Tetanus shots are not vaccines; they are a type of passive immunization. To understand this, we need to know about the pathogenesis of tetanus. Tetanus infection generally refers to an infection by Clostridium tetani, an anaerobic bacterium that proliferates and grows in wounds and can produce exotoxins, leading to corresponding clinical symptoms in patients. Therefore, tetanus shots include tetanus antitoxin and tetanus immunoglobulin. Their main function is to neutralize the bacterial exotoxins, hence they are considered passive immunization agents and belong to the antibody category, not vaccines.