What is the right age for the second booster?

Q: My brother is 4.2 years old. I would like to know as to what is the appropriate age for being given the DPT booster second dose. Some doctors say that 5 years is the right age, whereas the others say it is 4 years. If the right age is 5 years, then should he be given the vaccine as soon as he turns 5 years old? What will happen if he is vaccinated at the age of 4.5 years?

A:The recommended age for the second booster is on completion of five years of age if the first booster has been given on completion of one and a half years of age. No adverse effects will happen if you give it at four and a half years of age, but the efficacy is likely to be lower.