On July 3, 1981, this newspaper wrote about a “rare cancer” killing gay men in New York and California. Though few knew it, what followed would be a generation-defining battle: for attention, for legitimacy, for our very lives. Today, after 37 years, we finally have a proven pathway to ending the AIDS epidemic in this country.

The only catch? Poor policy and pharmaceutical price-gouging have blocked the way, making critical drugs a luxury rather than an imperative.

The solution comes in a pill: Taken daily, Truvada, the brand name for a type of pre-exposure prophylaxis, or PrEP, is up to 99 percent effective at preventing H.I.V. infection. Used as directed, it’s one of the most effective methods of preventing a viral infection ever discovered, as good as the polio vaccine, the miracle of modern medicine. When you combine PrEP’s effectiveness with the discovery that people living with H.I.V. cannot transmit the virus to others once they become undetectable, we could be on the verge of a swift end to the epidemic.

Truvada was approved by the Food and Drug Administration in 2012. But over six years later, the United States is failing miserably in expanding its use. Less than 10 percent of the 1.2 million Americans who might benefit from PrEP are actually getting it. The major reason is quite clear: pricing. With a list price over $20,000 a year, Truvada, the only PrEP drug available in the United States, is simply too expensive to become the public health tool it should be.