No need for adult tetanus, diphtheria boosters if fully vaccinated in childhood

Adults do not need booster shots for tetanus or diphtheria if they have already completed their vaccination course against these diseases during childhood, a study suggests. 

“The World Health Organization [WHO] does not recommend routine adult booster vaccination for tetanus and diphtheria after completion of the childhood vaccination series. However, many countries continue to implement adult booster vaccinations, leading to the question of whether this is necessary,” wrote the researchers. 

A review of >11 billion person-years of data showed that there was no benefit in lowering the incidence of tetanus or diphtheria with adult booster vaccinations, calling into question whether routine booster shots are necessary in these adults. [Clin Infect Dis 2020;doi:10.1093/cid/ciaa017] 

“To be clear, this study is pro-vaccine,” said principal investigator Professor Mark Slifka of the Oregon Health & Science University School of Medicine in Beaverton, Oregon, US. “Everyone should get their series of tetanus and diphtheria shots when they’re children. But once they have done that, our data indicates they should be protected for life.”

The observational cohort study compared the incidence of diphtheria and tetanus across 31 countries in North America and Europe that either recommended vaccination of adults every 5–20 years (group 1) or did not routinely vaccinate (group 2).

The researchers found that routine adult vaccination did not significantly reduce tetanus incidence rates (risk ratio [RR], 0.78; p=0.52).

Similar finding was seen for diphtheria incidence rates. While the risk of contracting diphtheria was higher among countries with routine adult vaccination, the researcher attributed this to inclusion of Latvia (which has poor vaccination coverage). Excluding Latvia in the analysis yielded no difference in diphtheria incidence among countries in group 1 vs group 2. (RR, 2.46; p=0.26).

Specifically, comparison of France and the United Kingdom, two adjacent European countries with similar childhood vaccination programmes and socioeconomic status revealed that adult booster vaccination was not associated with reduced disease incidence.

“We now have evidence showing the childhood vaccination series can provide a lifetime of protection against both tetanus and diphtheria,” said Slifka.

“Similar to other vaccines, this analysis supports the WHO position on adult booster vaccination and, if approved by governing health authorities, this may allow more countries to focus healthcare resources on vulnerable and undervaccinated populations,” the researchers added. “We estimate that removing the recommendation of decennial adult booster vaccination would save approximately $1.03 billion annually in healthcare costs in the US alone.”

Vulnerable populations, according to the researchers, referred to pregnant women and immigrants from nations with poor vaccination coverage, while undervaccinated populations include the elderly with unknown or incomplete vaccination schedules during childhood.

“In addition to routine/scheduled booster vaccinations, administration of tetanus- and diphtheria-containing vaccines may be recommended for certain types of international travel or as postexposure prophylaxis for tetanus-prone injuries in accordance with WHO recommendations or country-specific guidelines,” pointed out Slifka and co-authors.