SINGAPORE (AP) — French drug maker Sanofi-Aventis SA plans to widen Asian clinical trials of a potential first-ever dengue fever vaccine. The drug company's vaccine division, Sanofi Pasteur, said it will test the vaccine in Singapore and Vietnam, adding to ongoing studies in Thailand and the Philippines. The company said it may seek regulatory approval of the vaccine as early as 2015. The Asian trials are part of a second phase of studies that includes tests on children and adolescents in Peru and Mexico, Melanie Saville, head of Sanofi's dengue program, said in a statement. A third and final phase would involve large-scale trials and production of the drug, Saville said. Dengue fever is a disease transmitted by mosquitoes, infecting 230 million people annually. Symptoms include high fever, bleeding, severe headache, and mild fever. Dengue hemorrhagic fever, which affects 2 million people annually, can lead to death.