For the first time in the 30-year battle against the HIV epidemic, a panel of experts has recommended that the Food and Drug Administration approve a drug to give to healthy people to protect against the infection.

The panel recommended Thursday that the agency approve the drug Truvada for preventing HIV in men who have sex with men, HIV-negative partners of HIV-postive people and “other individuals at risk for acquiring HIV through sexual activity.”

The FDA usually follows the advice of its advisory committees, which are made up of experts from outside the agency, although it does not have to. Its decision is expected by June 15.

FDA approval would mark a watershed moment in the fight against an epidemic that still causes 50,000 new infections a year in the United States. Worldwide, according to the United Nations Program on HIV/AIDS, 2.7 million new infections occur annually.

“I really think this provides for an amazing opportunity to turn the tide of the epidemic,” said Matthew V. Sharp, a patient advocate on the committee who voted for approval. “For somebody living with HIV for 23 years, I’m tired of seeing the ongoing infection rate.”

The committee wrestled all day with safety concerns, including fears that men taking the drug would see it as an excuse to stop using condoms, and worries that healthy people would not take the drug daily. The series of three votes, one for each category of user, was not unanimous, with dissents and abstentions ranging from two of the 22 committee members on the first vote to 10 on the third.

“I have significant safety concerns,” said committee member Lauren V. Wood of the National Cancer Institute, who voted against approval each time. Wood said Truvada can cause kidney problems. She also objected to the lack of U.S. women in the pivotal studies, which were largely conducted in Africa. “I want to make the committee aware that there is not a single African American female in any one of the studies put forward for approval. I think that’s unacceptable,” she said.

Truvada is already FDA-approved for the treatment of HIV. That means physicians are free to prescribe it “off label” for prevention; reports indicate that some already do. But a new FDA approval will free the company that makes the drug, Gilead Sciences, to market Truvada for prevention, too.

One local HIV/AIDS researcher said the “need for prevention is incredibly, incredibly important.” Richard Elion of the Whitman-Walker clinic in the District pointed to young men he counsels who continue having anal sex without condoms despite warnings to the contrary. “They need a new care plan, a new approach that works.”

The votes mark an “important moment,” said Jennifer Kates, an HIV/AIDS policy expert at the Kaiser Family Foundation. Still, she said, “there’s no single thing that’s going to change the trajectory of the epidemic.”

Studies presented to the FDA’s Antiviral Drugs Advisory Committee show that Truvada reduced the risk of acquiring HIV by 42 to 73 percent among men who have sex with men and among HIV-negative partners of people carrying the virus.

Those prevention rates would have been higher if all of the study participants had taken the pills daily as directed, Gilead representatives told the committee. Blood tests found that a large proportion of participants did not take the pills daily despite frequent visits with health-care providers.

Among participants who did take the pills daily, prevention rates were above 90 percent in three large international studies.

One Gilead study, of women in Kenya, South Africa and Tanzania, was stopped early because the drug did not prevent new infections. The researchers concluded that many participants were not taking the pills.

Andrew Cheng, Gilead senior vice president, told the committee that Truvada would be added to the “existing toolbox” of prevention methods, including education about safe sex, condom use and clean-needle programs.

Counseling high-risk individuals to practice safer sex has not reduced the number of new infections in the United States said Susan Buchbinder, director of HIV research at the San Francisco Health Department. For the past decade, that figure has remained stable, with three-quarters occurring in men.

Men who have sex with men account for most new infections. From 2007 to 2010, the proportion of new infections occurring in that group increased from 55 to 61 percent, according to the Centers for Disease Control and Prevention. Young black men who have sex with men are at the highest risk for contracting the virus. Blacks and Hispanics continue to be at higher risk than whites, according to the CDC.

Female condoms, another prevention option, have been credited with reducing the rate of new HIV infections in the District. Still, rates of HIV infection in Washington are the highest of any U.S. city; 3 percent of city residents are infected, a prevalence characterized as “epidemic” by the World Health Organization.

If approved for HIV prevention, Truvada could reduce the number of new infections in the District by about 1,000 over a decade, said Gilead consultant John Mellors, chief of the division of infectious diseases at the University of Pittsburgh, citing computer simulations run by researchers at Imperial College London.

During the public comment session Thursday, physicians, nurses and activists from the Los Angeles-based AIDS Healthcare Foundation expressed concerns that men at risk of contracting HIV would gain a false sense of security by taking Truvada. “In all of my conversations with gay men about [Truvada for prevention], the focus is on not having to use condoms anymore,” said Joey Terrill, an activist with the group.

Other advocates recounted stories of Truvada patients experiencing persistant diarrhea. Truvada can cause a “start-up syndrome” that includes diarrhea and abdominal and back pain, said Robert Grant of the University of California at San Francisco, who helped lead one of Gilead’s studies, although he said symptoms typically decline or disappear within four weeks.

Gilead representatives said their studies show no increase in risky sexual behavior among participants.

If the FDA approves Truvada for HIV prevention, Gilead would roll out education campaigns for patients and physicians and continue studies that monitor for serious adverse events, especially kidney damage and decreases in bone density, company officials told the committee. Gilead would also recommend that patients are confirmed as HIV-negative before being given the drug; if they are HIV-positive, taking Truvada could lead to drug-resistant strains of the virus.

For more than an hour, the committee wrestled with how the FDA might ensure that new patients are indeed HIV-negative and whether that responsibility should rest with physicians or pharmacists. The panel reached no conclusion.

T ruvada has been a blockbuster for Gilead, with sales of $758 million in the first quarter of 2012. Truvada was approved by the FDA in 2004 to treat HIV in combination with other drugs. Truvada is a combination of two drugs, Viread and Emtriva, that interfere with HIV’s ability to reproduce.

In the United States, about 275,000 men who have unprotected sex with men and 140,000 individuals whose partners have HIV are at high risk of contracting the virus, according to the CDC.

Gaining widespread insurance coverage of Truvada for HIV prevention could be a hurdle for Gilead: There is no diagnostic code — typically needed for reimbursement — for simply being at risk for HIV. The drug costs about $11,000 a year.