Immunogenicity and Safety of Japanese Encephalitis Vaccine When Given With Measles-Mumps-Rubella (MMR) Vaccine

This study aims to provide evidence that co-administration of measles-mumps-rubella vaccine (MMR) and live attenuated SA 14-14-2 Japanese encephalitis vaccine (CD-JEV) does not adversely affect immunogenicity or safety.

When incorporating a new vaccine in the Expanded Programme on Immunization (EPI), it is important to provide evidence that it can be introduced concurrently with other routine pediatric vaccines without significantly impairing the immune response to any vaccine while maximizing coverage and minimizing cost. This non-inferiority study aims to compare CD-JEV and MMR responses in a population of children in a country where MMR introduction is ongoing or planned. This information will help the ministries of health evaluate the addition of CD-JEV into routine EPI.

Eligibility Criteria:
Inclusion Criteria:

* Age 9 months to \< 10 months at the time of enrollment.
* Residence in the study area.
* At least one parent or guardian willing to provide written informed consent.
* Generally healthy and free of obvious health problems as established by medical history, physical examination, and clinical judgment.
* A parent or guardian is willing to attend all planned study visits and allow home visits and phone contacts, as required by the protocol.

Exclusion Criteria:

* Previous receipt of any measles-mumps-rubella containing vaccine.
* Previous receipt of any Japanese encephalitis vaccine.
* History of measles, mumps, rubella, or Japanese encephalitis infection.
* Administration of any other vaccine within 28 days prior to administration of a study vaccine or planned vaccination of any vaccine other than catch-up doses of routine EPI vaccines or oral polio vaccine during the 28 days after study vaccination.
* History of allergic disease or known hypersensitivity to any component of the study vaccines and/or following administration of vaccines included in the local program of immunization.
* Use of any investigational or non-registered drug within 90 days prior to the administration of study vaccines or planned administration during the study period.
* Administration of immunoglobulins and/or any blood products within 90 days prior to the administration of study vaccines or planned administration during the study period.
* Chronic administration (defined as \> 7 days) of immunosuppressing or other immune-modifying agents within 14 days before or after vaccination (including systemic corticosteroids equivalent to prednisone ≥ 0.5 mg/kg/day; topical and inhaled steroids are allowed).
* Primary or acquired immunodeficiency, including human immunodeficiency virus (HIV) infection, or a family history of congenital or hereditary immunodeficiency as reported by parent.
* Acute or chronic, clinically significant pulmonary, cardiovascular, hepatic, or renal functional abnormality, as determined by medical history or physical examination, which might interfere with the study objectives.
* Severely malnourished infants as measured by World Health Organization weight-for-height tables (Z-score \< -3).
* Any condition or criterion that, in the opinion of the study physician, might compromise the well-being of the participant, compliance with study procedures, or interpretation of the outcomes of the study.
* Acute illness at the time of enrollment defined as the presence of a moderate or severe illness with fever (axillary temperature ≥ 38.0°C) or without fever (severity determined at the discretion of the study physician). Acute illness is a temporary exclusion. Vaccination should be postponed at least 7 days after recovery. A visit for reassessment may be scheduled 7 days or more after temporary exclusion illness is resolved. Eligibility for study participation must be reassessed again at the next visit.