Can The Immune System Handle It?
Beyond just the number of pokes children are subjected to, some parents are even more concerned that the multitude of vaccines given to young children will overwhelm their immune systems. After all, it was not all that long ago when there was only one recommended vaccine (smallpox). In contrast, parents today are expected to give their children a whole slew of shots (with eleven currently recommended vaccines).
At the same time, far more is known about the immune system and how it works today than in generations past. Not only do we know that an infant's immune system is functional and able to respond well to vaccines, but we also have vaccines that are much more "targeted" than in days past. While the number of recommended childhood vaccines has continued to increase, the number of components in each vaccine that trigger an immune response (called antigens) is actually less than the number found in the single small pox vaccine of the last century.