A study of the study vaccine (JECEVAX- VABIOTECH-Vietnam) and a licensed vaccine (JEVAX-VABIOTECH-Vietnam) is conducted in Vietnamese children, aged 9 to 24 months to assess the safety of the study vaccine compares to licenced vaccine. Two hundred and twenty children are enrolled and randomly assigned into 2 groups (110 children/group), each of which receive 2 doses of study / control vaccine subcutaneously, at 28-34 days interval. Safety data included immediate reaction at the injection site and systemic reaction within 30 min of administration, solicited and unsolicited adverse events occurs from the 1st dose to 28-34 days after first dose and from the second dose to 28-34 days after 2nd dose. SAE (from start of first dose to 28-34 days after second dose).