Japanese encephalitis (JE) is a mosquito-borne viral infection that poses serious health risks, including permanent brain damage and death. While 99% of infected individuals do not develop symptoms, those who do face severe consequences, with a fatality rate of up to 30%. Survivors often experience long-term disabilities, such as cognitive impairment, paralysis, seizures, or memory loss. Despite being more commonly associated with children, adults are not immune to the risks of JE, particularly in endemic regions like the Philippines.

Vaccination is one of the most effective tools against JE. Countries that have implemented widespread JE vaccination programs, such as Japan, China, and South Korea, have seen dramatic reductions in incidence rates. However, in the Philippines, where JE contributes to 16–40% of clinical encephalitis cases, vaccination rates remain low, leaving many adults vulnerable.

The Japanese encephalitis vaccine is approved for use in both children (aged 2 months and older) and adults. For adults, vaccination provides critical protection, especially for those living in or traveling to high-risk areas.