The hunt is on for A Vaccine for Dengue. Dengue fever affects up to 100 million people every year, mainly children.
It kills about 20,000 – and they die from what is known as dengue shock syndrome.
Sanofi Pasteur and GSK, two of the biggest drug companies in the world, have been working on a dengue fever vaccine for some time.
We go to Thailand and Vietnam to see what progress is being made.
This film is one of 57 x 25-minute documentaries produced for the BBC in the multiple series KILL OR CURE. These films can be bought individually or as a series.