Safety and Immunogenicity of a Tetravalent Live-attenuated Dengue Vaccine in Flavivirus Naive Children

A similar formulation was tested in an open-label trial in seven flavivirus-naive Thai children between the ages of 6 and 9 years. The vaccine was well -tolerated without serious adverse events (SAEs) or alert clinical laboratory values. Solicited symptoms were more frequent after dose 1; the symptoms occurring in at least four of seven subjects were pain, redness, and swelling at the injection site, headache, and temperature ≥ 37.5°C. Three subjects had DENV-4 vaccine viremia, in two cases associated with transient fever. Thirty days after dose 1, DENV-2 and DENV-4 responses predominated, with 50% of the cohort seroconverting to each type with geometric mean titers (GMTs) of 16 and 30, respectively. Thirty days after dose 2, 100% of the cohort had seroconverted to all DENV serotypes, with an observed boost in GMT for each DENV serotype (DENV-1, from less than 10 to 55; DENV-2, from 16 to 475; DENV-3, from 6 to 350; DENV-4, from 30 to 171). 12 Herein, we report the reactogenicity, safety and immunogenicity profile of the DENV vaccine candidate administered as two doses to flavivirus-naive Thai subjects aged 12 to 15 months. These subjects are being followed to assess long-term persistence of anti-DENV neutralizing antibodies and evaluate the safety and reactogenicity of a booster dose administered 3 years after primary vaccination (to be published separately).