Tailoring our response to HIV micro-epidemics

How can we reduce the HIV disease burden for all in the United States

As the United States has set its sights on Ending its HIV Epidemic by 2030, there is no singular, “silver-bullet” approach that will be able to eliminate HIV transmission on its own. However, we can integrate different approaches which hold promise towards meeting this ambitious goal; this is known as taking a combination approach.

Two primary modes of addressing HIV transmission include antiretroviral treatment (known as ART, or antiretroviral therapy) and pre-exposure prophylaxis (known as PrEP). Antiretroviral treatment consists of a combination of drugs that suppress the HIV virus and prevent the progression of HIV disease. Notably, ART not only allows people living with HIV to have comparable life expectancy to those who have not contracted the virus, but, when taken daily as prescribed, it also prevents people living with HIV from transmitting the virus. The ability of ART to prevent onward transmission is a phenomenon known as “treatment as prevention.”

PrEP, first approved by the FDA in 2012, is a daily drug regimen that significantly reduces one’s chance of acquiring HIV. If someone taking PrEP is exposed to HIV through sex or injection drug use, the medicine works to keep the virus from establishing a permanent infection, and, when taken daily, reduces the risk of getting HIV from sex by 99%.

There is ongoing debate over the need for combining these two approaches. Specifically, the conversation centers on whether there is need to broadly promote PrEP use among HIV-negative individuals when there is still opportunity to substantially expand treatment for all those living with HIV. As PrEP has gained momentum, many have begun to caution overuse in low-risk populations, especially given the medication’s high cost. Instead, some advocate for prioritizing antiretroviral treatment expansion to reach global treatment as prevention targets. They argue that it provides a dual benefit: it improves health outcomes for those currently living with HIV, while also preventing people living with HIV from transmitting the infection to others.

However, a prevention approach that relies on treatment alone may not be able to fully address the burden of disease that some communities experience. In particular, given the high prevalence of HIV among Black and other gay and bisexual men of color in the United States, even extremely high levels of treatment engagement may not be sufficient to effectively reduce the number of new HIV infections, particularly within the next decade.

Black and other gay and bisexual men of color are disproportionately affected by the HIV epidemic in the United States. Despite Black gay and bisexual men having similar or fewer numbers of sexual partners and being no more likely to engage in condomless anal intercourse than white gay and bisexual men, there are substantial racial/ethnic disparities in rates of HIV, a reflection of centuries of structural racism and enduring inequities in health care, employment, and capital in the United States. If current rates of HIV transmission persist, 1 in 2 Black gay and bisexual men may be diagnosed with HIV over the course of their lifetime. Comparatively, the lifetime risk of HIV acquisition is 1 in 4 for Latinx gay and bisexual men and 1 in 11 for white gay and bisexual men. It is imperative that we consider the distribution of disease burden among various populations within the United States as we advance towards reaching national HIV elimination goals. Combination approaches are especially flexible in that they can be adjusted to suit the unique qualities of these distinct “micro-epidemics” within the United States.

The questions we must ask are, would increasing antiretroviral treatment engagement alone be sufficient to substantially reduce HIV transmission among all populations within the US? Or will it be necessary to supplement this approach with PrEP medication as well? There is no way to answer this empirically without waiting until treatment levels are increased to meet national targets, and we do not have the time to wait. This is where mathematical modeling can help us.

If current rates of HIV transmission persist, 1 in 2 Black gay and bisexual men may be diagnosed with HIV over the course of their lifetime.

To investigate these questions, we used a mathematical model to understand the added benefit that PrEP may provide in addition to scenarios where we increase antiretroviral treatment to national targets, such as ‘90–90–90’ goals, in which 90% of all people living with HIV know their HIV status, 90% of all people with diagnosed HIV infection receive sustained antiretroviral therapy, and 90% of all people receiving antiretroviral therapy have achieved viral suppression. Compiled, this scenario results in 73% of all people living with HIV achieving viral suppression. In a recent publication in AIDS Patient Care and STDs, we found that even in future scenarios in which we achieve even more ambitious ‘95–95–95’ goals — resulting in 85% of those living with HIV engaging in treatment to the point of preventing onward transmission — increasing PrEP uptake would not only be necessary but efficient in achieving the national goal of reducing the number of new infections by 90% within ten years, as outlined in the Ending the Epidemic Initiative.

Our model scenarios varied levels of PrEP use (0–90%) in potential futures where treatment engagement reached UNAIDS ‘90–90–90’ and eventual ‘95–95–95’ goals, compared to current treatment levels among Black (‘65–63–82’) and white (‘82–58–88’) gay and bisexual men in Atlanta, Georgia, the setting we used as our illustrative case study. In the model we ran, scenarios that expanded treatment to ‘95–95–95’ goals without expanding PrEP coverage were only able to reduce the number of new HIV infections by 25% for both Black and white gay and bisexual men over the course of ten years. Given the disparities of the current epidemic, this is a particularly insufficient change for Black gay and bisexual men, resulting in rates of HIV transmission that remain double those of white gay and bisexual men.

Antiretroviral therapy is extremely valuable and continuing to increase access to the highest possible levels is an urgent national and international priority. It will not, however, be sufficient to reduce HIV infections equitably among all communities within the United States.

However, we found that high levels of PrEP coverage in addition to achievement of ‘95–95–95’ goals — such as an ambitious 75% of all eligible gay and bisexual men accessing the medication — was able to reduce the number of new HIV infections by an additional 67.9%. This expansion of PrEP access is particularly important for decreasing new HIV infections among Black gay and bisexual men currently experiencing disproportionate burden of disease. The additional 67.9% transmission reductions attributable to combining 75% PrEP coverage with achieving ‘95–95–95’ treatment goals corresponded to almost triple the absolute reductions in transmission rates for Black gay and bisexual men as white gay and bisexual men in Atlanta, due to the substantial differences in burden of disease within the two populations.

Antiretroviral therapy is extremely valuable and continuing to increase access to the highest possible levels is an urgent national and international priority. It will not, however, be sufficient to reduce HIV infections equitably among all communities within the United States. As one PrEP medication finally goes generic, we have an opportunity to address the numerous social and structural barriers that prevent Black and other gay and bisexual men of color from PrEP access and engagement. Although these interventions will not reverse centuries of institutional racism, they will impact HIV transmission and benefit American lives. We must continue to acknowledge the health inequities that persist across our nation, and address the reality that “Ending the HIV Epidemic” will not happen without addressing the longstanding racial disparities that find their roots in the foundation of this country.

For more information on our study, please contact Alyson Singleton (alyson_singleton@alumni.brown.edu).

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Public health research that is people centered, place oriented, & data driven. We study drugs, infectious diseases + intersecting epidemics.

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Alyson Singleton, MA

Alyson Singleton, MA

Infectious disease dynamics and computational epidemiology. Find me on Twitter at @aly_singleton.

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