Estimated impact of the national hepatitis B immunization program on acute viral hepatitis B among adolescents in Republic of Korea

OBJECTIVES: We aimed to estimate the impact of the national hepatitis B immunization program on the incidence of acute hepatitis B infection among adolescents in South Korea. METHODS: We estimated the counterfactual incidence rate of reported acute hepatitis B among adolescents from 2016 to 2020 compared to the assumption that the national hepatitis B immunization program for children had not been implemented since 1995. The impact of the national hepatitis B immunization program for adolescents was measured by estimating the absolute risk reduction and averted acute hepatitis B infections among adolescents from 2016 to 2020 attributed to the national immunization program. RESULTS: The relative risk reduction of acute hepatitis B among adolescents was estimated to be 83.5% after implementing the national hepatitis B immunization program. The incidence rate of reported acute hepatitis B infections among adolescents decreased from 0.39 to 0.06 per 100,000 person-years, and 43 acute hepatitis B infections, including 17 symptomatic cases, were averted annually from 2016 to 2020 by the national hepatitis B immunization program. CONCLUSION: The national hepatitis B immunization program for children was effective in preventing acute hepatitis B infection among adolescents in South Korea.