Pre-exposure prophylaxis for HIV prevention: Moving toward implementation

Cahill, Sean
Fenway Institute

Initial results from clinical prevention trials of pre-exposure chemoprophylaxis (PrEP) indicate that PrEP could be a key part of the
“game changer” needed to more effectively fight HIV. PrEP entails that
at risk HIV-uninfected people take antiretroviral medications to prevent
HIV transmission through unprotected sex or sharing needles. Oral PrEP
uses antiretroviral medications that are currently available for treatment.
A related experimental technology involves topical microbicides, a term
that can refer to any anti-infective agent, but in the current usage refers
to topical gels that contain anti-retroviral medications that are applied
vaginally or rectally to prevent HIV transmission. Future approaches to
the use of antiretrovirals for prevention include the use of intravaginal
rings or injectable medication. Some oral PrEP and topical microbicide trials have shown promise, while others have not. The use of pre-exposure prophylaxis (PrEP) for HIV prevention has shown efficacy with men who have sex with men (MSM) and heterosexuals. Biomedical
prevention interventions such as PrEP have great potential, especially if coupled with expanded testing, diagnosis, and linkage to earlier initiation of treatment and care (TLC ). Modeling demonstrates the most effective deployment of PrEP to slow the spread of HIV will be in combination with scaled-up treatment. PrEP must be accompanied by sustained care and behavioral interventions to ensure adherence, minimize risk compensation (people increasing risk because of anticipated protection), and monitor side effects and drug toxicities. Because many people who are at greatest risk to acquire HIV do not access regular clinical care, alternative implementation arrangements will be necessary. National monitoring systems are critical to preventing the spread of drug-resistant HIV. Some have raised concerns about PrEP related to potential side effects, risk compensation (the idea that people will stop using condoms if PrEP becomes available), drug resistance, and cost. However, reviews of five major clinical trials involving about 6,000 participants by the Forum for Collaborative HIV Research shows no greater risk of side effects, no risk compensation, and no clinically significant development of drug resistance in participants.