Non-Daily PrEP Strategy is Finally Being Taken Seriously

Since July 2012, the U.S. Food and Drug Administration has encouraged the daily use of Truvada in the HIV prevention strategy known as pre-exposure prophylaxis, or PrEP. Earlier this year, it added the drug Descovy as another daily PrEP option. But newer strategies are emerging for people who struggle with adherence to daily PrEP.

Experts still recommend that some high-risk populations take the medication daily to ensure protection. For example, some studies suggest that for trans women, feminizing hormones may quicken the filtering of Truvada and Descovy out of their bodies, so they may need to maintain daily adherence to keep an effective dose in their systems. But some lower-risk communities may soon have new options in practicing PrEP.

Some San Francisco health experts are embracing a new dosing regimen that doesn't require indefinite day-after-day usage of the drug, according to The Bay Area Reporter.

Dubbed "PrEP 2-1-1" (for the number of pills a person must take over the course of a few days), this PrEP-on-demand option is especially designed for those who are only intermittently sexually active. It requires a person to take two pills at least two hours--but preferably 24 hours--prior to engaging in sex. Then another pill must be taken 24 hours later and every 24 hours after that during the period they are sexually active, with a final pill taken 48 hours after the last sexual encounter.

The 2-1-1 strategy could be useful for those who only engage in sexual encounters intermittently, who may be engaging in a one-time encounter with a higher-risk partner, or who want to hook up while on vacation.

"We think it's going to bring a whole lot of people to PrEP who previously did not feel like PrEP was for them," Dr. Chris Hall, former vice president of medical affairs at the San Francisco AIDS Foundation, told the Reporter.

The foundation is currently operating a pilot study of PrEP 2-1-1 at Strut, its health center for men in the Castro, San Francisco's gay neighborhood. The study is seen as a first step in proving to the FDA that the PrEP 2-1-1 strategy deserves federal approval.

The International AIDS Society-USA has already endorsed PrEP 2-1-1, as have health officials in France, the United Kingdom, Canada, and Australia. As there's no coordinated tracking system in the U.S., it's difficult to estimate the number of people utilizing Truvada or Descovy as PrEP, but health officials estimate it's between 100,000 and 200,000 people. The need for indefinite adherence has been one thing that's kept that number from increasing--something that could change if people only needed to take the medication essentially before and after engaging in sex, rather than daily.

"So far we've [only] ever really emphasized the use of PrEP every day to keep HIV away, but 2-1-1 dosing is a different way," rhymed PrEP expert Dr. Robert Grant of the UCSF-Gladstone Center for AIDS Research at a November 2019 Strut forum, in an apparent effort at a memorable mnemonic phrase. "2-1-1 dosing is only when you're having sex. Two pills before sex, one pill the day after sex, and a fourth pill two days after sex. It is used when you're having sex, and if you're not having sex then you don't take PrEP."

"Both daily dosing and 2-1-1 dosing are highly effective," added Grant, who was the lead investigator in the iPrEx Study, which demonstrated Truvada's effectiveness in preventing HIV transmission. "In the trials of 2-1-1 dosing we did not see anyone become HIV-positive if they're actually taking 2-1-1."