Study of Live Attenuated Japanese Encephalitis Vaccine (ChimeriVax™-JE) and Yellow Fever Vaccine (STAMARIL®)

The purpose of this study is to obtain safety, tolerability, and immunogenicity data on the co-administration or sequential administration of Chimeravax™-JE vaccine and STAMARIL®.

Objectives:

Safety:

* Obtain safety and tolerability data of a single, fixed dose of ChimeriVax™-JE administered concurrently, one month before or one month after STAMARIL® to adult volunteers (≥ 18 to ≤ 55 years) without prior Japanese encephalitis (JE) or yellow fever (YF) vaccination.

Immunogenicity:

* Obtain data on the antibody response to a single, fixed dose of ChimeriVax™-JE administered concurrently, one month before or one month after STAMARIL® to adult volunteers without prior JE (or YF) vaccination.
* Assess the durability of the immune response in adult volunteers 6 months after administration of ChimeriVax™-JE and STAMARIL®.

All participants will receive two injections, one to each arm on Days 0 and 30, respectively. Immunogenicity will be tested on Days 0, 15, 30, 45, and 60, and at Month 6.

Eligibility Criteria:
Inclusion Criteria :

* All aspects of the protocol explained and written informed consent obtained from the participant.
* Aged ≥ 18 to ≤ 55 years at Day 0.
* In good general health, without significant medical history, physical examination findings, or clinically significant abnormal laboratory results.
* Participant must be available for the study duration, including all planned follow-up visits.
* The participant must agree to take the following precautions to avoid insect bites for 7 days following vaccination: (a) wear long-sleeved shirts and trousers; (b) apply N,N-Diethyl-meta-toluamide (DEET)-containing insect repellents; (c) sleep in screened enclosures.
* Female participants of childbearing potential must have a negative serum pregnancy test. An efficacious hormonal method (i.e., oral, implantable or injectable) of contraception or an intrauterine contraceptive device (IUCD) must be used at least 1 month before Screening and at least 1 month after Day 60. These participants will sign an agreement that contraception will be practised during the specified periods and will specify the method used. Female participants unable to become pregnant must have this documented (e.g., tubal ligation or hysterectomy).

Exclusion Criteria :

* A history of flavivirus infection or vaccination to Japanese encephalitis (JE) or yellow fever (YF). Previous vaccination will be determined by history (interview of subject) and/or by reviewing the participant's vaccination card or other official documentation (either a history of or documentation of vaccination fulfils the criterion for exclusion).
* Impaired immunity, including known or suspected immunodeficiency (e.g., human immunodeficiency virus \[HIV\] infection, primary immunodeficiency disorder, leukemia, lymphoma), use of immunosuppressive or antineoplastic drugs (including corticosteroids \> 10 mg prednisone, or equivalent, for more than 14 days in the last three months).
* Clinically significant abnormal laboratory assessment results.
* Serious adverse reactions characterised by urticaria or angioedema to a prior vaccine, chicken or eggs or egg protein.
* Transfusion of blood or treatment with any blood product, including intramuscular or intravenous serum globulin, within six months of the Screening Visit or up to Day 60.
* Administration of another vaccine within 28 days of receiving study vaccination.
* Physical examination indicating any clinically significant medical condition including any short-lived or long-standing illness which has become more severe.
* Body temperature \>38.1°C (100.6°F) or acute illness within 3 days prior to inoculation (participant may be rescheduled).
* Intention to travel out of the area prior to the study visit on Day 60.
* Seropositive to hepatitis C virus (HCV) or HIV or positive for hepatitis B virus (HBV) (antigen).
* Lactation or intended pregnancy in female participants.
* Excessive alcohol consumption, drug abuse, significant psychiatric illness.
* A known or suspected physiological or structural condition that compromises the integrity of the blood-brain barrier (e.g., significant hypertensive cerebrovascular disease, trauma, ischaemia, infection, inflammation of the brain).