From the Guidelines
You can get a Tdap vaccine as soon as it is indicated, regardless of the interval since the last tetanus or diphtheria toxoid–containing vaccine, according to the latest recommendations from the Advisory Committee on Immunization Practices (ACIP) in 2019 1.
Key Considerations
- The ACIP recommends that a dose of Tdap, when indicated, should not be delayed and should be administered regardless of the interval since the last tetanus or diphtheria toxoid–containing vaccine 1.
- If a tetanus toxoid–containing vaccine is indicated for wound management, Tdap is recommended for pregnant women, and Td is recommended for nonpregnant persons aged ≥7 years who had previously received Tdap 1.
- Pregnant women should receive a dose of Tdap during each pregnancy to prevent pertussis in infants too young for routine vaccination 1.
Exceptions and Special Cases
- For previously unvaccinated persons aged ≥7 years, a 3-dose catch-up immunization schedule includes only 1 dose of Tdap, preferably as the first dose in the series, and 2 subsequent Td doses at specified intervals 1.
- Children aged 7–10 years who received Tdap as part of the catch-up schedule are recommended to receive the routine adolescent Tdap booster dose at age 11–12 years 1.
Important Notes
- The FDA approved Adacel for a second Tdap dose if administered ≥8 years after the first Tdap dose and for use for tetanus prophylaxis when indicated for wound management if ≥5 years have elapsed since the previous receipt of any tetanus toxoid–containing vaccine 1.
- ACIP recommended that either Tdap or Td vaccines could be used in situations where only Td vaccine had been recommended, in light of the new indication for a second dose of Adacel and evidence of Tdap being used frequently in place of Td 1.
From the Research
Tdap Vaccine Administration
- The Tdap vaccine can be administered as soon as 2 years after the last tetanus vaccination for adults with infant contact and healthcare personnel with direct patient contact 2.
- For other adults, the Tdap vaccine can be administered if the most recent tetanus vaccination was ≥10 years prior 2.
- Studies have shown that Tdap can be safely administered at intervals of ≥18 months since a previous TD/Td vaccine 3.
- The safety of immunizing with Tdap less than 2 years following previous tetanus vaccination has been assessed, and the results suggest that it is safe to administer Tdap at this interval 4.
Interval Between Vaccinations
- The interval between Td/Td and Tdap vaccinations can be as short as 18 months without an increase in severe adverse reactions 3.
- A study found that the rates of moderate and/or severe injection site adverse events were not significantly greater in those vaccinated <2 years than in those vaccinated ≥2 years after previous Td/TT 4.
- Another study found that a second dose of Tdap vaccine 5 years after the initial dose was well tolerated and immunogenic in adolescents and adults 5.
Vaccine Efficacy and Safety
- Tdap vaccine has been shown to induce high seroprotective levels of antibodies to its three component acellular pertussis antigens in virtually all children and adolescents, and in a high proportion of adults and elderly individuals 6.
- The vaccine is safe and well tolerated in all age groups, with slight increases in injection site events with decreasing interval since a previous immunization 3, 4, 5.