HIV Prevention Breakthrough

There was big news today in the world of HIV prevention. A large randomized controlled trial demonstrated that a new, injectable drug made people much less likely to contract HIV. The drug, called CAB, built on the last major breakthrough in HIV prevention: Truvada.

Truvada is a once-daily antiviral pill taken as pre-exposure prophylaxis, or PrEP. My understanding – I’m not a biologist – is that the drugs in Truvada were originally used to treat HIV by making it more difficult for the virus to replicate. If you give it to people who aren’t infected yet, it gives them a good chance of staying uninfected even if they’re exposed to the virus. It’s extremely effective. This large RCT found that giving it to cisgender men or transgender women who have sex with men reduced their HIV risk by 44%. These two RCT’s enrolled heterosexual couples where one person had HIV and the other didn’t. The couples were randomly assigned to a control group that received standard HIV prevention services or a treatment group that received standard services plus Truvada.  The first study found a 75% reduction in HIV risk and the second found a 62% reduction.

This 2015 New York Times profile gives a glowing review of San Francisco’s approach to preventing and treating HIV, which heavily relies on Truvada among other tools. (I’d read the article years ago, but had glossed over the name of the first expert they quote, the one-and-only Dr. Anthony S. Fauci.) The article is a great read, a paean to evidence based public health policy before the days of coronavirus.

The new drug is an injectable form of PrEP taken every two months. The study that came out today, like the first one above for Truvada, treated cisgender men and transgender women who have sex with men. People taking the new injections had a 69% reduction in HIV risk compared to the Truvada group. Another trial that’s still running is measuring the effect of the new drug in cisgender women. These results are another huge step on the path to ending the HIV epidemic.

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