How deep does a cut have to be to get tetanus?

Tetanus: While any open wound can be a source of tetanus, it is more common in wounds contaminated by dirt, feces, soil or saliva. It is also more like to occur as a result of puncture wounds, crush or avulsion injuries, burns, or necrotic/devitalized tissue. It is always wise to be current on vaccinations and if a person is behind who has an open wound, call your physician to get them updated.