Neil M. Ampel, MD reviewing Hammarlund E et al. Clin Infect Dis 2016 May 1.
Immunization against tetanus and diphtheria is so effective that concern about vaccine-related adverse events associated with booster vaccinations has assumed greater importance. Currently, repeat immunization in the U.S. is recommended every 10 years for those aged >6 years, but longitudinal studies have suggested that antibody titers last far longer than this interval. In a cross-sectional study, researchers in Oregon analyzed tetanus and diphtheria toxin-specific antibody levels among 546 adults recruited from 2002 to 2008.
In 97% of the study population, both tetanus-specific and diphtheria-specific antibody concentrations were above the protective level of 0.01 IU/mL. A regression model estimated that, without further booster vaccination, 95% of the population would remain protected against tetanus for up to 72 years and against diphtheria for up to 42 years. While subjects aged 50 or older had lower antibody titers to both tetanus and diphtheria than younger subjects, antibody half-lives were the same in the older and younger groups.
These results indicate that protective antibody responses against both tetanus and diphtheria are very long-lived and persist well beyond the currently recommended 10-year interval for booster vaccination. As the authors note, the lower antibody titers in older individuals could be due to incomplete initial vaccination or to immune senescence. A new approach could be to provide a booster vaccination at age 30 that also included acellular pertussis (i.e., Tdap) followed by another booster at age 60.
Personal comment: This is a very important study. After injury, there is sometimes nearly a panic over getting the Tetanus vaccination “in time”. Patients get needlessly sent to other medical centers where they have the vaccine. This paper nullifies the need for the booster, in someone who got the full initial series of shots.
Hammarlund E et al. Durability of vaccineinduced immunity against tetanus and diphtheria toxins: A crosssectional analysis. Clin
Infect Dis 2016 May 1; 62:1111. (http://dx.doi.org/10.1093/cid/ciw066) Abstract/FREE Full Text