The investigators of a new observational cohort study on incidence of tetanus and diphtheria in 31 countries have provided data that suggest no benefit associated with performing adult booster vaccinations.
Before vaccines were introduced, there were hundreds of tetanus-associated deaths and nearly 2000 diphtheria-associated deaths in the United States annually. Now, there are extremely few.
In February 2020, the US Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP) published its 2020 adult immunization schedule.
Among the changes relative to past ACIP schedules were measures which increase provider flexibility around tetanus and diphtheria vaccination, allowing certain vaccines to be used interchangeably in some cases.
The ACIP continues to recommend that tetanus, diphtheria, pertussis vaccines be administered to adults in booster doses every 10 years. However, the World Health Organization (WHO) does not recommend routine adult booster vaccination for these infectious diseases after an individual completes the childhood vaccination series.
The investigators of a new observational cohort study assessing the incidence of tetanus and diphtheria in 31 countries have provided data that suggest no benefit associated with performing adult booster vaccinations. The study was published in Clinical Infectious Diseases.
"To be clear, this study is pro-vaccine," said study author Mark Slifka, PhD, professor at the Oregon Health & Science University School of Medicine, in a press release.
"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 study team used data obtained from the WHO Vaccine-Preventable Diseases Monitoring System collected from 2001 through 2016. They compared incidence of tetanus and diphtheria in 31 European and North American countries.
The investigators made an initial close comparison of 2 large sized, socioeconomically similar European countries. The United Kingdom has never recommended adult booster vaccination for tetanus and diphtheria, whereas France has an adult booster recommendation.
It was discovered that despite an adult booster vaccination program in France which documented nearly 80% compliance, there was not a decline in tetanus incidence compared to the United Kingdom.
Expanding the analysis to the full range of countries studied validated the findings. The comparison of countries which vaccinate adults every 5-20 years with those that do not revealed no significant decline in tetanus incidence among countries that vaccinate adults.
By initial study parameters it would appear that adult vaccination actually increased rates of diphtheria incidence. However, this was due to the inclusion of Latvia, which had poor vaccine coverage among both adults and children.
Once Latvia was removed from the adult booster group of countries, it was apparent that there was likewise no significant difference between the groups.
The findings could be beneficial in refocusing vaccine efforts toward at-risk groups.
“Review of >11 billion person-years of incidence data revealed no benefit associated with performing adult booster vaccinations against tetanus or diphtheria. 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 health care resources on vulnerable and undervaccinated populations,” study authors wrote.