The Tdap vaccine is given to protect against tetanus, diphtheria, and pertussis (whooping cough). Here is how often it is recommended:

• Children under 7 years old receive the DTaP vaccine series of 5 doses at 2 months, 4 months, 6 months, 15–18 months, and 4–6 years of age

• Adolescents should receive a single dose of Tdap at 11 to 12 years of age. If missed, it should be given at the next opportunity

• Adults who have never received Tdap should get a single dose as soon as feasible. After that, a booster dose of either Td or Tdap is recommended every 10 years to maintain immunity

• Pregnant women are recommended to get a dose of Tdap during each pregnancy, preferably between the 27th and 36th week, to protect the newborn from pertussis

In summary, after the initial Tdap dose (usually at 11-12 years or first adult dose), booster shots are recommended every 10 years with either Tdap or Td vaccine. Pregnant women should receive Tdap during every pregnancy regardless of previous vaccination history