The other 2 arteries that bring blood to the brain, called the vertebral arteries, supply the brainstem. Plaque in the vertebral arteries is much less likely to break off and cause a stroke, but narrowing in the vertebral arteries can cause problems if the brainstem does not get enough blood flow.
A child should receive the first shot when he is between 12-15 months, and the second when he's between 4-6 years of age. If you're not sure if you have had the diseases or the vaccines (prior to 1971 it was given in three separate shots), you can get the MMR vaccine as an adult.
Vaccination can protect your child. In Canada, children get two doses of the MMR vaccine: 1  The first shot is given at 12 to 15 months of age. 2  The second shot is given at 18 months OR between ages 4 to 6 years (before your child starts school).