Scott Wiener, a member of the San Francisco Board of Supervisors, made anunusual public announcement on Wednesday: He takes Truvada, a daily antiviral pill, to greatly reduce his risk of contracting H.I.V.

Taking the pills is a practice known as pre-exposure prophylaxis, or PrEP, and some researchers believe it may reduce the risk of infection by 99 percent if patients take their medication daily as prescribed. Approved by the Food and Drug Administration in 2012, PrEP has increasingly been embraced by public health authorities and is one of three planks of Gov. Andrew Cuomo’s plan in New York to sharply cut new H.I.V. infections.

But it carries a stigma in some parts of the gay population, and Mr. Wiener appears to be the first public official to disclose that he’s personally on it.

“A much larger segment of gay men should be taking a close look at PrEP,” Mr. Wiener, who represents the same Castro-based district once held by Harvey Milk, said in an interview on Wednesday. “I hope that my being public about my use of PrEP can help people take a second look at it.”

According to data from the San Francisco Department of Public Health, there were 359 new H.I.V. infections in the city in 2013, 86 percent of them among men who have sex with men. Authorities including the World Health Organization and San Francisco’s health department say they believe that PrEP is a good strategy to cut new infections among gay men.

But PrEP has been slow to catch on. According to data from the city, there were fewer than 1,000 active prescriptions for Truvada as PrEP in San Francisco at the end of 2013.

On Thursday, the board will hold a hearing about increasing that number. David Campos, a supervisor who like Mr. Wiener is openly gay, will introduce a resolution directing the city’s health department to develop a plan by December that “addresses the educational and affordability issues” around Truvada. In particular, he and Mr. Wiener are focused on bringing down costs for people who would like to be on PrEP but can’t afford it.

(The Article By Joss Bro initial publixhed on New York Times)