Is Tetanus Shot Necessary After Getting Cut By Rusty Nail?

I sustained a cut from a rusty nail to my calf about 6 hours ago. The wound has started to show signs of infection (redness, slight swelling). I have only cleaned the wound with an antiseptic wash, and applied nothing else, nor taken any medication. Do I need a tetanus shot? I had a tetanus vaccine about 5 years ago last.