Preteen and Teen Immunizations
Inactivated poliovirus vaccine (IPV)
For children who received an all-IPV or all-oral poliovirus (OPV) series, a fourth dose is not necessary if the third dose was administered prior to the age of 4. If both OPV and IPV were used as part of a series, a total of four doses should be administered, regardless of the child's current age.
There has been no polio in the Western Hemisphere since 1987 but, again, easy international travel can increase the risk of transmission.
Measles, mumps and rubella vaccine (MMR)
For any young person found to have not been previously vaccinated, two doses of MMR should be given at any age, with at least four weeks between the doses.
Varicella (chickenpox) vaccine
Any child less than 13 years of age not previously vaccinated -- or showing no evidence of prior immunity -- should receive two doses of varicella vaccine at least three months apart. For young people older than 13, the two doses should be at least four weeks apart.
You can download your own schedule of recommended preteen and teen immunizations from the CDC web site.