Latin American CROI 2024
Lessons From Latin America: HIV PrEP and Mpox Data From CROI 2024

Released: March 29, 2024

Expiration: March 28, 2025

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Key Takeaways
  • Data from the ImPrEP study suggest that medication possession ratio and self-reported information are effective and simple measures to monitor adherence in PrEP programs.
  • Further data from the ImPrEP study showed that social determinants of health, particularly education and perception of risk, played a significant role in PrEP adherence among young adults in Latin America.
  • Late-breaking data from Brazil demonstrated that people living with HIV who are not engaged in HIV care could be more vulnerable to Mpox.

The HIV epidemic in Latin America disproportionally affects men who have sex with men, transgender women, and young men who have sex with men. This disparity is fueled by LGBTQIAPN+ phobia, stigma, and social determinants of health. Several impactful abstracts from CROI 2024 highlighted how these factors affect adherence to pre-exposure prophylaxis (PrEP) and their far-reaching consequences on the national response to other diseases, namely Mpox.

PrEP Adherence in Latin America
Ensuring adherence in PrEP programs is essential for tailoring prevention strategies and enhancing engagement in healthcare. The ImPrEP study, conducted from 2018-2021, implemented same-day oral PrEP (tenofovir disoproxil fumarate [TDF]/emtricitabine [FTC]) for 9509 men who have sex with men/transgender women in Brazil, Mexico, and Peru. At CROI 2024, 2 abstracts presented secondary data concerning PrEP adherence among ImPrEP study participants.

One abstract compared 2 indirect adherence measures with dried blood spots (DBS): medication possession ratio, defined as the ratio between tablets dispensed in the prior visit and days between the 2 visits, and self-reported adherence, defined as self-reported 30-day recall.

The other abstract focused on identifying factors associated with nonprotective TDF/FTC levels in DBS among transgender women and young men who have sex with men to assess determinants of adherence.

In the comparison of 2 indirect adherence measures with DBS, 4274 DBS samples from 2096 participants were analyzed. Most participants (81%) were men who have sex with men, and 19% were transgender women. Of all DBS samples, 67% exhibited protective drug levels.

Investigators used estimating equations and area under the curve (AUC) analysis to assess the accuracy of both indirect adherence measures in relation to the DBS analysis. The AUC for medication possession ratio was 0.75 (95% CI: 0.74-0.77) compared with 0.76 (95% CI: 0.74-0.78) for self-reported adherence. Both medication possession ratio and self-reported adherence effectively distinguished protective levels of PrEP among key populations in Latin America, with no significant difference between assessment methods.

I believe these cost-effective and easily implementable measures could serve as valuable tools for monitoring PrEP programs.

In the analysis examining factors linked to nonprotective TDF/FTC levels in DBS, data from 3573 DBS samples representing 1802 young men who have sex with men/transgender women were analyzed.

Among the young participants, 94% identified as men who have sex with men, and 14% were 18-19 years of age. Of the participants who identified as transgender women, 27% were 18-24 years of age.

Among all young participants, coming from Peru, possessing a limited educational background (completing only primary or secondary education), and engaging in sex work were associated with higher odds of inadequate PrEP adherence. Identifying as a transgender woman also was associated with inadequate adherence, and within the transgender women subgroup, being 18-24 years of age was further associated with suboptimal PrEP adherence.

By contrast, factors such as using poppers and having 11 or more sexual partners were associated with lower odds of inadequate adherence for all young participants, and reporting condomless anal sex was associated with lower odds of inadequate adherence among transgender women in particular.

I think these data showed that social determinants of health, particularly education, played a significant role in PrEP adherence among transgender women and young men who have sex with men/transgender women in Latin America. HIV risk perception may have influenced adherence to PrEP, particularly concerning sexual behavior.

To expand PrEP programs in the region, particularly among the most vulnerable groups, such as young men who have sex with men/transgender women with lower education and those engaged in sex work, tailored interventions addressing stigma within health services are essential. Employing long-acting PrEP could be a strategic approach to improve adherence in these populations.

Lessons From Recent Mpox Outbreaks in Brazil
During a late-breaking session at CROI, Dr Mayara Secco Torres da Silva from the Evandro Chagas National Institute of Infectious Diseases, Fiocruz, presented an abstract titled “A New 2023-2024 Mpox Outbreak in Brazil: Lessons From a Re-emerging Neglected Disease,” reporting findings on a recent Mpox outbreak.

In 2022, Brazil experienced the second-worst Mpox outbreak after the United States. Analysis of this earlier outbreak, which began in 2022 and continued into 2023, revealed that Black Brazilians, individuals with a secondary school education or less, and men who have sex with men were disproportionately affected.

The more recent 2023-2024 outbreak reported at CROI showed a higher incidence of Mpox among people living with HIV and PrEP users compared with the initial 2022-2023 outbreak. Dr Torres da Silva highlighted that as community transmission escalates, people living with HIV who are not engaged in HIV care, including late presenters and those lost to follow-up, may become increasingly vulnerable to severe courses of Mpox diseases.

In all, the ongoing 2023-2024 Mpox outbreak in Brazil showcases the importance of overcoming the barriers that relegate Mpox to a neglected disease. Of note, Dr Torres da Silva emphasized that Brazil and other low- and middle-income countries still lack access to the smallpox vaccine, which played a pivotal role in controlling the Mpox outbreaks in the United States and Western Europe. This calls for sustained efforts to control Mpox, emphasizing the need for more equitable distribution of health technologies worldwide and the need to address structural determinants that continue to affect HIV continuum of care outcomes in Global South countries.

Your Thoughts?
How do you think the data from these studies in Latin American relate to trends that you see in your own practice? How do you think this data will affect the response to HIV and emerging diseases in the future? Leave a comment to join the discussion.