Determining Long-Term Safety and Efficacy of Japanese Encephalitis Vaccine When Given With Measles Vaccine

• Seroconversion rates at 36 months post-vaccination for the measles antibody response in infants aged 8-11 months at time of vaccination [ Time Frame: 36 months post vaccination ] [ Designated as safety issue: No ]
  

• Seroconversion rates at 12 and 24 months post-vaccination for the measles antibody response; [ Time Frame: 12 and 24 months post vaccination ] [ Designated as safety issue: No ]
  
• Seroconversion rates at 12, 24, and 36 months post-vaccination for JE; Evaluation of the long-term (12, 24, and 36 months post-vaccination) safety profiles of the concurrent administration of JE live attenuated SA 14-14-2 and measles vaccine. [ Time Frame: 12, 24, and 26 months post vaccination ] [ Designated as safety issue: Yes ]
  

Japanese encephalitis is the leading cause of viral neurological disease and disability in Asia. The severity of sequelae, together with the volume of cases, make JE the most important cause of viral encephalitis in the world. Approximately 3 billion people—including 700 million children—live in Asian areas at risk for JE. JE most commonly infects children between the ages of 1 and 15 years, and can also infect adults in areas where the virus is newly introduced. More than 50,000 cases are reported annually and cause an estimated 10,000 to 15,000 deaths. This figure is believed to represent only a small proportion of the disease burden that actually exists.

An effective vaccine has existed since 1941, but has not reached the poorest countries in Asia. During the 60 years that the vaccine has been available, JE has infected an estimated 10.5 million children, resulting in more than 3 million deaths and more than 4 million children living with long-term disabilities. Control of this disease has been limited due to poor disease surveillance, a limited and unstable vaccine supply, lack of guidance and programmatic support for immunization, and limited advocacy.

A successful vaccine should be safe, efficacious, affordable, administered in a single dose, and easily incorporated into the routine Expanded Programmes on Immunization (EPI) programs.

This trial is designed to determine the potential interference between the measles vaccine and the Japanese encephalitis vaccine at 12, 24, and 36 months post-vaccination. As these vaccines will be used in routine EPI systems at the same time, similar to how measles and yellow fever vaccine (also a Flavivirus) are administered, it is imperative to collect long-term data showing that neither vaccine interferes with seroconversion of the other when co-administered.This information will help to ensure subject safety and facilitate programmatic efficiency, reducing the number of immunization visits for both parents and health care workers.