When to administer Td (tetanus and diphtheria) vs Tdap (tetanus, diphtheria, and pertussis) vaccine?

When to Administer Td vs Tdap

Tdap should be given once in a lifetime (with the exception of pregnancy), and Td should be used for all subsequent tetanus-diphtheria boosters every 10 years thereafter. 1

Primary Decision Algorithm

For Adults ≥18 Years

• If the patient has never received Tdap: Administer Tdap now, regardless of interval since last tetanus-containing vaccine 1
• If the patient has previously received Tdap: Use Td for routine 10-year boosters 1
• Exception - Pregnancy: Administer Tdap during each pregnancy between 27-36 weeks gestation, regardless of prior Tdap history 1, 2

For Adolescents and Children (7-18 Years)

• Ages 11-12 years: Give one dose of Tdap as the adolescent booster 1
• Catch-up vaccination (ages 7-18): Give Tdap as the first dose, then use Td for any additional needed doses 1
• If Tdap given at ages 7-10: Still give another Tdap dose at ages 11-12 years 1

For Wound Management

• If patient has never received Tdap or Tdap history unknown: Use Tdap (preferred over Td) when tetanus vaccine is indicated 1
• If patient has documented prior Tdap: Use Td when tetanus vaccine is indicated 1
• Timing: Tetanus-containing vaccine indicated if >5 years since last dose for contaminated/tetanus-prone wounds, or >10 years for clean minor wounds 1, 3
• Pregnant women requiring wound prophylaxis: Use Tdap 1

Key Clinical Principles

The "One Tdap Rule"

Tdap is licensed and recommended as a single-dose vaccine for the general population (except pregnancy), not for repeated administration 1. After receiving Tdap, all subsequent routine boosters should be Td every 10 years 1, 3.

No Minimum Interval Required

When Tdap is indicated, administer it regardless of interval since the last tetanus or diphtheria-containing vaccine. 1 The ACIP concluded that protection against pertussis outweighs the potential risk of increased local reactions from shorter intervals 1.

Special Populations

• Adults ≥65 years: Give Tdap if never received, preferably using Boostrix (though either product is acceptable) 1, 3
• Healthcare personnel and those with infant contact: Prioritize Tdap administration; can give as soon as 2 years after last tetanus vaccine 4
• Pregnant women: Tdap during each pregnancy at 27-36 weeks (preferably early in this window), regardless of prior Tdap history 1, 2
• Unvaccinated adults: Give 3-dose series with one dose being Tdap (preferred as first dose), followed by Td at ≥4 weeks, then Td at 6-12 months 1

Critical Pitfalls to Avoid

• Do not give tetanus boosters more frequently than every 10 years for routine immunization - this can cause Arthus reactions (severe local hypersensitivity) 3
• Do not use DTaP in persons ≥7 years - use Tdap or Td instead 1
• Do not miss opportunities to give Tdap to adults who have never received it - administer regardless of when they last received Td 3
• Do not restart the vaccination series if doses are delayed - simply continue from where the patient left off 1, 3
• Do not withhold Tdap due to short interval since last Td - when indicated, give Tdap regardless of interval 1

Practical Summary Table

Clinical Scenario	Vaccine Choice	Key Citation
Never received Tdap	Tdap now	[1]
Prior Tdap documented	Td for boosters	[1]
Pregnancy (any)	Tdap at 27-36 weeks	[1,2]
Wound + no prior Tdap	Tdap preferred	[1]
Wound + prior Tdap	Td	[1]
Age 11-12 years	Tdap	[1]