Comparison of the reactogenicity and immunogenicity of a two injection combined high-dose hepatitis A and hepatitis B vaccine to those of Twinrix (TM)

Twinrix(TM) (SmithKline Beecham Biologicals) is a combined hepatitis A and B vaccine licensed with a three-dose schedule. A two-dose combined hepatiti s A and B vaccine would facilitate immunisation programs. In this prospecti ve study, 100 healthy adults, aged between 18 and 40, were enrolled. A firs t group of 50 was given a high-dose vaccine at month 0 and 6. A second grou p of 50 received Twinrix(TM) at month 0, 1 and 6. The reactogenicity was assessed after each vaccine dose. There were no seve re local adverse events. Seven severe systemic reactions occurred, of which five were fatigue, one was headache and one consist in gastrointestinal sy mptoms. They all resolved during the 4-day follow-up period. One serious ge neral adverse event was reported, but was clearly unrelated to the vaccine. Thus, both vaccines were well tolerated. The immunogenicity was evaluated by testing for anti-HBs and anti-HAV antib odies. Seroconversion rates and geometric mean titres (GMTs) were compared. At month 7, the anti-HAV GMTs were higher in the high-dose group than in t he Twinrix(TM) group and, inversely, the anti-HBs GMTs were slightly higher in the Twinrix(TM) group than in the high-dose group. At month 7, all subj ects in both groups were positive for anti-HAV. All subjects in the high-do se group and 97.6% subjects in the Twinrix(TM) group had seroconverted for anti-HBs. Therefore, it can be concluded that with two injections of the hi gh-dose hepatitis A and B vaccine, 6 months apart, a similar immune respons e can be obtained as induced with three doses of Twinrix(TM) at months 0, 1 and 6. (C) 2000 Elsevier Science Ltd. All rights reserved.