Children are usually vaccinated with the third dose of hepatitis B vaccine at 6 months of age, and the third dose of the new coronary vaccine is given at intervals greater than 4 weeks from the second dose. Different vaccines are given at different times. If the child is vaccinated with hepatitis B vaccine, the 3rd shot is given at 6 months of age; the 1st shot of hepatitis B vaccine is given on the day of birth, and the 2nd shot is given when the child reaches one month of age, and the 3rd shot is given when the child reaches 6 months of age; the hepatitis B vaccine is used for the prevention of hepatitis B. The 3rd shot is given at an interval of more than 4 weeks from the 2nd shot. In the case of the New Crown vaccine, it is important to note that the vaccine can only be given at the age of three years or older, and that a booster shot is not required between the ages of 3 and 17 years. Unlike the hepatitis B vaccine, the 3rd dose of the recombinant subunit New Crown vaccine should be given greater than 4 weeks from the 2nd dose, and the 3rd dose should be completed as close as possible to 6 months after the 1st dose. Vaccination can produce adverse reactions such as fever, headache, nausea and vomiting, itchy skin, rash, etc. People with allergies should be cautious about vaccination. Children who receive the 3rd vaccination should actively seek medical attention if adverse results occur.