Earlier quoted context omitted.
Isn’t prep more like a prophylactic, as opposed to a a vaccine? I’m more familiar with malaria, where the preventative medicines are currently more effective than the vaccines.
"Prophylactic" is a broad-enough word to encompass vaccines, as well, so I'm not sure what you're getting at. It just means something that defends against disease.
The distinction is that a vaccine will train your immune system to actively destroy the foreign body, while a prophylactics might just prevent it from spreading or taking hold to begin with.