Dengue infects an estimated 400 million people worldwide each year. The virus spreads to human beings through the bite of an insect, the mosquito. Most people who get dengue suffer health problems like those resulting from a mild case of influenza, like a higher than normal body temperature. But the illness is more severe the second time a person gets it. In serious cases, it can cause bleeding inside the body and even death. About 25,000 people a year die from the infection. The drug Dengvaxia is so far the only vaccine approved for use against dengue. Several countries - including Brazil, Mexico, Costa Rica, Paraguay and the Philippines - have already approved use of the drug. But health officials are still trying to decide the best way to release the vaccine. Trials of Dengvaxia involved more than 30,000 people in 10 countries. Among young people, the drug was found to reduce infections by 60 percent, and hospitalizations by 80 percent. But over time, many of those vaccinated got seriously ill with dengue.
