Clinical Trial of Measles, Mumps and Rubella Combined Vaccine, Live

Inclusion Criteria: Provide vaccination certificate and birth certificate for healthy children aged 8-12 months; * Volunteers' legal guardian informed consent, volunteered to participate and signed an informed consent form； * The volunteer's legal guardian has the ability to understand the research procedures, use the thermometer, scale and fill in the diary card as required, and can complete the clinical study in accordance with the requirements of the clinical trial protocol. Exclusion Criteria: * The axillary body temperature on the day of enrollment was more than 37.0 ℃; * Have suffered from measles, mumps and rubella in the past or are suffering from measles, mumps and rubella; * Any previous vaccination containing measles, mumps and rubella; * Persons known to be allergic to any ingredient in the investigational vaccine; * Any previous history of vaccine or drug allergy; * Premature (delivered before the 37th week of pregnancy) and low weight (birth weight \< 2500g); * History of dystocia, asphyxia rescue and nervous system damage; * Congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc; * Acute disease, serious chronic disease or acute attack of chronic disease on the day of vaccination; * Have a history of live attenuated vaccine within 28 days before vaccination and other vaccines within 7 days; * Those who receive immune enhancement or inhibitor treatment within 3 months (continuous oral or drip for more than 14 days); * …