estimated 50,100 (95% UI: 47,500-55,000) HBsAg+ cases among people born abroad. Among people born in Switzerland, there were approximately 62,700 (UI: 58,900-68,400) total HBV infections (0.72% [UI: 0.68-0.79%] prevalence). Prevalence among infants and children under the age of 5 were both <0.1%. By 2030, prevalence of HBV is expected to decrease, although morbidity and mortality will increase. Increasing diagnosis (90%) and treatment (80% of those eligible) to meet the global health sector strategy on viral hepatitis programme targets could prevent 120 cases of hepatocellular carcinoma and 120 liver-related deaths.
Thanks to the historical vaccination programmes and the continued rollout of universal 3-dose coverage in the first year of life, Switzerland is expected to exceed the global health sector strategy targets for the reduction of incidence. While overall prevalence is decreasing, the current diagnosis and treatment levels remain below global health sector strategy targets.