What is the Risk of Disease Transmission when Sharing a Syringe but Switching Needle?

Sharing a syringe, even when using a new needle, is a direct violation of standard precautions. I agree that you should report the RN to the state medical board. If she is engaging in this type of reckless and risky behavior, it is likely that she is also taking shortcuts in other areas as well.  I see this in NYC all the time....advertised prices for 1/2 syringes, knowing that there is no such thing as a 1/2 syringe and clearly you are getting someone elses leftovers.  This activity needs to stop and that can only happen when the perpetrators are reported.

Sharing any syringes or needles is always a terrible idea and should never be done under any circumstances.  Whatever the risk is, it is clearly not worth it.