Updated recommendations for the use of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine have been developed by the Advisory Committee on Immunization Practices (ACIP) and are now published in Morbidity and Mortality Weekly Report. These updates, which address the acceptability in use of the tetanus and diphtheria toxoids (Td) vaccine across multiple scenarios, and now allow either Tdap or Td to be used in multiple situations, will increase provider point-of-care flexibility.

In September 2018, the ACIP Pertussis Vaccines Work Group began to review Tdap vaccination recommendations. Clinical trials published between January 2013 and June 2019 assessing Tdap vaccination in adults and adolescents with previous Tdap immunization were reviewed. A summary of the key findings, rationale, and recommendations is outlined below.

Summary of Key Findings

Safety and immunogenicity: Two clinical trials found no increased risk for adverse events among adults who received Tdap compared with adults who received Td 10 years after initial Tdap dose. Evaluations of seroprotectivity for tetanus and diphtheria were similar in both the Tdap and Td groups.

Another clinical trial that compared the effects of the administration of Tdap booster vaccine after the initial Tdap vaccination with the effects of the administration of solely the initial Tdap vaccine. Results found that the most common adverse events (injection site pain, fatigue, and headache) were higher in those receiving a second dose of Tdap, while grade 3 adverse events —pain, headaches, fatigue, redness and swelling, fever, and gastrointestinal symptoms — were similar across both groups.

Current data regarding the use of >1 Tdap dose in catch-up immunization schedules are limited. In one clinical trial, 460 adults who had either an unknown vaccination history or who had not received a diphtheria or tetanus vaccination for ≥20 years, were randomly assigned to receive either 3 doses of a Tdap formulation, 1 Tdap-inactivated polio vaccine combination dose followed by 2 Td doses, or 3 Td doses at 0, 1, and 6 months. No significant difference in adverse events or diphtheria and tetanus seroprotection rates were noted among the 3 groups.

No published data exist comparing rates of adverse events among pregnant women receiving multiple Tdap doses during a single pregnancy compared with those who received a single Tdap dose in conjunction with additional Td doses for catch-up vaccination.

Health and economic considerations: Currently, Tdap costs more than Td. The ACIP has reviewed the population-level effectiveness and economic effects of replacing Td with Tdap; results suggest that cost-effectiveness estimates are “dependent on values for parameters with a high degree of uncertainty,” according to guideline authors.

Recommendation Rationale

In the 2019 iteration, the ACIP recommendations concurred with its 2013 decisions, which noted due to the higher cost of Tdap, and the uncertainty regarding the effect of multiple Tdap doses on control and transmission of pertussis, evidence was insufficient to preferentially recommend that Tdap replace Td for second-dose purposes.

However, recent reassuring safety profiles and evidence demonstrating the widespread use of Tdap in place of Td, the ACIP now recommends that either Tdap or Td may administered for the 10-year booster for tetanus prophylaxis, thus allowing clinicians more flexibility.

General Recommendations

Individuals aged 11 to 18 years should receive a single Tdap dose at a preventive care visit; preference was highlighted that this initial vaccine should be adminstered between ages 11 and 12. One booster dose of either Td or Tdap should be administered every 10 years thereafter to ensure continued protection.

Individuals aged >19 years who have never received Tdap should receive 1 dose of Tdap. To ensure continued protection, booster doses of either Td or Tdap should be administered every 10 years thereafter.

Recommendations for routine Tdap immunization during pregnancy remain the same: Pregnant women should receive 1 Tdap dose during each pregnancy regardless of their previous vaccination history. The vaccine should be administered between 27 and 36 weeks gestation.

Recommendations for Tetanus Prophylaxis for Wound Management

A tetanus toxoid-containing vaccine is indicated for wound management in patients who have a longer than 5-year period since the last tetanus toxoid-containing vaccine dose. Tdap is the preferred formulation for this use of the vaccine in patients ≥11 years, those who have not previously received Tdap, those with an unknown history, and pregnant women. For those with previous Tdap vaccination, either Td or Tdap may be used.

Recommendations for Catch-up Immunization

For individuals aged >7 years who have not been vaccinated against pertussis, tetanus, or diphtheria should receive a series of 3 tetanus and diphtheria toxoid-containing vaccines, including at least 1 Tdap dose. The recommended schedule is 1 dose of Tdap followed by 1 dose of either Td or Tdap ≥4 weeks later, and 1 dose of either Td or Tdap 6 to 12 months later.

Among individuals aged 7 to 18 years who have an incomplete diphtheria and tetanus toxoids and acellular pertussis (DTaP) history, the ACIP noted that the series does not need to be restarted. For those aged >19 years, who have not been fully immunized against tetanus and diphtheria should receive 1 dose of Tdap; either Td or Tdap may be used if additional tetanus toxoid-containing doses are required.

Individuals aged 7 to 9 years who receive Tdap as part of a catch-up series should receive an adolescent Tdap dose at age 11 or 12 years. If Tdap is administered at age ≥10 years, the dose may count as the adolescent Tdap dose.

Recommendations for the Prevention of Neonatal and Obstetric Tetanus

For the prevention of neonatal tetanus, pregnant women who have completed their childhood immunization schedule and who were last vaccinated >10 years prior should receive a booster dose of a tetanus toxoid-containing vaccine. Neonatal tetanus risks are minimal if a woman who was previously unvaccinated receives >2 properly spaced doses of a tetanus toxoid-containing vaccine during pregnancy, including at least one dose of Tdap.

Recommendations for Inadvertent Administration

The DTaP vaccine is not indicated for individuals aged >7 years. If DTaP is inadvertently administered to a fully vaccinated child between aged 7 to 9 years, an adolescent Tdap dose should be administered between age 11 and 12 years. If DTaP is administered inadvertently to an undervaccinated child between ages 7 and 9 years, this dose should count as the Tdap dose of the catch-up series, and the child should receive an adolescent Tdap dose between ages 11 and 12. In those aged >10 years, the inadvertent dose should count as the adolescent Tdap dose administered routinely between ages 11 and 12 years.

Tdap doses administered to fully vaccinated children ages 7 to 9 years should not be counted as valid, and the adolescent Tdap dose should be administered when the child reaches age 11 or 12 years.

Recommendations for Off-Label Use

Off-label indications based on age and pregnancy status have not changed.

For Adacel (Sanofi Pasteur), new off-label indications include any additional routine or catch-up doses of Td, beyond a second dose administered ≥8 years after an initial Tdap dose and not given for wound prophylaxis. For Boostrix (GlaxoSmithKline), any additional doses administered beyond the single licensed dose are considered off-label.

Contraindications and precautions remain unchanged from previous recommendations. Adverse events following the administration of any vaccine should still be reported to Vaccine Adverse Event Reporting System.

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“ACIP will continue to review data on Td and Tdap as they become available, examine the necessity and frequency of booster doses for protection against tetanus and diphtheria, and consider any needed policy changes,” the researchers concluded.

Reference

Havers FP, Moro PL, Hunter P, Hariri S, Bernstein H. Use of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccines: Updated recommendations of the Advisory Committee on Immunization Practices — United States, 2019. MMWR Morb Mortal Wkly Rep. 2020;69(3):77-83.

This article originally appeared on Infectious Disease Advisor