Please go through the Immunization schedule
DTP first booster is required at 16-24 months of age, followed by a second booster at 4-6 yrs of age. Tdap vaccine is required at 11-12 years of age to provide immunity to school going children. Boosters serve as a reminder to our immune system to fight against diseases and are equally important as the primary doses given to a newborn.
Vaccine schedules are designed after rigorous research to provide maximum benefits in terms of immunity to children. They should be followed strictly to gain complete immunity.