All adults who did not receive the Tdap vaccination as a child should receive one dose of this vaccine. After they have had this dosage, they should have a Td or Tdap booster shot every ten years. Adults who have already received the Tdap vaccine do not need to receive it again. The Tdap vaccine is given intramuscularly into the arm or leg. The first dose is given at any time during the adult life cycle, with the second dose being given about six weeks after the first. Children require two doses of the Tdap vaccine; one dose is given at approximately 12-15 months and the second dose at 4-6 years. Adults who are not up to date on their vaccinations should see their doctor for an appointment so that they can be vaccinated.