AIDS drugs prevent sexual transmission of HIV in gay men

LONDON, May 2 (Reuters) - A European study of nearly 1,000 gay male couples who had sex without condoms – where one partner had HIV and was taking antiretroviral drugs to suppress it - has found the treatment can prevent sexual transmission of the virus.

After eight years of follow-up of the so-called serodifferent couples, the study found no cases at all of HIV transmission within couples.

The study proves, the researchers said, that using antiretroviral therapy to suppress the AIDS virus to undetectable levels also means it cannot be passed on via sex, the researchers said.

"Our findings provide conclusive evidence for gay men that the risk of HIV transmission with suppressive ART is zero," said Alison Rodger, a professor at University College London who co-led the research.

She said this "powerful message" could help end the HIV pandemic by preventing the virus' transmission in high-risk populations. In this study alone, for example, the researchers estimate that the suppressive antiretrovial treatment prevented around 472 HIV transmissions during the eight years.

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Members of the Christopher Street Liberation Day Committee (CSLDC) carry a banner through a street in New York City, USA, June 1983. (Photo by Barbara Alper/Getty Images)
CANADA - JANUARY 01: Guards fear AIDS: Prison guards argue they need better protection against inmates with AIDS or related diseases. (Photo by Boris Spremo/Toronto Star via Getty Images)
UNITED STATES - AUGUST 18: MAYOR KOCH SHAKES HANDS WITH HOSPITALIZED AIDS VICTIM, Secretary of Health and Human Services Margaret Heckler Joins Mayor Koch at bedside of AIDS victim Peter Justice., (Photo by Harry Hamburg/NY Daily News Archive via Getty Images)
CANADA - JUNE 09: Probing deadly illness: Dr. Jay Keystone; a member of a team trying to get money to study the disease AIDS; says it's claiming relatively few victims but appears to be spreading. (Photo by Bob Olsen/Toronto Star via Getty Images)
An AIDS protection pack from the Rajneesh Medical Corporation containing latex gloves, a condom and HR lubricating jelly, Oregon, USA, circa 1984. This image was taken in the hotel room of cult leader Bhagwan Shree Rajneesh, aka Osho. (Photo by Kypros/Getty Images)
PARIS - APRIL 4: (From left to right) Luc Montagnier, Jean-Claude Chermann and Françoise Barre-Sinoussi, the three Franch scientists who helped to discover the causes of AIDS (Acquired Immune Deficiency syndrome), in Pasteur Institute of Paris on April 4, 1984, the day after the announcement by American Health minister. The new virus discovered by these scientists is called LAV (Lumphadenopathy-associated virus). Francoise Barre-Sinoussi and Luc Montagnier shared the Nobel Medicine Prize on October 6, 2008 for their discovery of the HIV virus, along with a German scientist for his groundbreaking research into cervical cancer. (Photo by Michel Clement/AFP/Getty Images)
UNITED KINGDOM - JANUARY 12: Made by Wellcome, 3'-azido-3'-deoxythymidine (AZT), was also known as zidovudine in the UK. AZT is a drug used to treat HIV, the virus which an lead to AIDS. (Photo by SSPL/Getty Images)
A patient with AIDS, at St Mary's Hospital, Paddington, 1985. (Photo by Michael Ward/Getty Images)
CANADA - DECEMBER 11: Members of the AIDS Committee of Toronto meet at their headquarters (Photo by Ron Bull/Toronto Star via Getty Images)
Aids Victim Ryan White, 14, banned from Kokomo, Ind., high school because of disease, and actress Mary Beth Hurt. (Photo By: Richard Corkery/NY Daily News via Getty Images)
Members of the People With AIDS (PWA) movement carry a banner during the Gay Pride parade in New York City, USA, June 1986. (Photo by Barbara Alper/Getty Images)
Aids patient Paul Keenan is assisted by volunteer Lorna Kelly at St. Clare's Hospital. (Photo By: /NY Daily News via Getty Images)
AIDS VICTIM Priscilla Diaz is reunited with children Jasmin, 7, and twins Saul and Christian, 5, at her Bronx home. A fourth child, Milton, 15, is due home shortly. Weak and in pain, Diaz, 36, had to send her four children to live with relatives in Miami and Puerto Rico last December. Loneliness only worsened her suffering. But a caring Dr. Carol Harris and Nurse Marge Fenn of the Bronx Municipal Hospital Center helped arrange the tearful reunion yesterday. Hospital officials said that Diaz contracted AIDS from her husband, a drug abuser who died of the disease last April. (Photo By: Jim Hughes/NY Daily News via Getty Images)
A Buddhist monk tends to an AIDS patient at the Wat Phra Bat Nam Phu buddhist temple in Lop Buri which provides care for those dying with the disease, Thailand, circa 1987. (Photo by Robert Nickelsberg/Getty Images)
Buddhist monks attend the funeral ceremony of a deceased AIDS patient at the Wat Phra Bat Nam Phu buddhist temple in Lop Buri which provides care for those dying with the disease, Thailand, circa 1987. (Photo by Robert Nickelsberg/Getty Images)
President Ronald Reagan visits National Institutes of Health, where he holds a 14-month old baby with AIDS, Bethesda, Maryland, 1987. (Photo by Pete Souza/PhotoQuest/Getty Images)
