It's worth to note this is one of a couple of promising vaccines, one of them is already approved in a couple of countries, as of December 2015: https://en.wiki

It's worth to note this is one of a couple of promising vaccines, one of them is already approved in a couple of countries, as of December 2015: https://en.wikipedia.org/wiki/Dengue_vaccine#CYD https://en.wikipedia.org/wiki/Dengue_vaccine#CYD . Not "100% efficient" but nothing really is, nor is that really needed, it's not a boolean thing but a continuum and having any kind of antibody response is better than none; it reduces the chances of more severe disease at least, if not prevent disease all-together.