Vaccines work best when they are given at certain ages. For example, the measles vaccine is not usually given until a child is at least a year old. If it is given earlier than that, it may not work as well. On the other hand, DTaP vaccine should be given over a period of time, in a series of properly spaced doses.
This chart shows the routine childhood-immunization schedule. It tells what childhood vaccines are recommended, and the ages at which they should be given.
Read across the chart to see how many doses of each vaccine are recommended, and when. Read down the chart to see which vaccines are given at specific ages. A circle means the vaccine should be given at that age. A bar means it may be given at any point over a period of time.
SOURCE: Based on the immunization schedule recommended by the Centers for Disease Control and Prevention, the American Academy of Pediatrics, and the American Academy of Family Physicians, 2002
Vol. 23, Issue 43, Page 28