Immunity to hepatitis A and B persists for at least 15 years after immunisation of adolescents with a combined hepatitis A and B vaccine.

•2- and 3-dose combined hepatitis A and B vaccination imparts immunity for ≥15 years.•All subjects remained seropositive for anti-HAV; 81% were protected for anti-HBs.•One-month post-challenge, all except one subject in the 3-dose group showed a robust anamnestic response.•High anamnestic response suggests no need for booster dosing for ≥15 years.