Comparative clinical study of a new 17D thermostable yellow fever vaccine.

The immunogenicity and the safety of a new heat-stable 17D yellow fever vaccine have been assessed in a randomized comparative study by reference to a non-stabilized vaccine preparation. Seronegative adults were used and 115 and 143 were given the heat-stable and the non-stabilized vaccine, respectively. Fifty two days after the immunization, haemagglutination inhibiting antibodies were found in 77.6 and 73.9% of the vaccinees, neutralizing antibodies in 99.3 and 100% of them. The percentage of seroconversion and the geometric mean of antibody titres were not significantly different. No complaints or adverse reactions in association with the vaccines were recorded. This study demonstrates the high immunogenicity of this new stabilized vaccine whose stability has already been proven.