In the United States, gay men are at a disproportionately high risk of getting HIV and AIDS. In 2016, 68% of all HIV infections in the U.S. affected men who have sex with men. The risk is even higher for gay black men.﻿﻿ Why are gay men more likely to get HIV?

There are several reasons why gay and bisexual men are at higher risk of HIV than their straight counterparts. Some of the reasons are based on certain types of sex that result in greater risk of infection due to how HIV is biologically transmitted.﻿﻿ Other reasons reflect social realities about how men who have sex with men (MSM) live in the world and are treated by society.

Biological HIV Risks

Not all gay men enjoy anal sex. However, anal sex is one of the main reasons that gay men have higher rates of HIV.﻿﻿

Scientists have estimated that the average HIV transmission rate during anal sex is 18 times higher than the rate during vaginal intercourse. The risk of acquiring HIV during an act of unprotected anal intercourse is estimated to be 1.4%.

Some heterosexual men and women also enjoy anal sex. However, there's another biological factor that makes anal sex riskier for gay men. They are much more likely to engage in both "topping" and "bottoming," or penetrating and receiving. This is known as role variability, and it has been shown to increase HIV transmission risk.

Why? Men who practice receptive, unprotected anal intercourse are at higher risk of contracting HIV.﻿﻿ Men who practice insertive, unprotected anal intercourse are more likely to transmit HIV to their partners. When men do both, the combination of behaviors optimizes the spread of HIV in a way not seen in heterosexual couples.﻿﻿

In heterosexual couples, men are far more likely to penetrate and women to be penetrated. Because of this, HIV is far more likely to spread from the male partner to the female partner than vice versa.﻿﻿

Societal HIV Risks

It's not just biology that makes gay men more likely to get HIV. Social institutions also play a role. In particular, it's been shown that homophobia makes it more difficult for gay men to access health care.﻿﻿ Other forms of legal and social discrimination affect their access as well.

A lack of reliable access to care can make a big difference in the spread of HIV. It can lead to delays in the diagnosis and treatment of HIV infection.

People are often most infectious during acute (new) infection.﻿﻿ That's particularly true when they don't know they're infected.

Prompt, effective treatment is also very important, as the treatment reduces infectivity.﻿﻿ In fact, that's the principle behind treatment as prevention. Therefore, delaying health care further increases HIV risk among MSM.

In addition, certain groups of gay men are at a particularly high risk for another reason. Their risk is high because a large percentage of their potential partners are infected with the virus.﻿﻿

Where more people in the community have HIV, there is a higher risk that someone will be exposed. This is particularly problematic for black MSM. They often date within very small communities. As such, their HIV risk is often higher than that of other MSM. That's true even when their behavioral and lifestyle choices are safer.﻿﻿

For example, black MSM in the United States are six times more likely to be diagnosed with HIV than white MSM.﻿﻿ That's true even though, on average, they are less likely to engage in risky behaviors. For example, they are less likely to use drugs during sex.

However, it's not just the higher risk of their partner pool that causes this disparity. Compared to other HIV positive MSM, black MSM with HIV also are less likely to:﻿﻿

Have health insurance

Be on successful cART regimens

Have a high CD4 count

These issues reflect systemic healthcare inequities related to race. Those effects are not limited to HIV or to black MSM.

Addressing the Stigma

People sometimes stigmatize gay men for their high risk of HIV. They claim that they engage in riskier behaviors, or make moral judgments about what it means to be gay.

However, AIDS isn't a gay disease. In fact, around the world, most sexually transmitted cases of HIV are spread through heterosexual intercourse.﻿﻿ So why do gay men get HIV?

Scientists have calculated that 80% to 90% of the HIV epidemic in gay men would disappear if the transmission rate during anal intercourse was the same as it is during vaginal intercourse. Role segregation could also drop the numbers by 20% to 50%.﻿﻿ Putting those two things together might get rid of as many as 95% of the HIV infections seen in gay men.

It's not primarily behavior that puts gay men at such a high risk of HIV. It's biology.

Increased access to non-judgmental healthcare would help as well. Imagine a world where gay men felt safe disclosing their sexual risk to their doctors. That could make a big difference. They might get tested more frequently. Then they could be treated sooner. In turn, early treatment would reduce the risk of men infecting their partners as well as improving their health.﻿﻿

The CDC's recommendation of universal HIV testing (for everyone, not just gay men) hasn't had a big enough effect. Very few doctors and clinics have actually been following the rules.

However, there are signs that things may be improving. When powerful data was released showing that reducing viral load reduces the likelihood of sexual transmission of HIV,﻿﻿ policies changed.

Large cities started recommending universal access to HIV treatment. They removed restrictions related to CD4 count which meant individuals with HIV had to wait to start treatment. This change could be a great boon to serodiscordant gay couples.

Reducing an infected person's viral load is not only a very effective form of treatment, but it also helps keep their sexual partners safe from infection. The discovery of this effect, known as "treatment as prevention" continues to reshape HIV policy in the U.S.﻿﻿ It is also changing the way doctors and scientists look at HIV prevention around the world.