Adolescent HB vaccination
Canadian provinces were pioneers in establishing school-based HB vaccination programs, with British Columbia leading the way in 1992 (1). Ample evidence confirms that recombinant HB vaccine induces a robust, long-lasting immune response in preadolescents.
A remarkable prospective study conducted in Quebec City (2) monitoredanti-HB surface antigen titres for 15 years after routine vaccination
of eight- to 10-year-olds. The seropositivity rate (titre ≥10 IU/L) was 98.9% at series completion and 76.7% 15 years later.
Virtually all of those who were seronegative after 15 years responded strongly to a booster dose, indicating persistence of immune memory.
The capacity to recall an antibody response following exposure to HB virus is considered to be sufficient to protect against symptomatic disease because the long incubation period of this infection allows time for a recalled immune response to neutralize infection at an early stage. This is consistent with the observation of a 90% decline in the rate of acute HB infection among Canadians 10 to 19 years of age between 1990 and 2008 (3). Based on similar observations from around the world, no booster vaccination is currently recommended following primary HB vaccination (4). Whether protection will last life-long will require prolonged follow-up studies.