Contraindications to vaccination include acute infectious disease or fever. Children with acute or chronic diseases such as kidney disease, heart disease or active tuberculosis, padded shoulders, susceptibility to convulsions, neurological sequelae of encephalitis, etc., and children with allergies should not be vaccinated. Other precautions are the adverse reactions after vaccination, which are very mild and manifest as redness, swelling and pressure pain at the vaccination site, and mostly subside on their own within 24 hours. A few babies may have a short-lived fever, which does not require special treatment, but if it exceeds 38℃, antipyretic measures are needed, and individual babies may have an allergic reaction, which should be consulted with the doctor.