Long-term Immunogenicity After Receipt of JE Vaccine and Antibody Response and Safety to a Booster Dose

Assessment of Long Term Immunogenicity of Japanese Encephalitis Live Attenuated SA-14-14-2 Vaccine in Previously Vaccinated Bangladeshi Children and Antibody Response and Safety to a Booster Dose

This study aims to understand the persistence of the Japanese encephalitis (JE) antibody response in previously vaccinated children. The proposed study will enrol Bangladeshi children who had previously participated in a lot to lot consistency study (JEV05; NCT01567865) of JE live attenuated SA 14-14-2 vaccine (CD-JEV).

Study participants previously immunized with CD-JEV (Clinical Trials identifier: NCT01567865, JEV05) will have serum collected three and four years after initial vaccination to assess long-term immunogenicity. Four years after receiving the initial dose of CD-JEV, eligible participants will be vaccinated with a second subcutaneous dose of CD-JEV to assess the antibody response.

Participants will be monitored for safety for 28 days following receipt of the booster dose.

Inclusion Criteria:

• Participant in JEV05 study (NCT01567865) and received one dose of CD-JEV.
• Resides in the Matlab or Mirpur study area.
• At least one parent or guardian willing to provide written informed consent.

Exclusion Criteria:

• Received a second dose of Japanese encephalitis vaccine within the past three years.
• Received immunoglobulins and/or any blood products within 90 days prior to enrollment.
• Been diagnosed with a primary or acquired immunodeficiency, including human immunodeficiency virus (HIV) infection within the past three years.