Approved vaccines schedules (series of vaccines given to an individual) cannot overload the immune system as these are carefully studied and calibrated for safe use. They offer a booster effect so that individuals are able to mount a stronger response should they get exposed to an infection. To reduce the number of shots as well as the number of visits children are offered combination vaccines. These are two or more vaccines combined into a single shot. Scientific data show that getting several vaccines at the same time (i.e multiple shots or combination vaccines) does not cause any chronic health problems. In fact, a number of studies have looked at the effects of giving various combinations of vaccines and when every new vaccine is licensed, it is tested along with the vaccines already recommended for a particular child’s age.