No, PrEP is not a vaccine. A vaccine provides immunity against an illness for a long period of time with no daily upkeep. PrEP is a daily pill that, when taken as prescribed, greatly reduces your risk of getting HIV. PrEP does not provide immunity against HIV; as soon as you stop taking PrEP, you lose protection against the HIV virus. PrEP must be taken every day for optimal protection against HIV.