Immunologic response to a single dose of tetanus toxoid in older people.
OBJECTIVE
Several studies have demonstrated that a large percentage of older people are inadequately immunized against tetanus. The aim of this study was to assess the immunity against tetanus in a group of individuals aged 69 and older and to examine the immune response to a single dose of tetanus toxoid.


METHODS
A convenience sample of 115 residents of a large retirement home, aged 69 and older, was studied. After a blood sample for anti-tetanus antibody titer, a single dose of tetanus toxoid vaccine was administered. Repeat titers were obtained 6 weeks after the vaccination and analyzed by ELISA assay. Antibody levels equal to or greater than 0.1 IU/mL were considered protective.


RESULTS
Sixty-seven of 115 (58.3%) individuals had adequate antibody titers. Those individuals who reported having been vaccinated with tetanus toxoid in the past were more likely to be immunized adequately compared with those who reported having never been vaccinated (66.7% vs 39.3%, P = .02). After vaccination, 34 of 46 (73.9%) individuals with inadequate antibody titers became seropositive. Those who remained seronegative had mean prevaccination antibody titers significantly lower than those who seroconverted. Sixteen of 17 (94.1%) persons who reported having been vaccinated in the past and were found to be seronegative developed adequate antibody titers following vaccination, compared with only nine of 16 (56.2%) who reported never having been vaccinated (P = .04). There was no association between seroconversion rate and age, sex, underlying diseases, and army service.


CONCLUSIONS
Most individuals will develop an adequate anti-tetanus antibody titer following administration of a single dose of tetanus vaccine. A history of past immunization is a good predictor of becoming adequately immunized. It is important that physicians follow the current recommendations for adult immunization and initiate campaigns to ensure that the older population is protected against tetanus.
Shohat
T
T
Tel-Aviv Health District and the Department of Epidemiology and Preventive Medicine, Tel-Aviv University, Israel.
Marva
E
E
Sivan
Y
Y
Lerman
I
I
Mates
A
A
Cohen
A
A
D000368:Aged / Q000706:statistics & numerical data*; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood / Q000276:immunology; D000907:Antibodies, Bacterial / Q000097:blood*; D003017:Clostridium tetani / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005500:Follow-Up Studies; D017408:Guidelines as Topic; D016852:Housing for the Elderly; D006801:Humans; D007115:Immunization Schedule; D007117:Immunization, Secondary; D007557:Israel; D008297:Male; D011795:Surveys and Questionnaires; D013745:Tetanus Toxoid / Q000276:immunology*
D000907:Antibodies, Bacterial; D013745:Tetanus Toxoid