Why are gay men at increased risk of HIV infection?

In the United States, gay men are more susceptible than others to the human immunodeficiency virus (HIV). Men who have sex with men (MSM) are gay men and people who may be identified in other ways, such as bisexual or heterosexual. MSM has a disproportionate risk of HIV infection.

Although men who have sex with men make up only 2% to 7% of the U.S. population, Seventy percent of all new HIV infections in 2019 belonged to this group. A third of these belong to black MSM.

There are many reasons for this, and several risk factors specific to MSM can increase the chance of infection. It is these overlapping risk factors that contribute to the high incidence of HIV in this group.

This paper takes a closer look at four key factors—physiological, sexual, social, and cultural—that put gay men and other men who have sex with men at the highest risk of HIV infection compared to all other groups.

Physiological risk factors

Not all men who have sex with men engage in anal sex. However, anal sex is one of the main ways MSM get HIV.

Unprotected anal sex, also known as unprotected anal sex, is by far the most effective way to spread the virus. In fact, anal sex without a condom is 18 times more likely to transmit HIV than vaginal sex without a condom. This is true regardless of the gender of the accepting (“bottom”) partner.

One of the main reasons for this is the structure of the rectum itself.Unlike the vagina, the vagina is lined with a dense layer of cells (called Epithelial Cells) as a barrier, the rectum has only one column of these cells. Because rectal tissues are fragile, they are also prone to rupture, allowing the virus to slip through this thin layer.

Rectal tissue is also rich in immune cells called CD4 T cells. These are the target cells for HIV infection.

Because of this, HIV can quickly establish an infection. Studies using animal models have shown that within an hour of rectal exposure, HIV can disrupt the body’s front-line immune defenses. Within 24 hours, the virus can spread throughout the body.

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Pre-exposure prophylaxis (PrEP) is a very effective drug in reducing these risks. However, due to lack of awareness and access, only about one-third of MSM reported using PrEP in 2017.


Anal sex without a condom is one of the most common ways that MSM acquires and transmits HIV. Not only is the protective layer of the rectum thinner and more fragile than the vagina, but it is rich in HIV-infected immune cells.

HIV high and low risk activities

Sexual Risk Factors

Sexual behavior, exposure, and partners are all factors that influence HIV risk.

Partners at the bottom of anal sex are 2 to 12 times more likely to have HIV than those at the top (penetration). If a person is sexually versatile (able to switch between top and bottom) then these differences will all but disappear.

Men who have sex with men also have high rates of sexually transmitted infections (STIs). Much of this has to do with the lack of inclusive education that addresses the needs of LGBTQ+ people.

Having an STI increases your chances of getting HIV. Some infections, such as syphilis, increase the risk by up to 500%.

Among the reasons for the high rate of STIs, men who have sex with men are more likely to have multiple sexual partners (of any gender) than men who have sex only with women.

MSM between the ages of 18 and 24 were more likely to have sex with a partner 5 or more years older than them. This is important to their risk because the older they get, the more sexual contact they may have.


Men who have sex with men have higher rates of STIs and are more likely to have multiple sexual partners, both of which increase the risk of HIV infection. Having an older sexual partner and having multiple types of anal sex also affects risk.

How do STDs increase the risk of HIV infection?

social risk factors

Society also plays a role in the risk of HIV infection among men who have sex with men, especially those who are black or Latino.

Poverty, racism, high unemployment, lack of government support, and poor access to health care all contribute to high HIV rates among people of color. Add in the risk factors affecting MSM in general, and it’s clear why this group is disproportionately affected.

According to 2019 data, 76% of people living with HIV in the United States have an annual household income of less than $20,000. Of these, 39% were unemployed and 18% were homeless. People of color make up the largest share of those numbers.

On top of that, people generally tend to have sex with their own race. Because of this, men of color who have sex with men are more likely to get HIV because they have smaller sexual networks and because of the fact that the infection rate is higher in communities of color than in white communities.

These intersecting risk factors exacerbate an already dire situation. According to a study by the Centers for Disease Control and Prevention (CDC), black men who have sex with men in the United States today have at least a 50 percent risk of contracting HIV.


Poverty, racism, high employment rates and unequal access to health care amplify the risk of HIV infection among MSM.

Understanding HIV Health Disparities

cultural risk factors

People living with HIV are often the target of stigma—not just because of their HIV status, but sometimes because of their sexual orientation and ethnicity. This can affect their health in a number of ways.

Some people mistakenly believe that high HIV rates among men who have sex with men confirm that gay and bisexual people are “promiscuous,” “sick,” or “immoral.” This attitude can keep many MSMs in hiding.

Rather than allow themselves to be stigmatized or discriminated against, some men may avoid HIV testing and treatment until the disease progresses beyond control.

A positive test could also force them to say how they got infected, which they may not want or be prepared to do.

If they do get tested and have HIV, many are already well aware that isolation and lack of support can lead to depression, alcohol or drug use, sexual risk-taking, and inconsistent treatment and care.

All of this explains, at least in part, why one in six men who have sex with men with HIV remains undiagnosed, compared with one in eight heterosexual men with HIV.

Among HIV-infected black MSM who may be specific targets of stigma, racism and homophobia, only 59 percent of those who received treatment remained on treatment. Among Latino men who have sex with men, these same effects translated into higher rates of injecting drug use, further spreading the disease.


Fear of stigma and homophobia keeps many men who have sex with men reluctant to seek HIV testing and treatment. Among those who test positive, isolation and lack of support can lead to depression, substance abuse, sexual risk-taking and inconsistent care.


Men who have sex with men (MSM) make up 2% to 7% of the US population, but account for about 70% of all new HIV infections each year. There are many factors that put gay and bisexual men at such high risk, including physical vulnerability, sexuality, social and economic inequality, and cultural stigma.

Because of the intersection of these and other risk factors, including racism and homophobia, black and Latino men who have sex with men are particularly affected.

What are health disparities and why are they important?