Efficacy of the nationwide hepatitis B infant vaccination program in Taiwan.

BACKGROUND

Taiwan launched a nationwide infant vaccination program for hepatitis B (HB) in 1984.

OBJECTIVES

This study evaluated the seroprevalence of hepatitis B virus (HBV) and the incidence of high alanine aminotransferase (ALT) level among young adults prior to, during, and since the introduction of the nationwide HBV vaccination program.

STUDY DESIGN

Researchers recruited 101,584 freshmen (male:female=1.114:1; mean age, 18.5±0.5 years) from 21 universities between 1995 and 2009 (birth cohorts 1977-1991) in Taiwan, testing for serum hepatitis B surface antigens (HBsAg), hepatitis e antigens (HBeAg), antibodies against HBsAg (anti-HBs), and liver function tests, including ALT and aspartate aminotransferase (AST).

RESULTS

The results showed that the prevalence of HBsAg decreased significantly from 14.3% in 1995 to 1.1% in 2009 and the seroprevalence of HBeAg decreased significantly from 5.9% in 1995 to 0.3% in 2009. Seroconversion to anti-HBs maintained a steady rate above 50% between 1995 and 2007, but declined considerably to 36.6% and 36.4% in 2008 and 2009, respectively. Subject with HBeAg seropositivity was in 43.94% of HBV carriers. Double seronegativity for HBsAg and anti-HBs was observed in 2007 (47.8%), 2008 (62.3%), and 2009 (62.5%). High ALT level was observed in 5.74% of the subjects, particular among HBV-carriers (16.5% of HBV carrier vs. 5.0% of non-HBV carrier; ORs, 3.733; 95% CIs, 3.463-4.023, p<0.0001). Subjects with high ALT level were significantly positively associated with HBeAg (10.5% of HBeAg seropositive vs. 1.9% of HBeAg seronegative; ORs, 6.195; 95%CI, 5.629-6.818; p<0.0001). Male subjects were more easily infected by HBV than female subjects were (HBsAg, ORs, 1.355, 95% CI, 1.283-1.431; HBeAg, ORs, 1.324, 95% CI, 1.218-1.439, p<0.0001), and significantly more male subjects had high ALT levels than female subjects did (ORs, 4.087; 95% CI, 3.819-4.375, p<0.0001).

CONCLUSIONS

The mass vaccination program successfully reduced the HBV carrier rate and prevalence of chronic hepatitis B in Taiwan. However, the low percentage of anti-HBV in 2008 and 2009 remains unresolved.