March 10, 1987 Washington Post photo by Frank Johnston Location: Harlem Hospital, New York City CAPTION: A young brother and sister, who can not be identified, are among the many AIDS victims at the Harlem Hospital in New York. Their mother abandoned them after birth, never to return.
March 18, 1987 Washington Post photo by Frank Johnston LOCATION: The Harlem Hospital, New York City CAPTION: A child is tethered to a door knob in the AIDS pediatric ward.
Each morning with his breakfast Michael May opens a bottle of a drug called AL-721 and spreads it like margarine ona piece of bread. It's unbelievably simple, the stuff is extracted from egg yolks. A year ago the 40-year-old chorus and orchestra leader was too weak to get ou tof a wheelchair, a fungus had spread through his arms and legs, he had pneumonia and he knew he was going to die of AIDS. Now he is an AIDS patient with a rare story (Photo By: Gene Kappock/NY Daily News via Getty Images)
If You're Dabbling in Drugs, 1989. American Public health poster for AIDS. (Photo by: Universal History Archive/UIG via Getty Images)
CANADA - JUNE 28: Poster campaign: Posters on TTC shelters are part of a campaign to increase awareness about AIDS. Ontarians believe fear of the disease will lead to longer marriages. (Photo by Boris Spremo/Toronto Star via Getty Images)
December 23, 1987 Washington Post photo by Fred Sweets Location: 1336 Harvard St., NW. CAPTION: Alex Compagnet, president of Salud, a D.C. health organization, teaches a class on AIDS designed for Hispanics.
Members of Act Up = Aids Coalition to Unleash Power hold up signs and placards during the Gay and Lesbian Pride march, New York, New York, June 26, 1988. (Photo by Eugene Gordon/The New York Historical Society/Getty Images)
CANADA - JUNE 28: Ron Lentz: Nurse with AIDS returns to work at Toronto Western Hospital tomorrow. (Photo by Ron Bull/Toronto Star via Getty Images)
WASHINGTON - OCTOBER 8: Spectators linger to look at individual handmade panels of the 8,288 that make up the AIDS quilt in Washington, D.C. on Oct. 8, 1988, its final stop in the year-long national tour. Each panels honors a victim of the disease. The quilt has grown fivefold while traveling to more than 20 cities. (Janet Knott/The Boston Globe via Getty Images)
CANADA - OCTOBER 18: Preventing AIDS: Bleachman shows how drug users can sterilize needles. (Photo by Doug Griffin/Toronto Star via Getty Images)
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LaToya Jackson reaches out to a patient in pediatric ward of Bronx-Lebanon Hospital yesterday. She served breakfast to children in the huge South Bronx hospital and announced that she's planning a 1990 concert to benefit an AIDS hospice for children at Bronx-Lebanon. It was her last stop here before taking off for Europe to finish work on a new album. (Photo By: Jack Smith/NY Daily News via Getty Images)
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AIDS medicine smuggler Francisco Ortega, of Santa Ana, has been taking thousands of dollars worth of donated recycled AIDS medicine from Orange County and Los Angeles to Tijuana, Mexico to AIDS patients who cannot afford the lifeÂsustaining drugs. AIDS clinic doctors and managers credit the 'mercy smugglers' with helping improve the healthÂand brightening the livesÂof hundreds of poor patients who either cannot afford or don't have access to the most advanced medication. Here, Ortega drops off the medicine at an AIDS outreach center in San Diego, which will then be transported across the border to BiÂNational AIDS Advocacy Project and Casa Hogar Las Memorias in Tijuana. (Photo by Al Schaben/Los Angeles Times via Getty Images)
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The study, published in the Lancet medical journal on Thursday, assessed the risk of HIV transmission between serodifferent gay male couples - where one partner is HIV-positive and one is HIV-negative - who do not use condoms.

Its findings add to an earlier phase of the study which looked at HIV transmission risk for serodifferent heterosexual couples in the same circumstances. It also found zero risk.

While 15 of the men among the 972 gay couples in this phase did become infected with HIV during the eight years of follow-up, genetic testing showed their infections were with strains of HIV acquired from another sexual partner.

Since the start of the AIDS epidemic in the 1980s, more than 77 million people have become infected with HIV. Almost half of them - 35.4 million - have died of AIDS.

Global health experts say the fight against HIV is at a precarious point, with the annual number of AIDS deaths falling and the number of people getting antiretroviral treatment rising, but the number of new infections is stubbornly high at around 1.8 million new cases a year worldwide.

Rachel Baggaley, the World Health Organization's coordinator for HIV prevention and testing, said this latest study "adds to the clear and consistent evidence" that HIV transmission to sexual partners does not occur when someone with HIV is on antiretroviral therapy (ART) and their virus is suppressed.

"Increasing access to HIV testing (and) ART ... remains critical for individuals and is central to the HIV public health response," she said. (Editing by William Maclean and Janet Lawrence)

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