Background & Aims: Hepatitis B virus (HBV) infection poses a global public health threat. HBV vaccination has proven highly effective in preventing the infection; however, its long-term impact on the general population has not been addressed. We conducted analysis to determine the total and changing burden of chronic HBV infection and evaluate the serological status between vaccinated and unvaccinated in Taiwan. Methods: Participants in "The Taiwanese Survey on Prevalence of Hyperglycemia, Hyperlipidemia and Hypertension" in 2002 (n = 6602), and 4088 with follow-up survey in 2007 were included. HBsAg (including titers), anti-HBs, anti-HBc, HBeAg, anti-HBe, HBV genotypes and viral loads were assayed. Prevalence and evolving patterns of these seromarkers was compared between vaccinated and unvaccinated cohorts and predictors of persistent HBsAg positivity and negativity were examined. Results: The overall prevalence of chronic HBV infection was 13·7% (95% CI, 12.9% to 14.5%) and about two thirds had past exposure (anti-HBc: 68·46%) in 2002. The vaccinated cohort tended to have lower prevalence of HBsAg and anti-HBc, and a higher proportion of anti-HBs and HBeAg positivity, genotype C and high viral load. The majority (85·42%) were consistently HBsAg negative while 12·65% were consistently positive, and 8·98% achieved seroclearance in a five-year period. In the vaccinated cohort, no subjects had acquired new exposure and became HBsAg positive, and only one (0.54%) cleared HBsAg, demonstrating the durability of vaccination through teenage and young adulthood. Conclusions: This comprehensive, population-representative-sur vey shows that 20 years after universal vaccination, the backlog still composed a substantial burden of chronic HBV infections in Taiwan.
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