Toxoid Vaccines

Toxoids are inactivated toxins. In some instances, bacterial exotoxins are the sole or primary virulence factor and the strategy here is to immunise against the exotoxin not the actual bacterium. Tetanus toxin produced by Clostridium tetani is one such example. The bacterium is an obligate anaerobe widely distributed in the environment and is non-invasive.
Tetanus exotoxin is a very potent toxin which interferes with neuronal transmission and in extreme cases can prove fatal. Neonatal tetanus kills thousands of children each year. The problem is particularly acute in technologically underdeveloped countries, where home births in poor sanitary conditions are often the norm. The vaccine is highly effective in preventing the onset of tetanus. Diphtheria caused by infection with Corynebacterium diphtheriae, another common pathogen, is also prevented by use of a toxoid vaccine. Toxoid vaccines are expensive due to the large-scale cultures of organisms required to obtain exotoxin.