• A highly effective vaccine exists and is currently in use against yellow fever. The vaccine utilizes the live, attenuated 17D strain which was developed in the 1940s by Max Theiler. Today the vaccine is freeze-dried for use in the tropics. Vaccination produces mild side effects in only 5% of vaccinees and yields life-long immunity in 95% of recipients. For travel an updated certificate of vaccination is required every 10 years. In South America and Africa, the vaccine is slowly being integrated into the normal childhood vaccination schedule. Vaccination policy is not uniform in all endemic areas though.
  • An experimental live, attenuated, subcutaneous, tetravalent dengue vaccine containing the 16681-PDK 53 (DEN 2) strain has been in clinical trials since 1987. The vaccine has been tested in mice but has not been proven safe and effective in humans.
  • Formalin inactivated, mouse brain-derived vaccine is currently used to prevent Japanese encephalitis in pigs, horses, and Japanese children and a cell grown inactivated vaccine is used in China. These inactivated vaccines remain unlicensed in the United States. Recently, the BIKEN live attenuated vaccine was licensed in Japan.
  • Formalin inactivated vaccine is also available for the prevention of tick-borne encephalitis.