The live attenuated vaccines currently in use include many types, mainly live attenuated vaccines for the prevention of measles, hepatitis A, chickenpox, encephalitis B, rubella, mumps, poliomyelitis, rabies and other diseases. Live attenuated vaccines currently in use include: live attenuated measles vaccine, live attenuated hepatitis A vaccine, lyophilized live attenuated hepatitis A vaccine, lyophilized live attenuated varicella vaccine, live attenuated encephalitis B vaccine, live attenuated rubella vaccine, live attenuated mumps vaccine, oral live attenuated polio vaccine, oral live attenuated rabies vaccine and so on. Live attenuated vaccines are a class of vaccines in which the pathogen is treated with formaldehyde to reduce toxicity, but the activity remains unchanged, maintaining both antigenicity. Vaccinate it into the body, and will not cause the occurrence of disease, but the pathogen can trigger the body’s immune response, stimulate the body to produce specific memory B cells and memory T cells. It plays a role in obtaining long-term or lifelong protection.