The MMR vaccine is currently mandated for children in China. The MMR vaccine is mainly used to prevent measles, rubella and mumps. The above three diseases are acute respiratory infections caused by measles virus, mumps virus and rubella virus, with the following symptoms: 1. Measles: Typical symptoms of measles are high fever, cough, measles mucous membrane spots and rash. 2. Rubella: Typical symptoms of rubella are fever, rash, swollen lymph nodes behind the ear and occipital area. 3. Mumps: Mumps is a non-suppurative swelling of the parotid gland, centered on the earlobe and spreading forward, backward and downward. The swelling is centered on the earlobe and spreads forward, backward and downward, first on one side and then on the other. Measles, rubella and mumps can develop all year round, but they all have a high incidence in the spring and can be transmitted through the respiratory tract.