In an adult, which is better, Td (tetanus and diphtheria) vaccine or TT (tetanus toxoid) vaccine?

Td vs TT for Adult Vaccination

Adults should receive Td (tetanus-diphtheria) vaccine rather than TT (tetanus toxoid alone), and ideally should receive Tdap (tetanus-diphtheria-acellular pertussis) at least once to replace a single Td dose. TT monovalent vaccine is no longer recommended for routine adult immunization because it fails to provide protection against diphtheria, which remains a public health concern. 1, 2

Primary Recommendation

• The Advisory Committee on Immunization Practices (ACIP) recommends that all adults aged ≥19 years should receive Td or Tdap for tetanus prophylaxis, not TT alone. 1, 2
• Adults who have never received Tdap should get one dose of Tdap regardless of when they last received a tetanus-containing vaccine, followed by Td boosters every 10 years. 2, 3

Why Td Over TT

• Td provides dual protection against both tetanus and diphtheria with a single injection, whereas TT only protects against tetanus. 2, 4
• Serosurveys indicate that 49%-66% of adults ≥60 years lack protective levels of circulating antitoxin against diphtheria, making the diphtheria component essential. 2
• After receipt of Td, subsequent doses of tetanus- and diphtheria toxoid-containing vaccines should follow guidance from previously published recommendations for the use of Td (not TT). 1

Why Tdap Is Even Better Than Td

• Tdap should replace one Td booster dose in all adults aged ≥19 years who have not previously received Tdap, providing additional protection against pertussis. 1, 3
• Immunity to pertussis wanes approximately 5-10 years after childhood vaccination, leaving adults susceptible and capable of transmitting pertussis to vulnerable infants. 3
• After receiving one dose of Tdap, adults should continue with Td boosters every 10 years. 2, 3

Clinical Algorithm for Adult Tetanus Vaccination

For routine immunization:

• If the patient has never received Tdap → Give Tdap now (regardless of interval since last Td). 2, 3
• If the patient has previously received Tdap → Give Td for routine 10-year boosters. 2, 3

For wound management:

• Clean, minor wounds: No vaccine needed if last dose <10 years ago; give Tdap (if never received) or Td if last dose ≥10 years ago. 2, 4
• Contaminated/severe wounds: Give Tdap (if never received) or Td if last dose ≥5 years ago, plus TIG 250 units IM if primary series incomplete. 2, 4

For adults with uncertain vaccination history:

• Treat as unvaccinated and give complete 3-dose primary series: Tdap immediately, then Td at least 4 weeks later, then Td 6-12 months after the second dose. 2, 4

Special Populations Requiring Tdap Priority

• Healthcare workers with direct patient contact should receive Tdap as soon as feasible, with intervals as short as 2 years from last Td acceptable. 1, 3
• Adults with close contact to infants <12 months (parents, grandparents, childcare providers) should receive Tdap at intervals <10 years since last Td, ideally at least 2 weeks before contact begins. 1, 3
• Pregnant women should receive one dose of Tdap during EACH pregnancy at 27-36 weeks gestation, regardless of prior Tdap history. 2, 4

Important Caveats

• Do not give tetanus boosters more frequently than every 10 years for routine immunization to avoid Arthus reactions (severe local hypersensitivity reactions with pain, swelling, and induration developing 4-12 hours post-injection). 2
• For wound management in contaminated injuries, the 5-year rule applies (not the 10-year rule for routine boosters). 2, 4
• TT monovalent vaccine may still be used in specific circumstances such as tetanus-prone wound management when Td or Tdap are unavailable, but this is not the preferred approach. 1

Immunogenicity Evidence

• Td vaccine produces protective serum tetanus antitoxin levels (≥0.1 IU/mL) in >96% of adults and protective diphtheria antitoxin levels (≥0.1 IU/mL) in 71% of adults ≥60 years. 5
• Complete primary tetanus vaccination provides long-lasting protection of ≥10 years for most recipients, with antibody half-life estimated at 14 years for tetanus and 27 years for diphtheria. 2, 6
• Tdap produces seroprotective antibody levels against all three antigens (tetanus, diphtheria, pertussis) in >90% of recipients across all age groups. 7, 8