Post-Exposure Prophylaxis (PEP) involves taking anti-HIV medications within the first 72 hours after you have been exposed to HIV. Application of PEP reduces the chance of becoming HIV positive. PEP medications keep HIV from multiplying itself and spreading through your body.
PEP may be used on anyone who may have been exposed to HIV during a single event of sex.
One can be put on PEP treatment if he/she has been exposed to HIV after getting cut/ stuck with a needle that was used to draw blood from a person who is HIV positive.
For medical workers, they can get HIV while getting blood or other body fluids from an HIV positive person. The risk of getting HIV infection is low when one is on PEP.