Preexposure Prophylaxis Gives Good Results in Latin America

Same-day initiation of preexposure prophylaxis (PrEP) against human immunodeficiency virus (HIV) infection is feasible in Latin America, with low early loss to follow-up, high adherence, and long-term engagement. However, questions regarding social and structural determinants of HIV vulnerability must be addressed to fully achieve the benefits of PrEP. These are the main findings of a prospective, single-arm, open-label, multicenter PrEP implementation study conducted in Brazil (14 sites), Mexico (four sites), and Peru (10 sites). From February 6, 2018, to June 30, 2021, 9979 participants were screened, and 9509 were enrolled (Brazil: n = 3928; Mexico: n = 3288; and Peru: n = 2293).

The results of the study, which is part of the Implementation PrEP (ImPrEP) project, were featured in The Lancet HIV , published on December 21, 2022.

PrEP, one of the combination prevention measures available for HIV, consists of antiretroviral agents to reduce the risk of HIV infection. Efficacy of oral PrEP (tenofovir disoproxil fumarate coformulated with emtricitabine) is linked to adherence to therapy (daily doses) and to use of other protective measures, such as a condom and lubricants.

ImPrEP was developed in 2018. Through research, it strives to widen the provision of HIV-related services in the Brazilian Public Health System (SUS), beyond just offering PrEP medication. The mission is to subsidize the development of disease control, teaching, and peer education services and to make these services available in the SUS. The project was also designed to improve services in diagnosing and treating sexually transmitted infections (STIs) and to advise and offer psychological care to those using PrEP. The project was created by the Evandro Chagas National Infectious Diseases Institute at the Oswaldo Cruz Foundation (INI/Fiocruz), Brazil, in partnership with the Brazilian Ministry of Health; Cayetano Heredia Peruvian University, Lima, Peru; and Condesa Clinic and the National Public Health Institute, Mexico.

Of the study’s 9509 participants, 795 (8.4%) were lost early to follow-up, and 6477 (68.1%) adhered to PrEP. Of the latter group, 5783 (70.3%) had long-term PrEP engagement. The odds of adherence to PrEP and long-term PrEP engagement were lower among transgender women, compared with cisgender men; lower among participants aged 18–24 years and 25–30 years, compared with participants older than 30 years; and lower among participants with primary or secondary education, compared with those with more than secondary education. Transgender women, participants aged 18–24 years, and participants with primary education had increased odds of early loss to follow-up.

All STI examinations were performed at enrollment. At baseline, the prevalence of active syphilis was 8.8%, and the overall incidence was 10.09 per 100 person-years. The prevalence of rectal chlamydia and of gonorrhea decreased from enrollment to week 52 of follow-up.

“We determined that early self-reporting on PrEP adherence at the beginning of therapy is indicative of whether an individual will have long-term adherence [to prophylactic measures],” said the study’s lead author, Valdiléa Veloso, MD, PhD, infectious disease specialist and director at the INI/Fiocruz. Another aspect Veloso emphasized was the high number of STI cases among participants. For Veloso, ImPrEP helped to highlight the need to make access to molecular testing for chlamydia and gonorrhea possible through the SUS, as these tests are expensive and are not yet available in the public health system. “As most STIs are asymptomatic, doctors need to be on the ball to detect these diseases early,” she added.

Although the study identified the presence of STIs, risk compensation did not play a role in the study; PrEP use did not increase the number of infections. Nevertheless, Veloso noted that the disparities observed among people with a lower level of education or those who experience discrimination in the healthcare setting because of their gender or race became very clear. Moreover, the incidence of HIV infections was very low, but it was higher among the populations most vulnerable to HIV infection and those with low PrEP adherence.

One of the study’s innovations was that the researchers did not wait for the results of the HIV viral load and kidney function tests to start PrEP. Instead, those interested in PrEP began taking the medication the day they contacted the health service. If the test result was positive for HIV, dolutegravir was added for antiretroviral therapy.

In Brazil, PrEP has been available within the SUS since December 2017. In December 2022, the Brazilian Ministry of Health issued Technical Note No. 563/2022, adding the use of on-demand PrEP, known as PrEP 2-1-1, as an alternative for cisgender men and transgender women who are not taking estradiol-based hormones and who have sexual relations less than twice a week, whether planned or spontaneously.

Updated in 2022, the Clinical Protocol and Therapeutic Guidelines for Pre-Exposure Prophylaxis (PrEP) for Risk of HIV Infection changed the initial dose to include a loading dose of two tenofovir disoproxil fumarate + emtricitabine tablets on the first day of use, followed by one tablet daily, in addition to changes in PrEP laboratory monitoring. The protocol also extended the recommendation for prophylaxis to all adults and adolescents aged 15 years and older with a body weight ≥35 kg who are sexually active and at higher risk for HIV infection.

According to data from the Brazilian Ministry of Health, between 2011 and 2021, 52,513 HIV-positive young adults of both sexes, aged 15 to 24 years, developed AIDS. This highlights the importance of broadening campaigns and improving guidance to make services more accessible to this population, with the aim to increase patients’ adherence to antiretroviral therapy. In 2021, the sex ratio for young adults aged 15 to 24 years was 36 males to 10 females in Brazil.

In 2023, ImPrEP will initiate a new study in Brazil on the use of a long-acting, injectable form of PrEP with cabotegravir. Titled ImPrEP/CAB-Brasil, the study will be conducted in a population composed of gender and sexual minorities, including transgender women, nonbinary, gay, and bisexual individuals, and men who have sex with men, aged 18 to 30 years, at six sites in Brazil. It will be coordinated by Beatriz Grinsztejn, MD, PhD, infectious disease specialist and researcher at the INI/Fiocruz. Veloso noted that strategies involving long-acting, injectable PrEP, such as cabotegravir, might overcome the pitfalls observed and become an option for those who have more difficulty adhering to oral PrEP.

This article was translated from the Medscape Portuguese edition.

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