title: Durability of Vaccine-Induced Immunity Against Tetanus and Diphtheria Toxins: A Cross-sectional Analysis.
abstract: BACKGROUND
  Many adult immunization schedules recommend that tetanus and diphtheria vaccination be performed every 10 years. In light of current epidemiological trends of disease incidence and rates of vaccine-associated adverse events, the 10-year revaccination schedule has come into question.
  
  
  METHODS
  We performed cross-sectional analysis of serum antibody titers in 546 adult subjects stratified by age or sex. All serological results were converted to international units after calibration with international serum standards.
  
  
  RESULTS
  Approximately 97% of the population was seropositive to tetanus and diphtheria as defined by a protective serum antibody titer of ≥0.01 IU/mL. Mean antibody titers were 3.6 and 0.35 IU/mL against tetanus and diphtheria, respectively. Antibody responses to tetanus declined with an estimated half-life of 14 years (95% confidence interval, 11-17 years), whereas antibody responses to diphtheria were more long-lived and declined with an estimated half-life of 27 years (18-51 years). Mathematical models combining antibody magnitude and duration predict that 95% of the population will remain protected against tetanus and diphtheria for ≥30 years without requiring further booster vaccination.
  
  
  CONCLUSIONS
  These studies demonstrate that durable levels of protective antitoxin immunity exist in the majority of vaccinated individuals. Together, this suggests that it may no longer be necessary to administer booster vaccinations every 10 years and that the current adult vaccination schedule for tetanus and diphtheria should be revisited.
authors.affiliation: Division of Neuroscience, Oregon National Primate Research Center, Department of Molecular Microbiology and Immunology, Oregon Health & Science University.
authors.forename: Erika
authors.initials: E
authors.lastname: Hammarlund
authors.affiliation: Division of Neuroscience, Oregon National Primate Research Center, Department of Molecular Microbiology and Immunology, Oregon Health & Science University.
authors.forename: Archana
authors.initials: A
authors.lastname: Thomas
authors.affiliation: Najít Technologies,Beaverton.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Poore
authors.affiliation: Najít Technologies,Beaverton.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Amanna
authors.affiliation: Division of Neuroscience, Oregon National Primate Research Center, Department of Molecular Microbiology and Immunology, Oregon Health & Science University.
authors.forename: Abby E
authors.initials: AE
authors.lastname: Rynko
authors.affiliation: Biostatistics Shared Resource, Knight Cancer Institute.|Division of Biostatistics, Department of Public Health & Preventive Medicine, Oregon Health & Science University, Portland.
authors.forename: Motomi
authors.initials: M
authors.lastname: Mori
authors.affiliation: Division of Biostatistics, Department of Public Health & Preventive Medicine, Oregon Health & Science University, Portland.
authors.forename: Zunqiu
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Division of Neuroscience, Oregon National Primate Research Center, Department of Molecular Microbiology and Immunology, Oregon Health & Science University.
authors.forename: Mark K
authors.initials: MK
authors.lastname: Slifka
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood*; D000917:Antibody Formation; D003430:Cross-Sectional Studies; D004167:Diphtheria Toxin / Q000276:immunology*; D022422:Diphtheria-Tetanus Vaccine; D005260:Female; D006207:Half-Life; D006801:Humans; D007115:Immunization Schedule; D007117:Immunization, Secondary; D008297:Male; D008875:Middle Aged; D013744:Tetanus Toxin / Q000276:immunology*; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D004167:Diphtheria Toxin; D022422:Diphtheria-Tetanus Vaccine; D013744:Tetanus Toxin
keywords: cross-sectional analysis; diphtheria; immunological memory; tetanus