Note these minimum acceptable ages and intervals may not correspond with the optimal recommended ages and intervals for vaccination.
*DTaP can be used in place of the fourth (and fifth) dose of DTP for children who are at least 15 months of age. Children who have received all four primary vaccination doses before their fourth birthday should receive a fifth dose of DTP (DT) or DTaP at 4-6 years of age before entering kindergarten or elementary school and at least 6 months after the fourth dose. The total number of doses of diphtheria and tetanus toxoids should not exceed six each before the seventh birthday.
**The booster dose of Hib vaccine which is recomnmended following the primary vaccination series should be administered no earlier than 12 months of age and at least 2 months after the previous dose of Hib vaccine.
#Although the age for measles vaccination may be as young as 6 months in outbreak areas where cases are occurring in children < 1 year of age, children initially vaccinated before the first birthday should be revaccinated at 12-15 months of age and an additional dose of vaccine should be administered at the time of school entry or according to local policy. Doses of MMR or other measles-containing vaccines should be separated by at least 1 month.