We have lived in Efate for 9 years, and have never had dengue. True we are careful when we go outside and spray. All windows have insect screens. Even if you did get it, it's not a huge deal, there are much worse afflictions to be lumbered with. Yes, it's mainly in the wet season, but if you take care, make sure you are sprayed you should be fine. Please don't give up Vanuatu just for that.