Inviragen Inc., of Fort Collins, Colo., started a Phase II randomized, double-blind, placebo-controlled study of DENVax, an investigational dengue vaccine based on an attenuated DEN-2 virus. The trial will test the safety and immunogenicity of DENVax in multiple age groups in dengue-endemic countries. Data from a Phase I study demonstrated the vaccine is safe and well tolerated and immunogenic in dengue-naive adults.