By Robert Preidt
Researchers followed 3,700 gay men who were given what's known as pre-exposure prophylaxis (PrEP) under a program in New South Wales, Australia. The regimen generally involves taking a daily pill.
Most followed the regimen. Among those men, the incidence of HIV infection was less than 1 in 2,000 per year with PrEP, compared with an expected incidence of 2 per 100 per year or more without PrEP.
The number of newly diagnosed HIV infections fell from 295 cases in the year before the PrEP program rollout to 221 cases the year after. That was the fewest since 1985, when collection of HIV data began, the researchers said.
The study was published Oct. 17 in The Lancet HIV journal.
"PrEP is a highly effective preventative approach when implemented alongside high levels of HIV testing and treatment," lead author Dr. Andrew Grulich said in a journal news release.
Grulich is head of the Epidemiology and Prevention Program at the University of New South Wales Sydney.
"Rollout should be prioritized as a crucial component of HIV prevention in epidemics predominantly affecting men who have sex with men," he added.
A number of other countries have approved PrEP. It was approved in 2012 in the United States, where it was estimated that 492,000 men would benefit. After a slow start, by late 2016, about 83,700 U.S. men had begun PrEP, according to the researchers.
Sheena McCormack, a professor of clinical epidemiology at MRC Clinical Trials Unit at University College London, wrote an accompanying editorial.
In it, McCormack said the study provides "robust evidence for the added value of PrEP at the population level, as well as endorsing the biological efficacy [effectiveness] in individuals who use PrEP consistently during periods of possible exposure to HIV."