immediate use after the person used the
razor, he cutted himself deep before with lots of blood on the
razor, you use it immediately after and cutted yourself deep too. Practically, it is so low to be warranted for testing (especially if you did not notice any blood of the razor and you did not cut yourself during shaving). But, the issue here, if you wish not to test, can you put this out of your mind? It's not healthy to keep on thinking about this.