DTaP produces fewer side effects and is a safer version of an older vaccine called DTP, which is no longer used in the United States. Tdap vaccine is licensed for people 10 years through 64 years of age. Tdap contains a lower concentration of diphtheria and pertussis toxoids than DTaP. Tdap is given at 11-12 years.Adolescents and adults who have not yet received it should get a one time dose of Tdap at the time of their next tetanus booster.TaP / Tdap / DTP / Td Are you confused about what vaccine you or your child needs? Diphtheria, tetanus, and pertussis are all diseases caused by bacteria. All three can cause severe illness and death. Diphtheria and pertussis are spread from person to person.