Universal hepatitis B vaccination in Belgium: impact on serological markers 3 and 7 years after implementation

Hepatitis B virus (HBV) can be eliminated by effective universal vaccination. In Belgium, a free-of-charge HBV vaccination programme in infants with catch-up in adolescents was introduced in 1999. To evaluate the effects in <20-year-olds, seroprotection (anti-HBs >11mIU/ml, according to the assay) and markers of infection (anti-HBc, HBsAg) were assessed in 2443 residual sera collected 7-8 years after implementation of the programme. The maximal prevalence of a solely anti-HBs seroprotective ('vaccinated') serostatus was 82 center dot 9% at age 1 year and 60 center dot 5% at age 13 years. A clear increase was found in age cohorts targeted by the campaign after a similar serosurvey conducted 4 years earlier. The prevalence of HBV infection remained unchanged at a low level (1 center dot 8% in 2006) similar to pre-vaccination data (1993-1994). We conclude that universal HBV vaccination has achieved overall high levels of vaccine-induced immunity, despite regional variations, which may give rise to pockets of susceptible young adults in the future.