Tetanus Prophylaxis — ABEM Board MCQ

Correct answer: A — Tdap plus TIG

The correct answer is A, Tdap plus TIG. This patient has a wound that is neither clean nor minor and a vaccination history that is unknown, which is precisely the ACIP/CDC scenario requiring both active and passive immunization: Persons with wounds that are neither clean nor minor, and who have had fewer than 3 prior doses of tetanus toxoid or have an unknown history of prior doses, should receive TIG as well as tetanus toxoid vaccine. A single dose of toxoid alone is insufficient because early doses may prime the immune system without yet inducing protective immunity, so TIG is added to provide immediate passive antitoxin coverage while the vaccine stimulates active immunity. Because he is 19 and has no documented prior Tdap, Tdap is preferred over Td for this dose, since Tdap is preferred to Td for persons age 11 years or older who have not previously received Tdap. Giving both agents together, at separate injection sites, is standard practice for dirty, unknown-history wounds per current CDC wound management guidance. Why the other options are wrong: E. Tdap only: A single toxoid dose does not reliably raise antitoxin to protective levels quickly in an unprotected or unknown-status host, especially with a contaminated wound; TIG is required for that gap. C. Td only: This omits both the pertussis component indicated for an unvaccinated adult needing Tdap and the passive immunoglobulin needed for immediate protection against a contaminated wound. B. No prophylaxis: Unacceptable because unknown vaccination status with a dirty wound places the patient at real risk for tetanus toxin exposure; withholding treatment ignores established wound-risk stratification. D. TIG only: Immunoglobulin alone gives only temporary passive protection and does nothing to establish the patient's own long-term active immunity, so a toxoid-containing vaccine must also be given. Key point: Unknown or incomplete vaccination history plus a contaminated (not clean/minor) wound mandates both Tdap (active immunization) and TIG (immediate passive protection).

Reference: CDC/ACIP, Clinical Guidance for Wound Management to Prevent Tetanus (Pink Book, Chapter 21: Tetanus), 2024, https://www.cdc.gov/pinkbook/hcp/table-of-contents/chapter-21-tetanus.html