Comparison of the immunogenicity and safety of two 17D yellow fever vaccines

As part of the clinical validation process of a new working seed of a licen sed yellow fever vaccine (new working seed PV26, Stamaril(TM); Pasteur Meri eux Connaught, Lyon, France), the immunogenicity and safety of two batches of this vaccine (PM-YF) were compared with those of another commercially av ailable vaccine (Arilvax(TM); Evans Medical-Wellcome, Liverpool, United Kin gdom) in 211 healthy adults. While the geometric mean titer values at days 10-14 and day 28 after vaccination were higher in the PM-YF group, the vacc ines provided equivalent seroprotection (titers greater than or equal to 1/ 10) one month after a single vaccine dose (100% PM-YF versus 99% W-YF; P = 0.001, by one-sided equivalence test). Both vaccines were safe. There were no serious local or systemic reactions reported, nor any clinically signifi cant hepatic function abnormalities associated with the use of either vacci ne. These two 17D yellow fever vaccines from different European vaccine man ufacturers were highly immunogenic and safe, and provided equivalent seropr otection.