- History of Yellow Fever or out of study JE vaccination or known flavivirus infection since receiving ChimeriVax™-JE vaccination on Day 0 or Day 28 (during double-blind treatment period of the study). Yellow Fever/JE vaccination or flavivirus infection will be determined by history (interview of subject) and/or by reviewing the subject's medical records. Please note subjects who were flavivirus positive at Day 0 will be allowed to enrol on the study.