Ad-hoc use of PrEP just requires that you take a double dose 1 hour prior to potential exposure, and follow up with another double dose 24 hours later, at least with the versions commonly prescribed to sexually active groups in my area.

I agree that a vaccine is another game-changer, but it’s extremely important that we don’t spread misinformation about the efficacy and convenience of PrEP. In developed societies, it has already all but eliminated new transmissions among groups that were previously most at risk.