Over the last few years, health departments, community based organizations, AIDS service organizations, and the Centers for Disease Control and Prevention (CDC) have been promoting PrEP, or Pre-Exposure Prophylaxis, to prevent new HIV infections. Numerous scientific studies support the optimism over PrEP’s ability to dramatically curb new HIV infections, with higher than 90% success rates when taken consistently.
Recently, however, a report about a Toronto man who became HIV-positive despite taking PrEP daily has caused some alarm, begging the question: should we continue to support PrEP as public policy?
PrEP is prescribed to individuals who are most vulnerable to HIV infection (e.g. men who have sex with men, people who inject drugs, those with multiple sex partners, and HIV-negative individuals with HIV-positive partners). The daily pill builds resistance against HIV. If an individual is exposed to the virus, this resistance helps prevent seroconverting (becoming HIV-positive). In some studies, taking the pill at least four times a week was enough to prevent seroconverting.
Until now, there had been no reports of any individual who is taking the pill as prescribed seroconverting. In fact, a San Francisco health insurance company announced that of the 657 patients on PrEP over two years, none contracted the virus.
Despite the strong evidence of PrEP’s effectiveness, unfortunately, drugs are rarely ever 100% effective.
What happened in this latest case?
HIV has many different strains. Some of these strains can become resistant to certain medications, including the “ingredients” of Truvada, the drug used as PrEP. Truvada is not a new drug. It has been in the market since 2004 as treatment for people living with HIV. It was approved in 2012 as a way of preventing HIV for those who are HIV-negative, or PrEP. The components of Truvada can be found in other HIV treatment regimens.
In this case, the HIV-negative individual engaged in receptive anal sex without condoms during the period in which he likely acquired the virus. Because the resistance was transmitted and did not develop after seroconverting, it is most likely that he acquired it from an HIV-positive individual who was on medication that included components of Truvada and became resistant to his treatment regimen. Thus, the HIV-negative individual’s own resistance was not able to prevent seroconversion because the strain was no longer responding to some of the ingredients in Truvada.
The easiest (but oversimplified) way to say this is that he acquired a Truvada-resistant strain of HIV, so Truvada as PrEP did not work.
What does this tell us?
It confirms what public health professionals have been saying over and over again (ad nauseam for some). PrEP is most effective when we combine it with other HIV prevention tools, namely condoms and treatment as prevention (using treatment to reduce the “amount” of HIV in a person’s system enough to prevent transmission to others).
PrEP has never been a blank check for us to completely eliminate or decrease other HIV and STD prevention mechanisms, especially not treatment as prevention.
All we know now is that along with not protecting against other STDs, PrEP – or at least not Truvada as PrEP – does not protect against all strains of HIV when the HIV-positive individual’s regimen is “failing.”
So does that mean we should give up on PrEP?
Absolutely not. PrEP must continue to be part of the equation—even if it’s not the only part. We still need education, routine testing, linkage to care, treatment as prevention and, yes, condoms.
Even considering this one event, PrEP is still very effective at preventing the spread of other strains of HIV. And this particular strain is very rare. Less than 1% of people living with HIV have this strain and if linked to care and on the right treatment, it is very unlikely that they will transmit the virus.
This case should stress the need for ongoing research on PrEP’s efficacy and drug-resistance. It should also stress the importance of not just treatment, but comprehensive care for people living with HIV so that if treatment is failing, providers can identify it early, find other ways to fight the virus, and make sure the individual not only has an undetectable viral load but is healthy.
Last week, CDC reported that if we reach our PrEP access goal, we could reduce new HIV infections by 70 percent by 2020.
Not taking PrEP does not protect against a Truvada-resistant strain of HIV. And condoms alone are only 70% effective at preventing HIV among gay men. With PrEP, at least the chances of acquiring other strains of HIV diminish.
We must use all the tools we can to end the epidemic. With the ability to prevent new HIV infections, regardless of strain, why wouldn’t we?