There are many vaccines that children must receive, mainly hepatitis B vaccine, BCG vaccine, polio vaccine, DPT vaccine and so on. The specific timing of the vaccinations necessary for the prevention of childhood infectious diseases in China is as follows: Within 24 hours of birth: Hepatitis B vaccine (first dose), BCG vaccine. One month of age: Hepatitis B vaccine (second dose). Two months of age: Polio (first dose). Three months old: Polio (second dose), DPT (first dose). April age: Polio (third dose), DPT (second dose). May age: DPT vaccine (third dose). June age: Hepatitis B vaccine (third dose), Group A Influenza vaccine (first dose). August age: MMR vaccine (first dose), Encephalitis B vaccine (first dose). September age: Group A Influenza Vaccine (second dose). Eighteen months old: DPT vaccine (fourth dose), MMR vaccine (second dose), Hepatitis A vaccine. Two years old: Encephalitis B vaccine (second dose), Hepatitis A vaccine (second dose). Three years old: Group A Group C Influenza vaccine (first dose). Four years old: Polio vaccine (fourth dose). Six years old: DPT vaccine, DPT vaccine (third dose), Group A Group C Strain Vaccine (second dose). The timing of vaccination may be related to the child’s physical (immunization) status and the presence of diseases, etc. The specific timing of vaccination or vaccination should strictly follow the instructions of medical professionals in order to avoid adverse consequences.