If used improperly, the vaccine for dengue could actually worsen the disease and lead to serious infections. There is currently only one approved vaccine, which has been licensed in six countries. Dengue has been found in Puerto Rico, Latin America, Southeast Asia, and the Pacific Islands.
Dengue is spread by mosquitoes and can lead to a mild infection. The concern is, if the vaccine fails to fully protect, then there is a risk of making the person sick.
The researchers analyzed data from dengue vaccine trials involving over 30,000 people in 10 countries. The study found that although the dengue vaccine reduced illness and hospitalizations by up to 30 percent in areas of high transmission, it could also increase the risk of serious illness in areas with low transmission.
“We should be careful in considering where and how to use this vaccine as there is still uncertainty about its impact,” concluded coauthor Derek Cummings.