Fun Fact: There are 2 main conditions to catch tetanus:
1, the rusty metal must be in a place where it is exposed to (usually farm) animal excrement because tetanus comes from feces.
2, the wound must not be oxygenated. This means the wound must not be bleeding, like a splinter, otherwise the tetanus cannot survive.
If it doesn't have both of these conditions met it is physically impossible to catch it. Additionally, the tetanus vaccine claims that the vaccine only begins working after 3 weeks, by this point tetanus would have already set in, rendering a preventative measure void. It's still wise to be careful with sharp objects though!