A new recommendation from the World Health Organization about who should take drugs to prevent HIV is causing confusion and controversy nationwide.

Two years to the day after the U.S. Food and Drug Administration approved a once-daily pill to prevent HIV, the World Health Organization (WHO) has endorsed it as essential to prevent transmission of the virus in high-risk groups.

Although the approval of Truvada as PrEP, or pre-exposure prophylaxis, ignited a heated debate two years ago, the drug has since become widely accepted as safe and effective by doctors and HIV specialists. In fact, the U.S. Centers for Disease Control and Prevention recommended its approval for use in high-risk groups two months ago.

But the recent WHO endorsement has resulted in angry responses from some prevention specialists and commentators in the mainstream as well as the gay news media.

Headlines proclaimed that PrEP is recommended for all men who have sex with men. In fact, its use is suggested as an option for men who have sex with men, particularly those who may be at high risk for HIV transmission, as well as other groups who are or may be at high risk.

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Those at high risk often belong to “key populations,” the WHO reports, and have a higher than average likelihood of becoming infected. This is where battle lines need to be drawn, they argue, if the global community is to finally get a handle on the virus.

Key populations include men who have sex with men (who are 19 times more likely to contract HIV than the general population), female sex workers (14 times more likely), transgender women, and those who inject drugs (both 50 times more likely). These populations face marginalization in healthcare and even prosecution in some countries.

But not everyone in these groups, particularly gay men and transgender women, would be considered at-risk. It cannot be assumed that members of either group have frequent, or risky, sex.

Jim Pickett, director of prevention advocacy and gay men’s health at AIDS Foundation of Chicago, applauded the WHO recommendation, saying, “It’s about time.” But he also stressed that PrEP is not needed, or even proper, for everyone.

Men who never have anal sex probably don’t need PrEP, he said. Those who rarely have it and are always consistent and correct condom users may not need it either.

But those who frequently engage in anal sex and do not use condoms, especially receptive partners, should strongly consider PrEP. They also must be willing to take the pill every day, as directed. A prescription requires seeing the doctor regularly, usually every three months but sometimes once a month, for an HIV test and medications refills.

Dr. Otto Yang, a professor in the division of infectious diseases at the Geffen School of Medicine at the University of California, Los Angeles, said deciding whether to take PrEP needs to involve a risk-benefit analysis, like every decision in medicine. He said the medication does carry the risk of side effects, such as kidney failure, not to mention a financial burden.

“At one extreme is someone who has no exposures, or very rare exposures always using condoms, where PrEP shouldn’t be used,” he said. “On the other extreme is a person who has numerous unprotected exposures, who is otherwise reliable to take PrEP properly, where PrEP would have the most benefit.”

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There also is great debate over whether the use of PrEP could lead to a drug resistant strain of the virus. Resistant strains have appeared in people already infected with HIV who take PrEP not knowing they are infected. Although the HIV test required to get a prescription for Truvada is intended to prevent that, there can be a window between infection and actually testing positive for the virus.

Resistance can also occur if the medication is not taken regularly, and clinical trials have shown that many people take the medication erratically. Pickett said regular doctor visits for refills are intended to encourage patients to stick to the medication schedule. Refills are contingent on continuing to test negative for HIV, and patients taking PrEP need to be tested for HIV four times a year.

Headlines proclaiming that the WHO is mandating antiretroviral medications for all gay men incited outrage on news sites nationwide. On Monday, the WHO released a clarification on its recommendation, citing “incorrect headlines and reporting.”

The WHO stressed that PrEP should be taken into consideration as an additional method of preventing HIV infection, alongside the use of condoms.

Some HIV-positive activists decried the WHO recommendation, saying people around the world who are already infected with HIV need antiretroviral medication more than those at risk for infection. But the WHO emphasized that the intention is not to take medications from one group and give them to another, and that that is not what they are recommending.

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The PrEP recommendation is part of a much larger policy statement. The WHO released an almost 200-page report, “Consolidated guidelines on HIV prevention, diagnosis, treatment and care for key populations,” leading up to the 20th International AIDS Conference in Melbourne, Australia, which begins Sunday.

The report outlines specific interventions that are needed to reach those most at risk of contracting HIV. Such interventions were described as “critical” during an online press briefing last week in preparation for the conference. Officials speaking during the online presentation included Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases; Jennifer Kates, vice president and director of global health and HIV policy at the Kaiser Family Foundation, and Dr. Chris Beyrer, president-elect of the International AIDS Society.

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