Dear Colleague Letter - Clarification of the Tdap Vaccine Requirement

August 2008

Dear Colleague/School Personnel:

The New York State Department of Health (NYSDOH) has received several telephone calls from health care providers and school personnel requesting clarification of the recommendations and school requirements for Tdap vaccine. Clarification of vaccine requirements is important to avoid documentation and vaccine administration errors, administration of the wrong vaccine, or unnecessary school exclusion. The following summarizes the Department's recommendations and requirements for school entry.

DTaP is a pediatric formulation containing diphtheria and tetanus toxoids, and acellular pertussis vaccine. Tdap is an adolescent and adult formulation containing tetanus and diphtheria toxoids, and acellular pertussis vaccine. Tdap contains reduced amounts of diphtheria toxoid and acellular pertussis vaccine as compared with DTaP.

  • DT/DTaP should not be given after the 7th birthday.
  • The preferred age for Tdap vaccination is 11-12 years of age.
  • Tdap is licensed only for children ≥10 years (Boostrix®) or ≥11 years of age (Adacel®).
  • If a student has received a tetanus or diphtheria toxoid-containing vaccine within the preceding two years, the required Tdap vaccination can be deferred for a two-year period from the date of administration of that vaccine. However, if a student does receive Tdap within that two-year period, the dose is considered valid and the school requirement is satisfied.
  • If DTaP is given inadvertently (instead of Tdap), then Tdap does not need to be given. The school requirement is satisfied.
  • Any child without documentation of a primary series of at least three doses of a tetanus and diphtheria toxoid-containing vaccine should receive a series of three doses of such a vaccine. One of the doses, preferably the first, should be Tdap, if the child is at least 10 years of age. See the Centers for Disease Control and Prevention (CDC) link below for the immunization schedule.
  • Accurately documenting the administered vaccine as Tdap and not DTaP is crucial to avoid errors.
  • When the immunization record is obtained and it is unclear which vaccine was given, the health care provider must be contacted directly to verify Tdap was administered.

Additional information about Tdap can be found at CDC's website: The 2007-2008 New York State school requirements can be found at:

For more information on immunization school requirements, please contact your local health department or the NYSDOH Immunization Program at 518-474-1944.


Debra S. Blog, M.D., M.P.H.
Medical Director
Immunization Program


  • Local Health Department Commissioners
  • Public Health Directors