What is the composition and administration schedule of the Td (tetanus and diphtheria) vaccine?

Td Vaccine Composition and Administration

Vaccine Composition

Each 0.5 mL dose of Td vaccine contains 2-10 Lf units of tetanus toxoid and ≤2 Lf units of diphtheria toxoid (reduced dose compared to pediatric formulations). 1

• The reduced diphtheria content (≤2 Lf units) distinguishes Td from pediatric DT vaccine, which contains higher diphtheria toxoid concentrations that cause more frequent adverse reactions in persons ≥7 years of age 1
• Td formulations are adsorbed preparations administered intramuscularly, with a standard single-dose volume of 0.5 mL 1, 2
• The vaccine is specifically formulated for use in persons ≥7 years of age 1

Primary Immunization Schedule

For individuals ≥7 years who have never been vaccinated, administer a 3-dose primary series: first dose of Td, second dose 4-8 weeks (or 2 months) after the first, and third dose 6-12 months after the second. 1, 2

• The preferred approach is to substitute Tdap for one dose in the series (typically the first dose) to provide pertussis protection, followed by Td for the remaining doses 1
• Interrupting the schedule does not require restarting the series—simply continue from where the patient left off 1, 3

Booster Immunization Schedule

Routine booster doses are recommended every 10 years throughout adult life to maintain protection against tetanus and diphtheria. 1, 3, 4, 2

• For adolescents, the first booster should be Tdap at age 11-12 years, regardless of interval since last tetanus-containing vaccine 1, 3, 4
• After receiving Tdap, subsequent boosters every 10 years can be either Td or Tdap (updated 2019 ACIP guidelines allow flexibility) 3, 4
• Adults who have never received Tdap should receive one dose as soon as feasible, regardless of interval since last Td 1, 3

Wound Management Protocol

For contaminated or tetanus-prone wounds, administer a tetanus-containing vaccine if ≥5 years have elapsed since the last dose; for clean, minor wounds, the interval is ≥10 years. 1, 3, 5, 4

• Tdap is preferred over Td for persons ≥11 years who have not previously received Tdap 1, 5
• When both tetanus toxoid-containing vaccine and tetanus immune globulin (TIG) are indicated, administer each in separate syringes at different anatomic sites 1, 5
• Persons with unknown or incomplete vaccination history should be considered unvaccinated and may require both vaccine and TIG for contaminated wounds 1, 5

Special Populations

Pregnant women should receive one dose of Tdap during each pregnancy between 27-36 weeks gestation, regardless of prior vaccination history. 3, 4

• Healthcare personnel with direct patient contact should receive Tdap as soon as feasible, with intervals as short as 2 years after last Td acceptable 1, 6
• Adults ≥65 years should receive Tdap if they have never received it, with Boostrix preferred when feasible, though either product is acceptable 3

Critical Pitfalls to Avoid

• Do not administer tetanus boosters more frequently than every 10 years for routine immunization, as this increases risk of Arthus-type hypersensitivity reactions 3, 5
• Do not confuse the 10-year routine booster interval with the 5-year interval for contaminated wounds—this is the most common error in tetanus prophylaxis 5
• Do not use pediatric DTaP formulations in persons ≥7 years; use Td or Tdap instead 1, 3
• Persons with history of Arthus reaction should not receive tetanus toxoid-containing vaccine until >10 years after the most recent dose, even for wound management 1, 4