what is the purpose of booster shots?
So they need booster shots to build up immunity. Also, some people tend to lose their immunity over time if they don't receive the recommended booster shots. So booster doses are given to ensure that the immunity does build up even for those children in whom it didn't with the first vaccine. For some immunisations, your baby will need a course of vaccines to build up his defences and to provide life-long immunity.