After more than a decade of development, the National Institute of Allergy and Infectious Diseases (NIAID) has started clinical trials to test a vaccine to protect against the dengue virus, a product researchers hope may one day “help prevent a disease to which 2.5 billion people are exposed,” CIDRAP News reports (Roos, 8/9).

Dengue is “caused by any of four related viruses –  DENV-1, DENV-2, DENV-3 and DENV-4,” which are “transmitted to humans by Aedes mosquitoes,” according to a NIAID press release. The disease is prevalent in the tropical and subtropical regions of the world. Of the estimated 50 million to 100 million people infected annually, it kills about 25,000, mostly children, according to NIAID. “The new vaccine is tetravalent, meaning that it is designed to protect against all four dengue viruses,” the release adds.

Three different mixtures of the vaccine will be tested on U.S. volunteers in a Phase I trial to “assess the safety and immunogenicity of the vaccine in healthy adults between the ages of 18 and 50, the agency said,” CIDRAP News continues (8/9). “After determining which tetravalent vaccine is most promising,” researchers will test that candidate in a trial on volunteers in Brazil, “where dengue has become highly prevalent,” the NIAID press release adds (8/9).

The announcement of the clinical trial “comes in the wake of recent dengue cases in Florida and unusually large epidemics of dengue fever in Latin America and the Caribbean. Florida officials last week reported a rash of dengue cases in state residents amid concern that the disease will gain a foothold in the state,” CIDRAP News reports (8/9).