Transgender people receiving gender-affirming hormone therapy have a 37% lower chance of acquiring HIV, and for people living with HIV, hormone therapy appears to offer a 44% lower chance of the virus remaining detectable in blood, according to a University of Michigan study.

Overall, the research found that hormone therapy for patients receiving medical care to align their physical characteristics with their gender identity improved all HIV-related health outcomes for transgender, nonbinary and gender diverse people.

The study, published in The Lancet HIV, examined health records of more than 8,000 transgender and gender diverse patients who received primary care at community health centers in Boston and New York City between 2013 and 2019.

“Trans communities have been hard hit by the HIV epidemic. Research on the health-promoting effects of hormone therapy for trans people is robust for mental health, but less so for physical illnesses such as HIV. We aimed to fill the gap with this study, said Sari Reisner, the study’s lead author and an associate professor of epidemiology at the U-M School of Public Health who recently had a study on hormone therapy and depression published.

Transgender people are about 13 times more likely to be HIV-positive than other adults of reproductive age, according to the World Health Organization. At the same time, the WHO reports that transgender individuals have lower rates of access to health services than the general population due to a range of issues, including violence, legal barriers, stigma, discrimination and socioeconomic marginalization.

It’s likely those barriers, the researchers found, contribute to higher HIV rates in Black, Hispanic/Latino and multiracial transgender people than among white transgender people.

The researchers also found that very few study participants—only about 3% of those without HIV—were taking pre-exposure prophylaxis, or PrEP, medication intended for individuals at high risk for HIV exposure, suggesting an important opportunity to expand HIV prevention efforts.

“We have public health tools to reduce HIV, including newer biomedical prevention strategies like PrEP and traditional behavioral approaches such as supporting condom use. But preventing HIV and optimizing HIV care are not ‘one size fits all’ in public health,” Reisner said. “We need tailored approaches that address the lived experiences and priorities of trans people, such as integrated models of care that incorporate gender care with HIV prevention and care services.”

The findings suggest that gender-affirming care functions as a public health intervention that addresses multiple health needs simultaneously. By providing gender-affirming hormone therapy, health care providers can potentially support a person’s gender identity while also reducing HIV transmission and improving HIV treatment outcomes in a population facing significant health disparities, the researchers found.

The study also revealed that patients who remained consistently engaged in care had better health outcomes, and, more specifically, that the number of years engaged in care was related to keeping the HIV virus in check or viral suppression high.

Reisner, who also published a Viewpoint article in The Lancet HIV examining why transgender people face higher HIV rates, suggests solutions to address the various social, economic and health care barriers that exacerbate HIV inequities. The article emphasizes the need to develop solutions in partnership with transgender communities and calls for more research and funding into research for transgender people living with HIV.

“Trans communities are made vulnerable to HIV. For trans people, HIV vulnerabilities and resiliencies are situated within the multilevel and biopsychosocial contexts in which we live,” Reisner said. “Public health cannot effectively mitigate the HIV epidemic unless we dismantle the intersecting systems of power and privilege relating to both gender and to other marginalized identities, which fuel HIV inequities.”

The study was funded by the Patient-Centered Research Outcomes Institute and the National Institutes of Health.