4 Reasons Tetanus-Diphtheria Booster Shot Should Be Given Every 30 Years

Imagine a world where tetanus and diphtheria (Td) booster vaccines are administered every 30 years instead of every 10.

That’s what a new study published in Clinical Infectious Diseases suggests could be possible.

The Advisory Committee on Immunization Practices (ACIP) will need to review the evidence and make a ruling before the vaccine booster schedule can be changed, but lead study author Mark K. Slifka, PhD, a professor from the Oregon Health & Science University, is optimistic.

“I am hoping that they [ACIP] will review it later this year and hopefully come to the same conclusion that we did: that immunity is much more long-lived then we realized and that we can shift from a 10-year to a 30-year vaccination schedule without a loss in protective immunity,” Dr. Slifka told Pharmacy Times.

Dr. Slifka and his fellow researchers examined the levels of immunity in nearly 550 adults and discovered that antibody titers against tetanus and diphtheria lasted longer than previously thought.

They found that antibody magnitude and duration predicted that 95% of the population could be protected against the 2 infections for 30 years without booster shots.

The researchers proposed a new Td booster vaccination schedule under which adults are vaccinated at age 30 years and 60 years. They argued that vaccine schedules should be based on immunological and epidemiological data and risk-benefit analysis instead of “conformity to historical convention.”

One especially surprising finding was the durability of the vaccine-induced immune responses among elderly patients, Dr. Slifka said.

“It is well-known that it is harder to vaccinate older individuals, but there is very little known about how well they will maintain long-term immunity after they have been successfully vaccinated,” he said.

However, the researhcers found that the durability of antibodies to tetanus and diphtheria in older patients were the same compared with younger patients.

“This means that once a strong immune response is developed, it won't decline faster just because you are over the age of 50 or 60,” Dr. Slifka said. “And that was a very interesting result that we had not anticipated.”

Here are 4 reasons why a 10-year vaccination schedule for Td should be considered:

1. Fewer patients would experience adverse effects related to the administration of the vaccines.

The researchers emphasized that the vaccines have “a long safety history,” but some patients do experience adverse effects associated with them.

Between 50% and 85% of patients experience pain or tenderness at the injection site, and 25% to 30% experience edema and erythema. In addition, those with already high anti-tetanus antibody levels tend to have higher, more severe reactogenicity.

Meanwhile, anaphylaxis is estimated to occur around 1.6 cases per million doses, and brachial plexus neuropathy happens at a rate of 5 to 10 cases per million doses.

“Because overimmunization provides a negligible increase in protection, this suggests that the risk-benefit ratio of a decennial adult booster vaccination schedule should be reexamined,” the researchers wrote.

2. In other areas of the world, adults who were immunized as children don’t need to get booster shots.

The United Kingdom doesn’t require Td booster shots for adults if they completed the 5-dose immunization series as children. In addition, the World Health Organization recommends a booster shot only during military service and a woman’s first pregnancy.

“The safety and success of more moderate European vaccination programs with longer intervals between booster vaccinations indicate that the current 10-year booster vaccination schedule should be reexamined,” the researchers wrote.

3. A simplified vaccination schedule could improve compliance.

If the Td vaccination schedules were changed to booster shots at age 30 and 60 years, patients may be more compliant, since getting vaccinated every 30 years is easier to do than every 10 years.

In addition, the researchers pointed out that patients in their early 60s already have to get the varicella zoster virus vaccine, so the vaccines could potentially be administered at the same visit.

4. Health care costs would drop.

Around 63% to 64% of adults self-report that they adhere to the 10-year tetanus and diphtheria revaccination schedule. This would mean that around 150 million adults have been vaccinated in the last decade, and around 15 million doses are administered per year.

Based on the CDC’s vaccine price list, Td booster vaccinations cost $420 million per year ($28 per dose).

“If this were changed to a 30-year schedule, then the costs would be reduced by two-thirds, equating to a reduction of approximately $280 million per year in health care costs,” the researchers posited.

In other words, there could be around $1 billion in cost savings in 4 years.