Last week, the World Health Organization took a seemingly bold step by suggesting that all men who have sex with men should consider pre-exposure prophylaxis (PrEP) as a means of preventing HIV. Headlines appeared almost instantly questioning why the organization would want all gay men to be on PrEP when not all men who have sex with men are at risk of HIV. The organization quickly clarified that this was not the intent of its announcement. Instead, the group wants all men who have sex with men to work with their health-care providers to assess their personal risk and determine whether this option is right for them.

This clarification brings the World Health Organization (WHO) guidelines in line with those released by the Centers for Disease Control and Prevention (CDC) in May. While not nearly as provocative as initial reports suggested, the release of these guidelines indicates growing support for PrEP and a new global focus on groups that remain disproportionally affected by the HIV epidemic.

PrEP is a combination of two anti-retroviral drugs—tenofovir and emtricitabine—used to treat individuals who have HIV. When used daily in HIV-negative individuals these drugs have been shown to prevent transmission of the virus.

In the United States, PrEP is given using one pill that contains both medications, sold under the brand name Truvada. Truvada was approved by the Food and Drug Administration for prevention purposes in 2011. Studies have found that it is very effective. One study of men who have sex with men, for example, found that those who were given PrEP were 44 percent less likely to contract HIV than those who weren’t. More importantly, those who remembered to take their medication every day or almost every day saw a reduction in risk of 73 percent or more (some up to 92 percent). Studies of HIV-discordant, heterosexual couples (couples in which one partner has HIV and the other does not) found that PrEP reduced the risk of the uninfected partner becoming infected by 75 percent, or as much of 90 percent among those who took the pill every day or almost every day.

There has been mixed reaction about PrEP among public health professionals since the drug was introduced. Many are excited about this new addition to the HIV-prevention arsenal, which has been the relying on risk-reduction and condoms for too long. Some, however, worry that it is too expensive; in the United States it costs upwards of $10,000 a year. Others say that it is hard enough to get people who have HIV to stick to a daily drug regimen and suggest that it’s unreasonable to expect compliance from healthy individuals. The most heated debate, however, is about whether taking PrEP will give individuals an excuse to stop using condoms and taking other precautions (such as limiting the number of partners they have) and will ultimately drive the rate of other sexually transmitted diseases up.

In May, PrEP got a big endorsement from the CDC, which released guidelines suggesting that HIV-negative individuals who are at “substantial risk for HIV infection” consider taking the drug. The agency defined those at substantial risk as: anyone in an ongoing relationship with an HIV-infected partner; gay or bisexual men who are not in a mutually monogamous relationship with an HIV-negative partner and who have had sex without a condom or been diagnosed with a sexually transmitted infection within the past six months; heterosexual men or women who are not in a mutually monogamous relationship with an HIV-negative partner and do not regularly use condoms when having sex with partners known to be at risk for HIV (such as injecting drug users or bisexual male partners of unknown HIV status); or anyone who has injected illicit drugs and shared equipment or been in a treatment program for injection drug use within the last six months.

The CDC emphasizes that PrEP is not for everyone and that those who choose to use it have to commit to taking the pill every day (at least for the period of time in which they are at risk) and must be monitored by a health-care provider and tested for HIV every three months. It also stresses that PrEP should be used alongside other prevention methods such as partner reduction, selecting low-risk partners, and using condoms.

Though the WHO’s guidelines sound broader than the CDCs, the intent is similar. Rachel Baggaley, an official with the group’s HIV department, told NPR:

We’re not suggesting that PrEP will be an appropriate choice for all men who have sex with men. It may be something that some people will want to use for a short period of their life. Or it may be appropriate for use in the long term. It will be something that they will come to a decision on with their health care provider.

The emphasis on men who have sex with men is new for the WHO but comes as the organization sees the epidemic changing in many places around the world. Baggaley explained, “In countries like Ghana, or Kenya or Nigeria, where it was once generalized, now more than 30 percent of new infections are among these key vulnerable populations.” She added that men who have sex with men are usually not targeted by existing intervention strategies and often face discrimination, stigmatization, and abuse.

In a press release, the WHO noted that rates of HIV infection among men who have sex with men remain high almost everywhere, and new prevention options are urgently needed. The organization estimates that PrEP use among men who have sex with men over a ten-year period could reduce HIV transmission by 20 to 25 percent—representing a million new infections—worldwide. In order for this to happen, however, men who have sex with men need access to PrEP. For this reason, the WHO guidelines also say that countries need to remove the legal and social barriers that prevent many people from accessing these services.