Immunogenicity of WHO-17D and Brazilian 17DD yellow fever vaccines: a randomized trial

Abstract

ObjectiveTo 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. ConclusionsThe 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. $ %Rev Saúde Pública 2004;38(5):671-8 www.fsp.usp.br/rsp Immunogenicity of yellow fever vaccines Camacho LAB et al Resumo Objetivo Comparar a imunogenicidade de três vacinas contra febre amarela ) das subcepas WHO-17D e 17DD brasileira (diferentes lotes-semente

Efficacy and Duration of Immunity after Yellow Fever Vaccination: Systematic Review on the Need for a Booster Every 10 Years

“…10,11,23 Protective immunity after YF vaccination. Twelve studies in 11 articles 6,10,[25][26][27][28][29][30][31][32][33] addressed the efficacy of YF vaccine in terms of immunogenicity (Table 3). Seroconversion rates were consistently 90% in 9 of 10 studies.…”

Reactogenicity of yellow fever vaccines in a randomized, placebo-controlled trial

“…3 The frequency of signs and symptoms on the injection site reported in the literature varied from nil to 39%. 5,7,[9][10][11]14,15,17,18,20,22,23 In all studies, pain on the site of injection was the most frequently reported local adverse event.…”

“…3 A physician was available for intervention on acute health problems during immunization procedures. Participants with liver enzymes levels twice or more the upper normal limit were referred for further investigation.…”

The yellow fever 17D virus as a platform for new live attenuated vaccines

“…Concordantly, the generation of neutralizing antibodies is a hallmark of protective antiviral immunity against the YF17D virus. 27,28 Neutralizing antibodies directed against structural protein E is believed to be the most critical in terms of protection. 29,30 These neutralizing antibodies may persist for 40 y post vaccination, which exhibits the ability of the virus to elicit an efficient immune response that will result in a long-lived humoral response.…”