His doctor wasn’t so sure. “Well, what do you need it for?” she probed, before offering to “look into it.” Williams sensed that she was trying to change the subject. “I don’t understand what the hold up is,” Williams told me two months after his initial appointment requesting the medication.

As far as he could tell, his doctor seemed unclear about best practices for prescribing PrE, telling Williams that she needed to learn more about it herself. Williams had completed all of the necessary lab work along with a full physical, but he still hadn’t gotten access to the drug. “I definitely want to continue to have sex, but I also want to keep my body safe,” he told me.

In theory, it has become miraculously easy to avoid getting HIV in the United States today. Is PrEP right for me? What is PrEP?

PrEP is a preventative medicine that greatly reduces your risk of contracting HIV. It comes in the form of a daily pill or a bimonthly injection. Who is PrEP for?

PrEP is for anyone at risk of HIV, including those with multiple sexual partners, a recent history of sexually transmitted infections, inconsistent condom use, or a history of drug use. How does it work? Getting on PrEP requires a negative HIV test — plus a few other screenings — and a health care provider’s prescription.

How much does it cost? Nothing for most people. Most insurance providers cover PrEP. There are also assistance options available for uninsured patients.

How to learn more: You can find a nearby PrEP provider through the HIV Services Locator, the CDC’s PrEP Locator, or AIDSVu. You can also get a prescription online through providers like MISTR or state-run telePrEP programs. For people who are HIV negative, a once-daily PrEP pill can prevent infection during sex with someone who is HIV positive no less than 99 percent of the time.

At the same time, most of the 1.2 million Americans living with HIV follow an anti-retroviral therapy regimen that is so effective that it can make their HIV non-transmissible. These treatments are both a marvel of modern medicine and a living tribute to the more than 700,000 Americans who have lost their lives to HIV since the first reported cases appeared in 1981. Getting on PrEP, which was approved by the FDA in 2012, should be about as easy as getting on birth control, another daily pill prescribed for sexual health.

In both cases, side effects are minimal and rare, and the costs are covered by most insurance plans. But despite all that, PrEP remains exasperatingly out of reach for hundreds of thousands of people in the US who need it. Most Americans — about 60 percent — don’t know about PrEP in the first place.

Even if they do know enough — and have the health coverage they need — to ask a doctor about it, less than half of physicians feel knowledgeable enough to prescribe PrEP, as Williams found. And other people still often struggle with stigma from their communities and even from their health care providers. As a result, only about one-third of people at risk of HIV in the US currently take PrEP.

Worse yet, those who are the most likely to benefit from its protection are often the least likely to be on the medication. Among people at risk of HIV, Black and Latino bisexual and gay men, women, and Southerners consistently take PrEP at much lower levels than the rest of the population, which may account for the troubling increase in new HIV infections over the past decade in some areas in the US. “We’ve had a dramatic drop in new infections over the past 15 years, but we’ve plateaued, and we’ve plateaued among those same vulnerable populations,” said Carl Baloney Jr., president of AIDSUnited.

People like Brenton Williams can do everything right, he said, and yet, they still get lost in the cracks of this country’s warped health system, either because they lack health insurance, or because their providers don’t know about PrEP well enough to prescribe it. The gaps in PrEP coverage may soon get even wider, because the Trump administration has slashed hundreds of millions of dollars in grants earmarked for PrEP outreach and HIV prevention. It is a maddening time to be an HIV advocate in the United States.

After decades of getting to the point where an America free of HIV seemed in sight, the country feels on the verge of a tragic reversal. And the availability of PrEP is one of the most important factors in deciding what comes next. “This is a disease that, with some strong policy support and politi