“…From published data [Jilg et al, , 1988Heijtink et al, 1985;Papaevangelou et al, 1985;Weber et al, 1985;Stevens et al, 1987;Crovari et al, 1988;Taylor et al, 1988;Marinho et al, 1988;Shaw et al, 1989;West, 1989;Zajac et al, 1989;Dahl-Hansen et al, 1990;Hadler, 1990;Street et al, 1990;Dentico et al, 1991;Renzulli et al, 1992;Oates et al, 1993;Treadwell et al, 1993;Wood et al, 1993;Chiaramonte et al, 1996;Pride et al, 1998;Jones et al, 1999;Heijtink et al, 2000] and national vaccination guidelines [UK Department of Health Advisory Group on Hepatitis, 1993; Morgan, 1995], we anticipated that the protection rate in healthy normal younger adults would be 90 to 95% with the standard three-dose regimen of current single antigen vaccines, and since this study allowed all ages to be recruited with randomisation strati®ed for age group (above or below 40 years) to ensure balance, we anticipated the overall Recombivax-HB protection rate would be at the lower end of the above range.…”