Dengue vaccine: Global development update.

The first licensed dengue vaccine, CYD-TDV (Dengvaxia®), has received regulatory approval in a number of countries. However, this vaccine has some limitations. Its efficacy against DENV2 was consistently lower than other serotypes. Protective efficacy also depended on prior dengue sero-status of the vaccinees. Lower efficacy was observed in children with < 9 years old and dengue-na?ve individuals. More importantly, risk of hospitalization and severe dengue was increased in the youngest vaccine recipients (2-5 years) compared to controls. Thus, the quest of a better vaccine candidate continues. There are two live-attenuated vaccine candidates currently testing in phase III trial including DENVax, developed by US CDC and Inviragen (now licensed to Takeda) and TV003/TV005, constructed by US NIAID. In addition, there are several phase I-II as well as preclinical phase studies evaluating vaccines for safety and immunogenicity, this include other live-attenuated platform/strategy, purified-inactivated viruses formulated with adjuvants, DNA vaccine, subunit vaccine, viral vector and also heterologous prime/boost strategies. The major difficulties of dengue vaccine development are included the lack of the best animal model, various immune status of individual especially in endemic areas and clear cut off of protective immunity. Several research and development efforts are ongoing to find a better effective and accessible dengue vaccine for people needed.