This study will evaluate the immunogenicity and safety of Beijing Tiantan's MMR vaccine in subjects 18 months of age and older. The MMR vaccine may be administered as a second dose to 4-6 year-old persons with one dose immunization with MMR vaccine or as a first dose to 18 month-old subjects with one dose immunization with measles-rubella(MR).

This study will evaluate the immunogenicity and safety of Beijing Tiantan's MMR vaccine in subjects 18 months of age and older.

The MMR vaccine may be administered as a second dose to 4-6 year-old persons with one dose immunization with MMR vaccine or as a first dose to 18 month-old subjects with one dose immunization with MR.

Immune efficacy and safety will be compared among different immunization schedules,including inoculation doses,enhanced immunity age,vaccination interval time.

Antibody persistence of 1 dose of MMR vaccine will be evaluated in this study.

Inclusion Criteria:

• healthy children; 150 subjects 18 months old; 150 subjects 4 years old;300 subjects 5 years old; 150 subjects 6 years old; their guardians signed informed consent;
• undiagnosed as measles, mumps and rubella;
• in good health as determined by the outcome of medical history, physical examination and clinical judgment; suitable to MMR immunization;
• guardians would comply with the requirements of the protocol;
• immunized with MR or measles vaccine(MV) at 8 months old;immunized with MMR at 18 months old(not applicable to subjects 18 months old); unvaccinated by biological products within one month;
• Axillary temperature ≤37℃;
• the local household population or permanent population;

Exclusion Criteria:

• history of allergic disease or reactions likely to be exacerbated by any component of the vaccine(any previous vaccination history of allergies and egg allergy history);
• Current confirmed as acute disease, severe chronic diseases or acute development of chronic diseases;
• Participating in another clinical trial at the same time;