The Centers for Disease Control and Prevention recommends that children receive their first dose of the Diphtheria, Tetanus and Pertussis vaccine when they are two months old. Children with minor illnesses must recover before they can receive the vaccine.
Children can receive further doses of the DTaP vaccine at the ages of four months, 6 months and 15 to 18 months. The CDC notes that children can get the last dose between the ages of 4 and 6.
If a child has an allergic reaction after a DTaP dose or has a brain or nervous system disease within seven days of receiving a dose, he should not get further doses, states the CDC.