CROI 2025 Abstract eBook

Abstract eBook

Poster Abstracts

lowest among women (2.7 per 10,000) and the 50+ year-olds (2.8 per 10,000). Differences in proportion were observed for sex (p<0.01) and age group (p<0.01). Conclusions: MSM and 15-24 years old had the highest risk of recent HIV infection. Focused prevention strategies for MSM and young men, enhanced surveillance, and further investigation into the behavioral and structural drivers of these disparities may reduce HIV transmission.

ATHENA cohort. In addition, we leveraged genetic data to investigate transmission clusters focusing on the youngest generation (i.e., Gen-Z) of MSM living with HIV-1. Methods: MSM diagnosed with HIV-1 between 1998 and 2023 were included in this study. Generations of MSM were defined by year of birth according to a timeline of “social generations” in the Western world. The youngest generation, “Gen-Z”, was born between 1997-2012, “Millennials” between 1981-1996, “Gen-X” between 1965-1980, and “Boomers” in 1964 or earlier. For individuals with a partial polymerase sequence available including at least the first 600 nucleotides of the reverse transcriptase gene, HIV-TRACE was used to identify transmission clusters of sequences with ≤1.5% genetic divergence. Results: Between 1998 and 2023, 13,307 MSM were diagnosed with HIV-1 in the Netherlands. Figure 1 shows these by year of diagnosis and generation. The overall number of annual new HIV-1 diagnoses has decreased since 2008. Initially this overall decrease reflected decreasing diagnoses among both the “Boomers” and “Gen-X”. Diagnoses among “Millennials” increased until 2013, and peaked lower and earlier within their generation timeline compared to “Gen-X”. From 2015, HIV-1 was also observed among “Gen-Z”. In total, 201 “Gen-Z” were diagnosed by 2023, compared to 192 “Millennials” in their first nine years with HIV-1 (1999-2008).A HIV-polymerase sequence was available from 6,744 MSM, including for 92 ”Gen-Z” MSM. Of these, 48 (52%) “Gen-Z” had no phylogenetic link to anyone else in the cohort. The remaining 44 (48%) “Gen-Z” were linked to 32 transmission clusters: 11 clusters were already present before 2015 and included a median of 17 (IQR:12-53) persons per cluster, 21 clusters were first observed after 2015 and included a median of 2 (IQR:2-3) persons per cluster. Conclusions: There is lacking evidence that “Gen-Z” MSM are less affected by HIV-1 than “Millennials”, and the decline of new diagnoses seen in other generations is not reflected in “Gen-Z”. “Gen-Z” MSM are part of both existing and new transmission clusters. These findings on generational dynamics can guide targeted interventions to prevent HIV-1 transmission in different generations.

1126 Recent HIV Infection Among Youth in Thailand: Who Is at Risk? Suvimon Tanpradech 1 , Benjawan Roudreo 2 , Theerawit Tasaneeyapan 1 , Thitipong Yingyong 2 , Sanny Northbrook 1 , Jennifer Favaloro 3 , Supiya Jantaramanee 2 , Apiratee Kanphukiew 4 , Panupit Thiengtham 2 1 US Centers for Disease Control and Prevention Nonthaburi, Nonthaburi, Thailand, 2 Ministry of Public Health, Nonthaburi, Thailand, 3 Centers for Disease Control and Prevention, Atlanta, GA, USA, 4 Thailand Ministry of Public Health–US CDC Collaboration, