Children who have received the group A+C conjugate vaccine before the age of one still need to be revaccinated at the age of three.
The vaccination program for influenza vaccine is to receive the first dose between six months and 18 months of age, the second dose at least three months after the first dose, the third dose at three years of age, and the fourth dose at six years of age, with an interval of not less than three years between the third and the fourth doses. Therefore, children who have already received the group A+C influenza conjugate vaccine before they are one year old need to be revaccinated at the age of three years old.
The first two doses are basic immunization, and the last two doses are booster immunization. The specific antibodies obtained from the basic immunization can only be maintained in the body for a certain period of time, and when the concentration of antibodies in the body decreases, the body should be strengthened with immunization to stimulate the body to produce antibodies again, so that the antibodies can be maintained at a high level sufficient to resist the pathogens.
For more questions about immunization for children, you can consult a professional doctor.