>I'd never sign an informed consent form for medical testing.
Many military members chose to do so
Japanese encephalitis is a viral brain infection that's spread through mosquito bites. It's most common in rural areas in southeast Asia, the Pacific islands and the Far East, but is very rare in travellers. The virus is found in pigs and birds, and is passed to mosquitoes when they bite infected animals.
Fewer than 1 percent of people infected with the virus develop symptoms. However, according to the World Health Organization (WHO), it is fatal for 30 percent of those who do develop symptoms. Researchers estimate the number of fatalities from Japanese encephalitis is to be between 13,600 and 20,400 a year.
Japanese encephalitis vaccine is a vaccine that protects against Japanese encephalitis. The vaccines are more than 90% effective. The duration of protection with the vaccine is not clear but its effectiveness appears to decrease over time. Doses are given either by injection into a muscle or just under the skin. Wikipedia
Most people infected with JE do not have symptoms or have only mild symptoms. However, a small percentage of infected people develop inflammation of the brain (encephalitis), with symptoms including sudden onset of headache, high fever, disorientation, coma, tremors and convulsions. About 1 in 4 cases are fatal.