Enough people are taking the HIV-prevention drug to finally lower infection rates around the world

In major cities across the global, widespread PrEP use is dramatically reducing new HIV cases.
In major cities across the global, widespread PrEP use is dramatically reducing new HIV cases.
Image: Amanda Baeza for Quartz
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Six years after the Food and Drug Administration approved a revolutionary HIV prevention pill known as PrEP, public health officials in select US cities have finally begun to conclude that it is likely taking a bite out of local HIV infection rates.

PrEP, short for pre-exposure prophylaxis, is akin to a birth control pill—only one that prevents HIV instead of pregnancy. The powder-blue tablet, which goes by the brand name Truvada, contains a pair of antiretroviral medications that were first approved to treat HIV in 2004. Truvada works by blocking HIV from replicating in the immune cells the virus infects—and, when used daily as PrEP—from establishing a permanent infection if someone is exposed to the virus. In other words, PrEP harnesses the power of a medication designed to control the virus in people living with HIV to prevent those without the virus from contracting it in the first place. Haven’t heard of PrEP? You like will soon thanks to its first-ever television ad campaign that will debut this month from Truvada’s manufacturer, Gilead Sciences.

When HIV-negative men take Truvada daily, they lower their risk of contracting the virus through sex with men by an estimated 99% or more. This fact holds considerable promise considering that gay and bisexual men made up about 70% of the estimated 38,500 new HIV cases in the United States in 2015—the most recent year for which such a figure from the Centers for Disease Control and Prevention is available. Owing to a less robust pool of related data regarding vaginal intercourse, scientists have a foggier picture of how well Truvada prevents HIV transmission through this route; still, studies indicate that PrEP is at least 90% effective among women.

PrEP, which has a wholesale cost of over $1,000 per month, is generally covered by insurance, including Medicaid. Gilead Sciences will cover up to $4,800 per year in out-of-pocket expenses related to filling the prescription. Many people—at least for now—pay nothing for their pill bottles.

Antiretroviral pills Truvada. (Justin Sullivan/Getty Images)
Antiretroviral pills Truvada. (Justin Sullivan/Getty Images)

The drug’s game-changing potential notwithstanding, PrEP got off to a surprisingly inauspicious start. Probably only about 10,000 people tried PrEP during the first year or so after its approval in July 2012. Then, in late 2013, a slew of media reports began to question why so few people were taking PrEP. By early 2014, PrEP’s use began to pick up—and then soar. According to Gilead, an estimated 167,000 were on PrEP in the US as of early 2018. That’s up from 153,000 during the last quarter of 2017 and 125,000 during the first quarter of that year. Meanwhile, across the globe an estimated 300,000 people are now using PrEP—and the medication has recently been approved for use by teenagers.

Study after study has found consistent demographic patterns in the US behind these figures: In short, PrEP users are predominantly white, gay and bisexual men over 25. (A modest proportion of users are women, although this population isn’t expanding too rapidly.)

What such data reveals, sadly is that among gay and bi men, the folks who would most benefit from PrEP are actually those using it the least—gay and bi African Americans, who account for one in four new infections in the United States. Indeed, researchers have found that perhaps no more than 10% of PrEP users are black. What’s more, Latino gay and bi men—whose increasing HIV rate has alarmed and perplexed public health experts—apparently use PrEP only a bit more commonly than their African-American counterparts.

Advertising on the subway in New York on Sunday, January 3, 2016 promotes the use of HIV testing, prophylactic drugs and condoms to combat the spread of AIDS and sexually transmitted infections. (Photo by Richard Levine/Corbis via Getty Images)
Advertising on the subway in New York on Sunday, January 3, 2016 promotes the use of HIV testing, prophylactic drugs and condoms to combat the spread of AIDS and sexually transmitted infections. (Photo by Richard Levine/Corbis via Getty Images)

PrEP’s introduction has certainly raised various concerns—most notably regarding the question of whether Truvada will accelerate the long-declining rate of condom usage among gay and bi men. A recent review of numerous PrEP studies conducted from 2014 to 2017 found that starting Truvada for HIV prevention was associated in an uptick in sexually transmitted infection (STI) diagnoses, which suggests that men were indeed forgoing condoms more often during the period immediately following going on PrEP. That said, a CDC modeling study recently projected that even if these men’s condom adherence plummets, their use of PrEP may actually help lower the overall STI rate in their communities. That’s because PrEP users typically undergo STI screening every three to six months—which can identify and treat infections promptly.

On the side-effect front, PrEP often gets a bad rap. One study found its safety, at least in the short-to-medium term, was favorable to aspirin. Truvada is associated with small, initial reductions in bone mineral density and kidney function. However, studies have indicated that both shifts are reversible after individuals stop taking PrEP, and there have been no reports of Truvada leading to an actual bone fracture or kidney disease among HIV-negative individuals using it for prevention.

How do we know if PrEP is driving down HIV?

The strongest evidence to date that PrEP works on a grand scale comes from a recent Australian study. Starting in early 2016, researchers in New South Wales provided PrEP to an enthusiastic surge of 7,600 gay and bi men living in the state. After its first year, the study saw an astonishing 32% decline in diagnoses of recently contracted HIV among all gay and bi men in New South Wales.

This demographic’s HIV diagnosis rate had been stable during the preceding years—a fact that contributed to the study authors’ conclusion that PrEP was the key variable propelling this plunge in HIV transmissions.

As for the US HIV epidemic, local governments in New York City, San Francisco, and Seattle have been particularly proactive in promoting PrEP (and collecting data about its use), and now seem to be reaping the benefits.

In New York City, there was a nearly 15% drop between 2015 and 2016 in new HIV diagnoses among gay and bi men, to just over 1,200 cases—the steepest one-year drop on record.

“The only major change we saw [during this period] was explosive increases in the uptake of PrEP” among gay and bi men, said Demetre Daskalakis, deputy commissioner of the city’s Division of Disease Control. “With some of our data indicating that nearly 30% of these men currently use PrEP. It seems clear from our data and the reports from other jurisdictions that PrEP is an effective strategy to eliminate new HIV transmissions and could be a scalable public health intervention.”

In other words, PrEP works, and is certainly poised to benefit other populations at high risk for HIV in cities across the country.

San Francisco’s overall HIV diagnosis rate has been on a freefall in recent years—dropping from 532 in 2007 to 223 in 2016, including a 50% reduction after 2012. Susan Buchbinder, a leader of the HIV team at the San Francisco Department of Public Health, said that “PrEP is likely helping to drive down new infections” in the Bay Area city. An estimated 20,000 people take Truvada for prevention there—representing perhaps half of those residents who are at significant risk of HIV.

The HIV diagnosis rate in King County, which includes Seattle, has charted its own healthy HIV decline of late, with local public health officials also coming to the conclusion that the local popularity of PrEP is apparently contributing to this shift.

All these data strongly suggests that there’s a sea change benefitting white gay and bi men in particular who live in those major urban areas where PrEP has woven its way into the fabric of gay sex. For them, HIV transmission is becoming increasingly uncommon, and may soon collapse.

Meanwhile, their black and Latino counterparts, especially those in the US South—the new hotbed of the US epidemic, where PrEP happens to lag behind other regions—are essentially being left behind.

This story is part of our series on Global Pride.