My two-year-old brother stepped on a rusted staple yesterday, and he hasn't had the Tetanus shot yet. However, once there, we discovered that the local hospital didn't have the vaccination on hand, and they said we would need to see our family doctor. At first, the ER doctor said it would be fine to wait 24 hours. Then, when we mentioned the hospital was closed today, he said it would be okay for 48 hours. Assuming he was infected with the virus already, how long can he go without the vaccination? Or does vaccination even prevent the virus if the body is already infected?