Combination Hepatitis A and B Vaccine to Induce Immunity in Non-responders

Hepatitis B is a vaccine preventable infection which can be transmitted through occupational exposure. Approximately 15% of patients will not respond to an initial series of vaccination. Of those re-vaccinated approximately fifty percent will respond. On the basis of poor response to a third series, repeat vaccination is not recommended and non-responders are considered vulnerable to infection. Cardell studied the use of double dose combination hepatitis A and B vaccine (Twinrix) in non responders who had received four or more doses previously and found a high response rate suggesting this vaccine and dose could be effective. The investigators study seeks to duplicate the findings of Cardell, using a more strict definition of non-responder (6 or more previous doses).