>an attempt to control dengue fever
How the World’s First Dengue Vaccination Drive Ended in Disaster
Among Asian children two to five years old, those who had received the vaccine were seven times more likely than unvaccinated children to have been hospitalized for serious dengue in the third year after vaccination.
The same month, however, the highly respected advisory group on vaccines at the World Health Organization - which provides guidance to countries on immunization policy - stated in a briefing paper on Dengvaxia that the hospitalizations of young vaccinated children, when observed over several years, were not statistically significant. “No other safety signals have been identified in any age group” older than five, it stated. A “theoretical possibility” existed that the vaccine could be risky for some children
There the matter rested until November 2017, when Sanofi Pasteur issued its own advisory: those who had never experienced a dengue infection should not get Dengvaxia.
https://www.scientificamerican.com/article/how-the-worlds-first-dengue-vaccination-drive-ended-in-disaster/
Dengue vaccine fiasco leads to criminal charges for researcher in the Philippines
A first infection is rarely fatal, but a second one with a different virus type can lead to much more serious disease, because of what is called antibody-dependent enhancement (ADE), in which the immune response to the first virus amplifies the effect of the second type. Scott Halstead, a retired dengue expert formerly at the Uniformed Services University of the Health Sciences in Bethesda, Maryland, argued that dengue vaccines could have the same effect, and warned that Dengvaxia should not be given to children never infected with dengue. But a vaccine panel at the World Health Organization (WHO) concluded in 2016 that Dengvaxia was safe for children aged 9 and older.
https://www.science.org/content/article/dengue-vaccine-fiasco-leads-criminal-charges-researcher-philippines