The DENGVAC study: Preliminary findings on the immunogenicity of the TAK-003 dengue vaccine

OBJECTIVES: This study was designed to assess the safety and immunogenicity of the first dose of the TAK-003 dengue vaccine. The immune response profiles of vaccinated participants were compared among individuals who experienced or did not experience natural dengue infection in the past or as an acute infection. METHODS: In this single-centre prospective observational study, subjects were stratified into three groups: Group1-dengue seronegative; Group2-dengue seropositive; Group3-acute dengue infection. The assessments of vaccine-induced immunogenicity included: DENV-2 neutralizing antibodies, monocyte and dendritic cell (DC) phenotyping and T-cell response at baseline (T0) and 3 months (T3) post-vaccination (Group1 and 2) or post-infection (Group3). RESULTS: One hundred fifty subjects were enrolled at T0, and among them 80 subjects (median age 38 years, 50% male) were also evaluated at T3. Anti-DENV-2 neutralizing antibodies increased 26.9- and 9.19-fold in Group1 and 2, and 3.06-fold in Group3. Group1 showed increased monocytes and Group3 had reduced myeloid-DC and higher plasmacytoid-DC. Group1 and 2 exhibited DENV CD4 MP-induced T-cell responses similar to those observed in Group3. Notably, Group1 demonstrated a significantly greater T-cell response to the DENV CD8 MP than Group3. CONCLUSIONS: Preliminary data showed that TAK-003 vaccine is safe and immunogenic. The first vaccine dose elicits a functional antibody and a robust T-cell response. Further analyses on the current cohort are ongoing.