FA16 Immunization Module’s Updates

Timing of Vaccinations & Adverse Reactions: DTaP vs. Tdap

Multiple formulations of combination vaccines exist for tetanus, diphtheria, and pertussis. The Td vaccine immunizes against the tetanus and diphtheria toxoids, while DTaP and Tdap also include protection against pertussis. Despite the upfront similarities between the DTaP and Tdap vaccines, differences exist that are important to keep in mind when choosing a formulation.

The primary difference is in the antigenic dosages used in each formulation. DTaP vaccines have a comparatively higher amount of diphtheria toxoid and acellular pertussis antigen. These antigens are reduced in dose per Tdap vaccine.1,3 “D” and “P” are capitalized in DTaP to signify the higher levels of respective antigen present.1

This difference in antigenic dosage also affords differences in protective immunity and adverse effects. Thus, DTaP and Tdap are indicated for use in different populations. DTaP should be used to vaccinate children under 7 years of age because the higher antigen levels present are necessary to mount an adequate initial immune response. Tdap should be used as a booster immunization for children older than 11 years of age and adults, when a reduced antigen dosage is sufficient.1,3 The reduced antigen level also means that the incidence of adverse effects is decreased with Tdap than DTaP, although the type and severity of adverse effects are similar between the two and are mostly localized reactions.1,2,3 Patients who receive DTaP instead of Tdap as a booster do not need to be revaccinated with Tdap, but should be informed of the increased risk of developing side effects. However, a child improperly vaccinated with Tdap instead of DTaP should be revaccinated with DTaP.1,3

Confusion between DTaP and Tdap continues to occur during vaccine administration. Recognition of the differences, in addition to improved labeling and oversight of dosages, should help minimize incorrectly administered vaccines.3

1DeDea, L. The difference between Tdap and DTaP; dabigatran versus warfarin. (2011) Journal of the American Academy of Physician Assistants. 24(1):14.

2Klar, S; Harris, T; Wong, K; Fediurek, J; Deeks, SL. Vaccine safety implications of Ontario, Canada’s switch from DTaP-IPV to Tdap-IPV for the pre-school booster. (2014) Vaccine. 32(48):6360-3.

3Paparella, S. Alphabet soup: confusion between DTaP and Tdap. (2010) Journal of Emergency Nursing. 36(6):570-1.

DeDea 2011
Klar et al 2014
Paparella 2010

 

  • Matthew Law
  • Richard Tapping
  • Troy Watson
  • Mary Clark