Tetanus-Diphtheria Boosters: Is 10 Years Too Soon to Boost?
Amesh A. Adalja, MD, FACP, FACEP, FIDSA, May 13, 2016
Most medical students, by the time they graduate, have the association between 10 years and the need for a tetanus-diphtheria (Td) booster ingrained in their heads. However, there has been evidence that suggests this interval may be too short, as long-lived immunity persists. The UK, in contrast to US vaccine policy, does not recommend any Td boosters after the primary vaccine series has been completed. A new study by Hammarlund and colleagues at the Oregon Health and Science University adds important data to the debate regarding the optimal interval for tetanus-diphtheria booster shots.
72 Years of Protection Against Tetanus
In this study, which was conducted from 2002 to 2008, 546 individuals were recruited and measurements were taken of the magnitude and duration of immunity to both tetanus and diphtheria. Antibodies were measured with attention to age as well as time since last vaccination.
The authors found the half-life of anti-tetanus antibodies to be 14 years, and, based on the duration that protective antibody levels (0.01 IU/mL) persist, it was estimated that 95% of the population would be protected from tetanus for 72 years without further boosters.
Diphtheria antibodies decayed with a similarly long half-life of 27 years and were estimated to persist above protective levels (0.01 IU/mL) for 42 years without the need for boosting.
Sparing the Needle
This study is important and will likely begin to shift vaccine booster recommendations. Based on their estimates, Hammarlund and colleagues distill their research into a reasonable policy recommendation to replace the 10-year requirement with a simplified schedule that includes a pertussis-containing booster at age 30 and a Td at age 60. Such a policy shift would greatly simplify vaccination schedules, minimize injection site reactions, diminish relatively rare serious vaccine effects (eg, anaphylaxis), and avoid the inevitable confusion that occurs when patients present to emergency departments with lacerations and puncture wounds and can’t remember when they received their last tetanus shot.
Hammerlund E, Thomas A, Poore EA, et al. Durability of vaccine-induced immunity against tetanus and diphtheria toxins: a cross sectional analysis. Clin Infect Dis 2016;62:1111-1118.