ACIP Issues Updated Recommendations for Use of Tdap Vaccine

The Journal of the American Medical Association [2011;305(9):878-880] presented a summary of a Morbidity and Mortality Weekly Report (MMWR) [2011;60:13-15] from the Centers for Disease Control and Prevention. The report outlined new recommendations from the Advisory Committee of Immunization Practices (ACIP) for pertussis vaccinations. Pertussis is not well controlled in the United States; there were 16,858 pertussis cases and 12 infant deaths reported in 2009.

To improve immunity against pertussis, ACIP recommendations issued in 2005 called for vaccination with tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) for adolescents and adults; however, Tdap coverage is 56% among adolescents and <6% among adults. ACIP issued updated recommendations in October 2010, calling for expanded use of Tdap. For adolescents aged 11 through 18 years who have completed the recommended childhood diphtheria and tetanus toxoids and pertussis/diphtheria and tetanus toxoids and acellular pertussis (DTP/DTaP) vaccination series and for adults aged 19 through 64 years, ACIP recommends a single Tdap dose.

There are 2 Tdap vaccines available in the United States: Boostrix (GlaxoSmithKline Biologicals, Rixensart, Belgium), licensed for persons aged 10 through 64 years, and Adacel (Sanofi Pasteur, Toronto, Canada), licensed for persons aged 11 through 64 years. Both products are licensed for use at an interval of at least 5 years between the tetanus and diphtheria toxoids. With the 2010 updates, ACIP approved additional recommendations: (1) use of Tdap regardless of interval since the last vaccine containing tetanus or diphtheria toxoids, (2) use of Tdap in some adults ≥65 years of age, and (3) use of Tdap in undervaccinated children ages 7 through 10 years.

The new recommendations were made following a review of published and unpublished Tdap immunogenicity and safety data from clinical trials and observational studies on use of Tdap. The review was conducted by the Pertussis Vaccines Working Group of ACIP. The group also considered the epidemiology of pertussis, provider and program feedback, and data on barriers to receipt of Tdap, and then presented options to the full ACIP for consideration. The options were designed to remove barriers and programmatic gaps that were contributing to incomplete vaccination coverage. One of the identified barriers was unknown history of Td booster; an important programmatic gap included lack of a Tdap vaccine license for children aged 7 through 10 years and persons ≥65 years of age.

The new recommendations are meant to ease the use of Tdap to reduce the burden of pertussis and the risk for transmission to infants. The recommendations for adults ≥65 years of age call for a single dose of Tdap to be administered to those who have or anticipate having close contact with an infant <12 months of age; other adults may also be given a single dose of Tdap. The new recommendations for children aged 7 through 12 years call for a single dose to be administered to children not fully vaccinated against pertussis when no contraindication to pertussis vaccine exists. ACIP defines fully vaccinated as 5 doses of DTaP or 4 doses of DTaP if the fourth dose was administered on or after the fourth birthday. In children aged 7 through 10 years where additional doses of tetanus and diphtheria toxoid are required, catch-up guidance should be followed, with Tdap preferred as the first dose. At present, Tdap is recommended only for a single dose across all age groups. There will be further guidance on time of revaccination in persons who have previously received Tdap from ACIP in the future, according to the MMWR.