The study was done in the United States, where dengue does not circulate in the population. This helped researchers identify the vaccine's effectiveness in people who had not been previously exposed to any strain of dengue.
In December, the dengue vaccine Dengvaxia was approved for use in Mexico, Brazil and the Philippines, following successful clinical trials started in 2011.
The vaccine proved effective against dengue symptoms in 56.5 percent of those studied and even more effective against the hemorrhagic fever, at 88.5 percent.
