Comment by simonask
10 hours ago
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.
At least 2 hours before, not 1, and preferably closer to 24 hours before.
Does this double dose completely prevent infection?
The evidence I’m aware of suggests that this method (on-demand or event-based PrEP) is broadly as effective as daily PrEP (though it’s not suitable for vaginal sex). I believe adherence rates are generally lower though, as people can find the instructions confusing, and it’s obviously easier to mis-dose than a daily regimen.