For generations, adults in the U.S. have been told to roll up their sleeves for a tetanus and diphtheria booster every 10 years. But new research from Oregon Health & Science University suggests this long-standing advice may be outdated — and unnecessarily costly.
In a study published Tuesday, OHSU scientists argue that adults who completed their childhood vaccinations may not need tetanus or diphtheria boosters nearly as often as previously thought. Their findings suggest protection lasts far longer for most healthy adults — at least 30 years, and possibly for life.
“Why keep vaccinating adults every 10 years? It’s just burned into our brains when the evidence shows you don’t have to,” said lead author Dr. Mark K. Slifka, a professor at OHSU’s Oregon National Primate Research Center.
The U.S. has recommended a 10-year booster schedule for tetanus-diphtheria since the 1960s. But Slifka said this guidance hasn’t kept pace with mounting evidence that immunity to these diseases — now rare in the U.S. thanks to widespread childhood vaccination — doesn’t require such frequent upkeep.
“Tetanus and diphtheria are among our most successful vaccines,” he said. “Their effectiveness has virtually eliminated these diseases in countries with high childhood vaccination coverage.”
Tetanus, a severe bacterial disease caused by spores commonly found in soil, manure or dust, now occurs in the U.S. at a rate of less than one case per 10 million people annually. Diphtheria, a highly contagious bacterial infection, is even more rare, with just seven cases reported nationwide over the past 20 years.
Oregon’s last tetanus case occurred in 2017, when an unvaccinated 6-year-old boy nearly died after scraping his forehead. Before that, the state hadn’t seen a case in 30 years.
Slifka’s latest study, published in the journal Clinical Microbiology Reviews, builds on nearly two decades of research tracking immunity in individuals and across populations. His findings suggest that for adults who received the standard five-dose childhood vaccine series, immunity often lasts for life — making routine boosters largely unnecessary.
Based on the evidence, the researchers propose a simpler, age-based schedule: a booster at age 30 and another at 60. They say that would eliminate the confusion and burden of trying to recall the date of one’s last shot every decade.
Slifka said “this idea isn’t a radical change,” as similar policies exist abroad. The United Kingdom, for example, doesn’t recommend routine adult boosters and has maintained low rates of both diseases, even during a 2022 influx of more than 70 diphtheria cases.
The World Health Organization dropped its recommendation for routine adult boosters in 2017, advising them only in specific circumstances such as pregnancy, travel, or wound care.
Meanwhile, more than 18 million Americans receive these boosters annually, costing over $1 billion. The researchers say a 30-year schedule could cut vaccination costs by two-thirds, saving around $280 million each year.
Slifka said eliminating unnecessary boosters — while continuing vaccinations for pregnant women, people with wounds and those with uncertain vaccine history — could free up resources for other public health priorities.
“If we could use some of these funds that we save and use it to deal with vaccine hesitancy and vaccine education, then I think we could really put that money to good use,” he said.
Slifka said that while the study suggests boosters may not be needed as often, it should not be seen as a reason to overlook the importance of childhood vaccinations.
“Vaccines work, and they work for a long time,” he said. “By maintaining strong, consistent childhood vaccination programs, we’re able to reduce or eliminate these booster vaccinations for adults.”
Changes to official guidelines would require review by the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices, the group responsible for setting vaccine policy in the U.S.
Slifka hopes this new evidence sparks a fresh look.
“The wheels of science turn slowly,” he said. “But we think it’s time to bring this back up for discussion.”
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