MELBOURNE, Australia — It took universal health care, political will and a health campaign designed to terrify the public, but nearly four decades into the H.I.V. crisis, Australian researchers say the country is on a path toward making transmissions of the virus vanishingly rare.

The fight is not yet won, the experts caution, and the last stretch of disease eradication efforts is often the toughest. But in the past five years, the number of new infections with the virus has dropped by almost a quarter in Australia, with higher declines among gay and bisexual men, according to a report released last week by the Kirby Institute, an infectious disease research center in the state of New South Wales.

In 2018, just 835 H.I.V. diagnoses were recorded nationally. At their peak, in 1987, there were 2,412.

The most recent advance in Australia’s battle against the virus, which is seen as a model around the world, is the rapid adoption of a drug regimen known as PrEP. Under the regimen, patients typically take a daily pill, which — even without the use of condoms — is close to 100 percent effective at preventing contraction of H.I.V., experts say.

In Australia, more than 40 percent of gay men considered to be most at risk of infection are on PrEP, according to the Kirby Institute. Adoption rates are lower in the United States. While the Centers for Disease Control and Prevention has said that more than 1.1 million Americans need PrEP, one group that tracks data on the regimen says that only about 270,000 are on it. The C.D.C. is expected to release new figures on Thursday about the use and awareness of the regimen in the United States.

“Provided we don’t take our foot off the pedal, we stand a chance of eliminating H.I.V. by 2030” in Australia, said Andrew Grulich, an author of the Kirby Institute report and a professor of epidemiology at the University of New South Wales.

Truvada, which is used for H.I.V. treatment and PrEP — the abbreviation stands for pre-exposure prophylaxis — was formally added as a preventive medication to the list of pharmaceuticals available at subsidized rates under Australia’s universal health care program in April 2018.

Since then, any permanent resident or citizen of Australia has been able to get the pill, or its generic alternative, by obtaining a prescription from a doctor and purchasing it from a pharmacy. For these people, it usually costs about 40 Australian dollars, or $28, per month. Read more via New York Times