Seroepidemiology of hepatitis B virus infection among adults in Singapore: a 12-year review.

We undertook a national hepatitis B seroprevalence study to assess the seroprevalence of hepatitis B virus (HBV) markers in the adult population in Singapore in 2010 and make comparisons with the seroprevalence in 1998 and 2004. The study involved residual sera from national health surveys conducted every six years since 1998. The tests for HBV markers were carried out using commercial chemiluminescent microparticle immunoassay. In 2010, the prevalence of hepatitis B surface antigen (HBsAg) among 3293 Singapore residents aged 18-79 years was 3.6% (95% confidence interval [CI] 2.9-4.2%). Hepatitis B e antigen (HBeAg) was detected in 4.2% of those who were HBsAg positive. About 22.5% (95% CI 21.1-23.9%) were positive for antibody to hepatitis B core antigen (anti-HBc). The overall population immunity to HBV, as determined by antibody to hepatitis B surface antigen (anti-HBs)≥ 10 mIU/mL, was 43.9% (95% CI 42.2-45.6%). Among young adults below 30 years of age, HBsAg prevalence (1.1%) was half that in 1998 and 2004, and in those positive for HBsAg, none was positive for HBeAg in 2010, compared to 20.8% in 1998 and 15.8% in 2004. In this age group, anti-HBc prevalence also decreased significantly from 22.1% in 2004 to 4.4% in 2010, while anti-HBs (≥ 10 mIU/mL) prevalence increased significantly from 27.9% in 1998 to 43.3% in 2010 (p<0.001). The national childhood HBV immunisation and catch-up programmes implemented in 1987 and 2001-2004, respectively, had a significant impact in reducing HBV infection and in raising the immunity of the adult population 18-29 years of age.