The first vaccine against dengue fever won clearance in Mexico, an initial step toward preventing the mosquito-borne infection that puts half of the world's population at risk. Sanofi expects more approvals in 'upcoming weeks' for the product, called Dengvaxia, in Latin America and Asia, Olivier Charmeil, who heads the Paris-based company's vaccines unit, said.The injection can thwart all four types of the virus, which has appeared in Portugal, France, Florida and Japan recently and increased the risk of 'explosive outbreaks,' according to the World Health Organization.Outbreaks are on the rise. Unlike malaria, another disease spread by mosquitoes, dengue affects wealthier urban populations in middle-income countries in Latin America and Asia in addition to poorer African nations.Dengvaxia, developed over the past 20 years at a cost of 1.5 billion euros ($1.65 billion), including manufacturing investments, awaits approval in at least 19 other countries. Mexico's regulator endorsed it for people between the ages of 9 and 45 living in areas where the disease is endemic.Dengvaxia's sales may reach $1.4 billion by 2020, according to analyst estimates compiled by Bloomberg. Sanofi said Dengvaxia "will be priced at a fair, affordable, equitable and sustainable price."Some countries may distribute it for free, said Guillaume Leroy, vice president of the dengue vaccine team at Sanofi. Dengue infection causes flu-like illness that can develop into potentially fatal complication.By Makiko Kitamura