Review suggests ending adult boosters for tetanus, diphtheria

(Press-News.org) The United States could safely drop tetanus and diphtheria booster shots for adults and save an estimated $1 billion a year, according to a new review led by researchers at Oregon Health & Science University.

The safety and savings depend on maintaining strong childhood vaccination rates, researchers emphasized.

“By maintaining high childhood vaccination coverage, we not only protect kids, but we may actually be able to reduce adult booster vaccinations,” said lead author Mark Slifka, Ph.D., professor of microbiology and immunology in the OHSU School of Medicine and the Oregon National Primate Research Center. “That would save $1 billion a year in the U.S. while maintaining the safety and protection of the general population.”

Slifka noted that dropping the 10-year schedule for adult boosters would more closely match guidelines recommended by the World Health Organization.

The review bolsters previous OHSU research in 2016 and in 2020 that concluded the combined vaccine produced at least 30 years of immunity, well beyond the current recommendation of every 10 years for adults from the U.S. Centers for Disease Control and Prevention. The vaccine is usually given as a combined tetanus, diphtheria and pertussis vaccine, known as DTaP.

In the U.S., childhood vaccinations are recommended six times, from infancy through age 12.

The new review suggests doing away with adult boosters altogether, as long as childhood vaccination rates remain high and the vaccine remains available on a case-by-case basis. For example, it may be necessary for someone injured in a workplace accident or car crash to receive a tetanus booster.

A natural experiment in the U.K. and France

Published today in the journal Clinical Microbiology Reviews, the review highlights a comparison between two industrialized countries just 21 miles across the English Channel: France and the United Kingdom. Both countries have excellent childhood vaccination coverage, similar to the U.S.

“This represents sort of an experiment of nature,” Slifka said.  “We have one country with over 60 million people that for decades has continued to vaccinate adults throughout their lifetime and another nearby country that also has over 60 million people, but over the past 50 years, they have never recommended adult booster vaccinations.

“The question we asked is, ‘What happens if we don’t vaccinate the adults? Are there more cases of disease or are these people protected after completing their childhood vaccination series?’”

Similar to the United States, France has a recommended booster vaccination schedule for adults. In contrast, except during pregnancy or for wound management, the United Kingdom hasn’t recommended boosters for tetanus and diphtheria beyond age 14 since the 1950s.

Yet, despite decades of adult booster vaccination, the review found that France had virtually no advantage over the U.K. in the rates of tetanus or diphtheria. In fact, the review found that the UK had a slightly lower rate overall.

In addition, “herd immunity” held strong even in 2022 when the U.K. reported an outbreak of 73 imported diphtheria cases among immigrants seeking asylum. This spike in cases was almost equal to the total number of diphtheria cases reported in the entire country over the previous 20 years combined.

“Remarkably, despite this proportionally large influx of imported diphtheria cases, there was no evidence of transmission reported among other asylum seekers who arrived by other routes or among staff or health care workers,” the authors write.

The U.K. Health Security Agency concluded that the country’s current childhood-focused vaccination program is sufficient for preventing the spread of diphtheria and that the risk to the general UK population remains low.

Strong rates of childhood vaccination are critical

The findings highlight the remarkable durability of protection following childhood vaccination against a pair of diseases that were once all but a death sentence.

In 1948, the U.S. mortality rate for tetanus was 91%. Before the introduction of antibiotics and vaccines, the mortality rate for diphtheria was roughly 50%. To this day, diphtheria kills roughly one out of 10 people who aren’t vaccinated against it.

Today, the public health threat is diminished thanks to childhood vaccinations as well as booster shots recommended in pregnancy.

“Thanks to childhood vaccinations, these diseases are incredibly rare,” Slifka said. “In fact, you’re 10 to 1,000 times more likely to be struck by lightning than to be diagnosed with tetanus and diphtheria in the United States.”

In addition to Slifka, co-authors include Archana Thomas and Lina Gao, Ph.D., of OHSU; Ian J. Amanna, Ph.D., of Najít Technologies, and Walter A. Orenstein, M.D., of the Emory Vaccine Center at Emory University.

Research reported in this publication was supported by the Office of the Director of the National Institutes of Health, award number P51OD011092. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

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