Vaccines are used to prevent illness. Most vaccines are given as injections or shots. Before a doctor gives a patient a shot, the doctor wipes the skin with rubbing alcohol. What is the main reason for wiping off the skin?

If there is bacteria on your skin, inserting a syringe into it may cause the bacteria to enter your body and into your bloodstream (can lead to blood poisoning). By using rubbing alcohol on your skin before getting a vaccination, the bacteria dies, and you're skin gets disinfected.