The first combined vaccine against hepatitis A and B: an overview.

Hepatitis A and B infections are prevalent world-wide and are a significant cause of morbidity and mortality. A vaccine providing dual protection against hepatitis A and B is now available (Twinrix, SmithKline Beecham Biologicals). Six pivotal vaccine trials, involving 843 healthy adults, aged between 17 and 60 years and vaccinated following a 0, 1, 6 month schedule are discussed. At month 2 more than 99% of the vaccinees were seropositive for anti-HAV and 84% were protected against hepatitis B. The third dose induced a 12-fold increase in geometric mean titres (GMTs) to 5404 mIU/ml. One month after completion of the vaccination course nearly all vaccinees had protective titres against hepatitis B with a GMT of 4818 mIU/ml. Long term follow-up data until month 48 is available for two studies. At month 48 all 129 vaccinees sampled were still positive for anti-HAV antibodies and > 95% were still protected against hepatitis B. The combined hepatitis A and B vaccine Twinrix proves to be consistently safe, well tolerated and highly immunogenic and compares well with serological responses reached with monovalent vaccines. This combined hepatitis A and B vaccine offers more convenience, potentially better compliance and lower administration costs.