To understand how vaccines work, first we have to look at how immunity works. Immunity The job of our immune system is to protect us from things that enter our body that don’t belong there. This includes disease germs like viruses or bacteria. The immune system recognizes these intruders as “non-self,” and produces proteins called antibodies to get rid of them. But your immune system does more than find and destroy these germs. It also remembers them, so if the same germs ever enter your body again, antibodies will be quickly dispatched to destroy them before they can make you sick. This is why someone who catches a disease like measles or chickenpox can be exposed to the disease many times afterward without ever catching it again. This is immunity. This is a very efficient system, but there is one problem with it. The first time a child is exposed to a disease, the immune system can’t create antibodies quickly enough to keep him from getting sick. Eventually the immune system will fight off the infection, and leave the child immune from future infections from the same disease. But it doesn’t prevent the disease the first time. In other words, a child has to get sick before becoming immune.
Click on the CDC link to the left to find out information about Measles and other Important Vaccine information