VACCINE RESOURCE COMMITTEE

of the Edmonton Zone Medical Staff Association

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Diphtheria, Tetanus and Pertussis Vaccine Question #3:

Why do people need tetanus once every 10 years?

Additional doses are required once every 10 years to maintain immunity.

In Alberta the Tdap (adult booster) vaccine is recommended every 10 years. This vaccine is for tetanus, diphtheria, and pertussis. Protection from certain vaccines can wane over time, which is why doctors advise boosters. The tetanus vaccine is not only for tetanus. It's bundled with a vaccine for diphtheria and pertussis (the bacteria that causes whooping cough). These vaccines protect over 95% of people from disease for approximately 10 years.

A recent paper published in the journal Clinical Infectious Diseases suggested that tetanus and diphtheria booster vaccines are not necessary for adults who have completed their childhood vaccination series. This advice aligns with the current World Health Organization (WHO) recommendations. The researchers reviewed WHO data from 31 North American and European countries between 2001 and 2016, amounting to 11 billion person-years. (Person-years is a measurement that reflects the number of people in the study multiplied by years followed). After comparing the incidence of tetanus and diphtheria, they found no significant difference in disease rates in countries that require adults to receive booster shots compared with those that do not. Based on this, the authors suggest that childhood vaccination alone protects sufficiently against tetanus and diphtheria without booster vaccines.

The question of whether to have ongoing booster vaccines is more complicated than looking at frequency of a disease. The conclusions of this study focus on the lack of change in tetanus or diphtheria incidence rates among countries that routinely vaccinate children. However, other factors influence the number of cases, such as the overall amount of the bacteria in the environment, or wound management and hygiene measures.

Immunity from antibodies to tetanus and diphtheria may persist for many years. Over time, though, antibody levels decrease. Even if antibodies are present, low levels may not always be protective. Even though this study was well executed and raises some important questions, further studies are needed to examine whether a childhood vaccination series offers lifelong protection without repeated adult boosters.

Even though it happens rarely, people can still get tetanus and experience serious or deadly effects. There is no cure for tetanus, and no definitive proof that you will have lifelong immunity with childhood vaccinations alone. So for now, the CDC continues to recommend booster vaccines every 10 years to help your immune system protect against these infections. 

Sources:

Alberta Health Services: Tetanus, diphtheria, acellular pertussis (Tdap) vaccine 
Harvard Health Publishing: Do adults really need tetanus booster shots?