Dengue is the most important mosquito borne virus infection in the tropics. Based on the effects of global warming, it is expected that dengue epidemic areas will further expand in the next decades unless effective and affordable vaccines are made available soon. At the moment, several vaccine developers have utilized live-attenuated live tetravalent vaccines and two of them have already completed phase two trials. However, the risk of antibody-dependent enhancement infection is not well elucidated and thus further and careful evaluation of the safety on proposed candidate vaccines are essential. At the moment, Bill and Melinda Gates Foundation strongly support the vaccine development through the Pediatric Dengue Vaccine Initiative.