I'm not sure I understand. The usual vaccine schedule has a gap from about 18-24 months until kindergarten at age 4 or 5. Other than yearly flu vaccines, nothing is usually given in that gap. So most 2 year olds aren't due for any vaccines until kindergarten. That's not accidentally, that's what's supposed to happen to protect kids safely and effectively.
Were some vaccines given earlier than they were supposed to have been given? Which ones?