<qa>  What is the leading cause of illness and death in the tropics and subtropics?Dengue infection is a leading cause of illness and death in the tropics and subtropics. The infection is caused by any one of four types of the dengue virus. This study will evaluate the safety of and immunogenicity to a vaccine called TV003 against all four types of the dengue virus in healthy adults, adolescents, and children aged 12 months to 50 years in Thailand. 