Dengue fever is a life threatening mosquito borne virus and is on the rise. Spread by the same mosquito that carries the Zika virus, half the world’s population is now at risk. Around 400,000 people are hospitalised each year and thousands - mostly children - die. Worse still, there is no treatment for dengue fever. Filmed in the Philippines, USA, Mexico and Brazil, this documentary charts the seventy year search for an effective vaccine against the complex disease. The very first vaccine is now becoming available, the first step towards curbing the increasing threat.