Vaccines have proved hard to develop. Researchers have attempted to come up with a vaccine for 20 years with little success. The difficulty is that an effective vaccine would have to protect against all four dengue viral types. Should one part of the four ‘arms’ of the vaccine fail, those vaccinated would be at a greater risk for DHF than if those who had not been vaccinated at all.
 

Because of these hurdles, the NITD plans to concentrate its efforts on developing antiviral compounds. The idea is that administering antivirals in particular areas at the fist indication of an outbreak will be more cost-effective than mass inoculations.