A Mathematical Model of Hepatitis A Virus Transmission and Its Application for Adult Vaccination Strategy in Korea

Abstract

Despite universal child vaccination programs and mandatory surveillance systems, the incidence rate of Hepatitis A virus (HAV) recently increased rapidly in Republic of Korea (Korea). Previous studies conducted in Korea developed mathematical models of HAV and projected the effectiveness of child vaccination

however, there were no studies done using empirical data upon introduction of the National Immunization Programs child vaccination program. In this study, we proposed an age-structured dynamic model calibrated with recent empirical data, in order to understand the transmission dynamics of HAV infection and evaluate the impact of diverse adults vaccination strategies as an application of this model. Although there were some unavoidable assumptions within the model due to lack of underlying information, the projected results fitted well with the empirical data with respect to epidemiology and anti-HAV seroprevalence. Moreover, when compared with the equivalent vaccine coverage, the results indicated that the HAV vaccination for those in their 30s were more effective than that of those in their 20s. Furthermore, when the first dose coverage is greater than 20% and the second dose coverage is at 95%, after a time of eight years, the percentage reduction of notification case is approximately 50%. Sensitivity analysis indicated that the waning rate and proportion of primary vaccine failure could be a fundamental factor in predicting the future epidemic curve of an HAV infection. The model indicated adult vaccination for 30s can be practical and effective intervention to reduce the burden of HAV in Korea.