CROI 2025 Abstract eBook

Abstract eBook

Poster Abstracts

among cisgender women in the only trial conducted to date; use of doxycycline PEP in that trial was low. Methods: We describe 35 breakthrough cases of incident Chlamydia trachomatis among 32 participants assigned to doxycycline PEP (n=224) within an open-label randomized trial among 449 cisgender women aged 18-30 years in Kisumu, Kenya. Participants returned quarterly over one year for STI testing and behavioral surveys for a total of 854 visits when participants were assigned to take doxycycline PEP and 753 visits when not on a medication hold. Covariates potentially associated with incident C. trachomatis detection were assessed using Poisson regression using generalized estimation equation methods. Results: Breakthrough cases of C. trachomatis occurred throughout the study period, 6/35 (17.1%) at Month 3, 13/35 (37.1%) at Month 6, 12/35 (34.3%) at Month 9, and 4/35 (11.4%) at Month 12. Participant age <24 years was associated with incident C. trachomatis , RR 2.50, 95% CI 1.26-4.94, p = 0.008 (Table). The number of sexual partners in the prior 3 months did not differ by C. trachomatis detection (Table). There was no difference in report of recent transactional sex by breakthrough C. trachomatis case detection. The majority (24/34,70.6%) reported having vaginal sex two or more times per week in the prior 3 months with no difference in median number of times in prior 3 months, RR 0.99, 95% CI 0.99-1.00, p=0.138 (Table). Forced sex occurred with 4 reported events in prior 3 months among 854 study visits. Doxycycline PEP was inconsistently taken during the 30 days prior to visits with breakthrough cases of C. trachomatis with 11/35 (31.4%) reports of one or more missed doses with condomless sex and 6/35 (17.1%) reports of not taking any doxycycline. Among participants actively assigned to doxycycline PEP, incident C. trachomatis was associated with reporting a missed dose of doxycycline PEP (11/33, 33.3%) in the prior 30 days versus when no C. trachomatis was detected (108/720, 15.0%), RR 2.66, 95% CI, 1.31-5.43, p = 0.007 (Table). Conclusions: Detection of incident C. trachomatis among participants assigned to take doxycycline PEP occurred in the setting of a range of experiences with sexual exposures and self-reported doxycycline PEP use. Age less than 24 years and missed doses of doxycycline PEP were associated with incident C. trachomatis in women.

familiarity with doxy PEP guidelines, prescribing habits, and desire for education. The client survey assessed sexual behaviors and awareness and acceptability of doxy PEP. Results: There were 156 respondents (136 providers, 20 clients). Demographic information is in Table 1. Among providers, 25.0% (34/146) were trained in Infectious Diseases (ID). More than half (52.2%, 71/136) were familiar with doxy PEP guidelines. Only 25.0% (34/136) had prescribed doxy PEP, and 67.6% (23/34) had prescribed it <5 times in the past 6 months. ID providers were more likely to have prescribed doxy PEP than other providers (41.2% vs 19.6%, p=0.01). Six (4.4%) providers had prescribed doxy PEP to individuals AFAB. Of those who had not prescribed doxy PEP, 81.4% (83/102) believed there was enough evidence to prescribe it going forward and 72.8% reported they would like training. Among clients AFAB, 9 (45.0%) identified as LGBTQ+, 3 (15.0%) reported >/=5 partners in the past 6 months, 9 (45.0%) reported having sex more than once per week, and 7 (35.0%) had prior knowledge of doxy PEP. Responses on likelihood of using doxycycline to prevent STIs (“if available and suggested by your provider”) were 50.0% (10/20) “very likely,” 35.0% (7/20) “likely,” and only 15.0% (3/20) “unlikely.” Conclusions: Doxy PEP prescribing is not widespread in Southeastern Louisiana, although there is willingness to prescribe among providers; educational initiatives are needed. Additionally, clients AFAB have some awareness and strong acceptability of doxy PEP. Although our client sample is small, these are the first data to our knowledge on doxy PEP acceptability in persons AFAB in the US and are encouraging for feasibility of future trials.

Poster Abstracts

1279 Factors Influencing Doxy-PEP Awareness Among Sexual/Gender Minorities: A Web-Based Survey in Brazil Mayara Secco Torres da Silva 1 , Thiago Torres 1 , Carolina Coutinho 1 , Brenda Hoagland 1 , Emilia Moreira Jalil 1 , Marcos Benedetti 2 , Cristina Pimenta 2 , Sandra Wagner Cardoso 1 , Paula Luz 2 , Valdilea Gonçalves Veloso 1 , Beatriz Grinsztejn 1 1 Instituto Nacional de Infectologia Evandro Chagas, Rio de Janeiro, Brazil, 2 Fundação Oswaldo Cruz, Rio de Janeiro, Brazil Background: Sexual and gender minorities (SGM) face a disproportionate burden of sexually transmitted infections (STIs) worldwide, particularly in Latin America. While doxycycline post-exposure prophylaxis (doxy-PEP) is recommended in some countries to prevent bacterial STIs, no official guidelines or implementation studies have been conducted in any country of the Global South. This study aims to identify factors associated with awareness of doxy-PEP among SGM in Brazil. Methods: A cross-sectional online survey was conducted among adults (18+ years) living in Brazil, recruited via advertisements on dating apps (Scruff and Grindr) and social media (Instagram and Facebook) from August-September 2024. Doxy-PEP awareness was defined as having ever heard of it, and logistical regression analysis was used to identify factors associated with this awareness. Results: We enrolled 5,007 respondents, with median age 39 years (IQR:33.47), predominantly cisgender men (94.7%) residing in capital cities (78.8%), self-identified as white (55.6%) and having post-secondary education (75.8%). Although there was significant interest in STI prophylaxis (n=4434; 88.6%), only 34.1% (n=1707) reported prior doxy-PEP awareness. Doxy-PEP awareness was positively associated with having higher education, higher HIV knowledge, more sex partners, engagement in condomless anal sex, chemsex, and having an STI diagnosis in the past 6 months. Conversely, doxy-PEP awareness

1278 Acceptability of Doxycycline as Post-Exposure Prophylaxis in Southeastern Louisiana

Shafay Shams 1 , Jared Barrilleaux 1 , Blane Edwards 1 , Clare Kelsey 1 , Hope Oddo Moise 1 , Leandro Mena 1 , Patricia Kissinger 2 , Rebecca Lillis 1 , Meredith Clement 1 1 Louisiana State University, New Orleans, LA, USA, 2 Tulane University, Metairie, LA, USA Background: Louisiana ranks first in the nation for chlamydia incidence and third for gonorrhea, necessitating effective prevention strategies for sexually transmitted infections (STIs). Doxycycline post-exposure prophylaxis (doxy PEP) has emerged as a promising prevention strategy, but its success relies on acceptability among healthcare providers and clients. In particular, it is important to understand acceptability of doxy PEP among persons assigned female at birth (AFAB), who stand to gain substantial benefit but for whom doxy PEP has not yet demonstrated clinical efficacy. Methods: A survey was administered to healthcare providers across various specialties and clients AFAB in Southeastern Louisiana. Clients had multiple partners or an STI diagnosed in the past 2 years. The provider survey assessed

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