An antiviral pill taken daily by thousands of men across Sydney and other parts of Australia led to a globally unprecedented reduction in new HIV cases, showing that a targeted, preventative approach may accelerate progress on ending the AIDS epidemic.

New cases of HIV among gay and bisexual men fell by almost a third to the lowest on record, according to the world’s first study to measure the impact of Gilead Sciences Inc.’s Truvada pill on reducing the AIDS-causing virus in a large population. The results, published Thursday in the Lancet HIV medical journal, may pave the way for other states and countries to stop transmission of the virus with the use of a treatment called pre-exposure prophylaxis (PrEP).

“The speed of the decline we’ve seen in new HIV infections in gay and bisexual men is a world first,” said study leader Andrew Grulich, head of HIV epidemiology and prevention at the Kirby Institute of the University of New South Wales. “These numbers are the lowest on record since HIV surveillance began in 1985.”

Progress against AIDS over the past 15 years has inspired a commitment by U.N. member states to end the epidemic by 2030. The number of people newly infected with HIV fell to 1.8 million worldwide in 2017, from more than 3 million a year through most of the 1990s. While the study results can’t be generalized to indicate similar efficacy in heterosexual populations, they do demonstrate that PrEP is “highly cost-effective” in certain high-risk groups, Grulich said in a phone interview.

New HIV infections occurred in 102 gay and bisexual men in the state of New South Wales in the first year after the study began, compared with 149 infections in the 12 months prior.

“While we’ve known for at least three or four years now of individual-level efficacy of PrEP, there has been some reticence around the world by policymakers to properly fund the roll out of PrEP because the population impact hasn’t been shown — and that’s what we set out to do,” Grulich said.

There were about 180,000 people in the U.S. taking Truvada for PrEP at the end of June, Robin L. Washington, Gilead’s chief financial officer, said on a conference call in July.

The blue, oval-shaped pill is a fixed-dose combination of the drugs tenofovir, disoproxil and emtricitabine. Generic versions of Truvada made by Mylan NV, Cipla Ltd. and Teva Pharmaceutical Industries Ltd. have made the medication available more cheaply.

“We see the nice steady growth of Truvada for the use of PrEP,” Gilead Chief Executive Officer John F. Milligan told the Morgan Stanley Global Health Care Conference last month. Areas of the U.S. with the highest uptake of PrEP had achieved some of the best reductions in HIV infections, he said.

“I’m more confident now that the policymakers are being very innovative in thinking about how to increase access to PrEP,” Milligan said. “So we’ll be working on a number of things in the coming year that could really increase the number of patients on PrEP and could be very good for preventing the infection, and of course good for our business as well.”

KEYWORDS medicine, health, HIV, pharmaceuticals