Question · from the living review of Hiv Pharmacotherapy →

Is it true that daily oral tenofovir-based pre-exposure prophylaxis (PrEP) reduces HIV acquisition risk by 99% in adherent individuals, with effectiveness dependent on adherence?

Established updated weekly · as of

Priors rates this Established — 93 out of 100, updated weekly. Yes — this looks well established. On the claim that daily oral tenofovir-based pre-exposure prophylaxis (PrEP) reduces HIV acquisition risk by 99% in adherent individuals, with effectiveness dependent on adherence, its four-agent AI review panel weighs 7 primary peer-reviewed studies.

RefutedDoubtfulUncertainLikelyEstablished
where this sits on Priors’ scale of how settled the evidence is

How we got this answer. Priors runs each claim through a panel of four AI agents, each acting as a specialist expert reviewer. They read the published, peer-reviewed studies behind the question, judge how strong, consistent and reliable the evidence is, and turn that judgment into a single rating from 0 to 100 — refreshed every week as new studies appear, so it reflects where the evidence stands today, not a one-off verdict.

The traceable studies behind this rating — and the panel’s single strongest counter-argument to it — are in Priors’ full Hiv Pharmacotherapy review.

Related Infectious Disease questions

Is it true that people living with HIV on effective ART with an undetectable viral load do not transmit HIV sexually (U=U: Undetectable = Untransmittable), as demonstrated across multiple large prospective studies? → Is it true that antiretroviral therapy (ART) suppresses HIV viral load to undetectable levels in the majority of adherent patients, restores CD4 count, and prevents AIDS-defining illness and death? → Is it true that dolutegravir-based regimens are superior or non-inferior to other antiretroviral classes as first-line therapy in terms of virological suppression, tolerability, and barrier to resistance? → Is it true that two-drug regimens (dolutegravir/lamivudine; dolutegravir/rilpivirine) are non-inferior to standard three-drug regimens for virologically suppressed patients and reduce drug burden without compromising efficacy? →
Reflects the peer-reviewed evidence as of 17 July 2026 and updates as new studies land. AI can make mistakes. Not medical advice.