Scientists have an exciting breakthrough in the fight against AIDS. A pill already used to treat HIV infection turns out to be a powerful weapon in protecting healthy gay men from catching the virus, a global study found.Daily doses of Truvada cut the risk of infection by 44 percent when given with condoms, counseling and other prevention services. Men who took their pills most faithfully had even more protection, up to 73 percent.
Researchers had feared the pills might give a false sense of security and make men less likely to use condoms or to limit their partners, but the opposite happened — risky sex declined.
The results are "a major advance" that can help curb the epidemic in gay men, said Dr. Kevin Fenton, AIDS prevention chief at the U.S. Centers for Disease Control and Prevention. But he warned they may not apply to people exposed to HIV through male-female sex, drug use or other ways. Studies in those groups are under way now.
"This is a great day in the fight against AIDS ... a major milestone," said a statment from Mitchell Warren, head of the AIDS Vaccine Advocacy Coalition, a nonprofit group that works on HIV prevention.
Because Truvada is already on the market, the CDC is rushing to develop guidelines for doctors using it for HIV prevention, and urged people to wait until those are ready.
"It's not time for gay and bisexual men to throw out their condoms," Fenton said. The pill "should never be seen as a first line of defense against HIV."
As a practical matter, price could limit use. The pills cost from $5,000 to $14,000 a year in the United States, but only 39 cents a day in some poor countries where they are sold in generic form.
Condoms still 'first line of defense' Whether insurers or government health programs should pay for them is one of the tough issues to be sorted out, and cost-effectiveness analyses should help, said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.
"This is an exciting finding," but it "is only one study in one specific study population," so its impact on others is unknown, Fauci said.
His institute sponsored the study with the Bill & Melinda Gates Foundation. Results were reported at a news conference Tuesday and published online by the New England Journal of Medicine.
The drug costs $1,000 a month in the United States but Gilead lets several Indian companies make cheap generic versions costing as little as 40 cents a dose for use in Africa and other developing nations.
Dr. Howard Jaffe, president of the Gilead Foundation, said the company was not planning any price changes.
Gay and bisexual men account for nearly half of the more than 1 million Americans living with HIV. Worldwide, more than 40 million people have the virus, and 7,500 new infections occur each day. Unlike in the U.S., only 5 to 10 percent of global cases involve sex between men.
"The condom is still the first line of defense," because it also prevents other sexually spread diseases and unwanted pregnancies, said the study leader, Dr. Robert M. Grant of the Gladstone Institutes, a private foundation affliated with the University of California, San Francisco.
But many men don't or won't use condoms all the time, so researchers have been testing other prevention tools.
AIDS drugs already are used to prevent infection in health care workers accidentally exposed to HIV, and in babies whose pregnant mothers are on the medication. Taking these drugs before exposure to the virus may keep it from taking hold, just as taking malaria pills in advance can prevent that disease when someone is bitten by an infected mosquito.
The strategy showed great promise in monkey studies using tenofovir (brand name Viread) and emtricitabine, or FTC (Emtriva), sold in combination as Truvada by California-based Gilead Sciences Inc.
The company donated Truvada for the study, which involved about 2,500 men at high risk of HIV infection in Peru, Ecuador, Brazil, South Africa, Thailand and the United States (San Francisco and Boston). The foreign sites were chosen because of high rates of HIV infection and diverse populations.
More than 40 percent of participants had taken money for sex at least once. At the start of the study, they had 18 partners on average; that dropped to around 6 by the end.
The men were given either Truvada or dummy pills. All had monthly visits to get HIV testing, more pills and counseling. Every six months, they were tested for other sexually spread diseases and treated as needed.
After a median followup of just over a year, there were 64 HIV infections among the 1,248 men on dummy pills, and only 36 among the 1,251 on Truvada.
Among men who took their pills at least half the time, determined through interviews and pill counts, the risk of infection fell by 50 percent. For those who took pills on 90 percent or more days, risk fell 73 percent. Tests of drug levels in the blood confirmed that more consistent pill-taking gave better protection.