Ignoring the importance of receiving booster doses of vaccines in vast major i- ty of adults could result in their lack of immunity against tetanus and dip h- theria. In this prospective cohort study all immunocompetent adults ≥ 40 years old who were admitted for any reason during the time period of the su rvey were enrolled and antibody levels against tetanus and diphtheria were measured. 84 patients (48%) were 40 - 60 years old and 93 (52%) subjects aged older than 60 years. In general, anti -tetanus antibody titer was <0.1 IU/m L (non- immune range) in 83 pe ople (46.9%). For anti - diphtheria antibody, 74 (41.8%) were considered non - immune. Of all people whose tetanus antibody level was <0.1, 19 had a complete history of childhood diphtheria and tetanus immunization and 64 had unknown vaccination history. Among people with diphtheria antibody levels < 0.1, 18 (24.3%) had complete history of childhood vaccination and 56 (75.6%) had unknown history.

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