Immunogenicity of WHO-17D and Brazilian 17DD yellow fever vaccines: a randomized trial.
| Autor: | Camacho LA; Escola Nacional de Saúde Pública, Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, RJ, Brazil. luiz.camacho@ensp.fiocruz.br, Freire Mda S, Leal Mda L, Aguiar SG, Nascimento JP, Iguchi T, Lozana Jde A, Farias RH |
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| Jazyk: | angličtina |
| Zdroj: | Revista de saude publica [Rev Saude Publica] 2004 Oct; Vol. 38 (5), pp. 671-8. Date of Electronic Publication: 2004 Oct 18. |
| DOI: | 10.1590/s0034-89102004000500009 |
| Abstrakt: | Objective: To compare the immunogenicity of three yellow fever vaccines from WHO-17D and Brazilian 17DD substrains (different seed-lots). Methods: An equivalence trial was carried out involving 1,087 adults in Rio de Janeiro. Vaccines produced by Bio-Manguinhos, Fiocruz (Rio de Janeiro, Brazil) were administered following standardized procedures adapted to allow blocked randomized allocation of participants to coded vaccine types (double-blind). Neutralizing yellow fever antibody titters were compared in pre- and post-immunization serum samples. Equivalence was defined as a difference of no more than five percentage points in seroconversion rates, and ratio between Geometric Mean Titters (GMT) higher than 0.67. Results: Seroconversion rates were 98% or higher among subjects previously seronegative, and 90% or more of the total cohort of vaccinees, including those previously seropositive. Differences in seroconversion ranged from -0.05% to -3.02%. The intensity of the immune response was also very similar across vaccines: 14.5 to 18.6 IU/mL. GMT ratios ranged from 0.78 to 0.93. Taking the placebo group into account, the vaccines explained 93% of seroconversion. Viremia was detected in 2.7% of vaccinated subjects from Day 3 to Day 7. Conclusions: The equivalent immunogenicity of yellow fever vaccines from the 17D and 17DD substrains was demonstrated for the first time in placebo-controlled double-blind randomized trial. The study completed the clinical validation process of a new vaccine seed-lot, provided evidence for use of alternative attenuated virus substrains in vaccine production for a major manufacturer, and for the utilization of the 17DD vaccine in other countries. |
| Databáze: | MEDLINE |
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