No Need for Adult Booster Shot for Tetanus or Diphtheria in Many Countries

By Marilynn Larkin

March 06, 2020

NEW YORK (Reuters Health) - There is no evidence that adult booster vaccinations for tetanus and diphtheria are beneficial, researchers say.

"Although the U.S. guidelines currently recommend adult booster vaccination every 10 years, the World Health Organization does not recommend adult booster vaccination once the childhood series has been completed," Dr. Mark Slifka of Oregon Health and Science University in Beaverton told Reuters Health by email. "When we compared countries that do or do not routinely vaccinate, we found no significant difference in the incidence of either of these two rare diseases."

Further, he said, "the reduction in routine booster vaccination could save approximately $1B/year in the U.S. alone, in addition to reducing unnecessary vaccine-associated adverse events."

"We are hoping that the Advisory Committee on Immunization Practices will review these recent findings and make a decision on whether or not to harmonize the U.S. recommendations with the WHO recommendations," he added.

Using WHO case reports from 2001-2016, Dr. Slifka and colleagues compared the incidence of tetanus and diphtheria in 31 North American and European countries with or without a recommendation for adult booster vaccination.

Specifically, countries that vaccinate adults every 5-20 years were compared with countries that do not routinely vaccinate adults for tetanus or diphtheria.

As reported in Clinical Infectious Diseases, the review of 13.4 billion person-years of incidence data revealed no significant decline in tetanus incidence rates among countries that vaccinate adults (risk ratio, 0.78).

The risk of contracting diphtheria was increased among countries that vaccinate adults due to inclusion of Latvia, a country with poor vaccination coverage. After excluding Latvia, there was no difference in diphtheria incidence between countries that do or do not routinely vaccinate adults (RR, 2.46).

The authors conclude, "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."

Dr. Slifka said, "There are always a few exceptions to the rule." Specifically, adults who may need a second vaccination include those who are unsure of their vaccination history; pregnant women, for whom a booster vaccination with DTaP is recommended to reduce the risk of neonatal tetanus in developing countries and the risk of whooping cough, through the transfer of maternal antibodies to the infant; for wound management, in which case patients should follow the advice of their physician; and for international travel to countries/regions with active diphtheria outbreaks.

"This work is based on 31 countries in North America and Europe that have good healthcare infrastructure, high childhood vaccination coverage, and low incidence of either tetanus or diphtheria," he noted. "Low- and middle-income countries that do not yet have high vaccination coverage or are unclear in terms of their current incidence rates will need to gather this information before they consider modifying their adult vaccination schedules."

Infectious Diseases Society of America spokesperson Dr. Aaron Eli Glatt, chair of medicine at Mount Sinai South Nassau in Oceanside, New York agrees with the findings. "In a situation where a person has a high-risk injury for tetanus, an individual decision must be made regarding whether a supplemental dose of a vaccine is appropriate," he told Reuters Health by email.

"If they have received a tetanus vaccination in the recent past, no additional vaccination would be necessary," he noted. "If their last vaccination was not within 10 years, and it was a high-risk injury, or in a situation where the vaccination history was unclear, an additional dose of vaccine would be potentially appropriate."

Dr. Terry Krause of UCHealth Primary Care in Castle Rock, Colorado, commented in an email to Reuters Health, "I would interpret the IDSA conclusion cautiously. It is not known which adult populations need tetanus and diphtheria boosters. Herd immunity remains an important protective force for vulnerable populations. Adults are often in close contact with children and immune-compromised individuals who could suffer greatly if the transmission of diphtheria, for example, increases."

"We at UCHealth Primary Care will continue to follow the U.S. CDC vaccination schedule for adults, which dictates a Td or Tdap booster every 10 years," she concluded.

SOURCE: Clinical Infectious Diseases, online February 25, 2020.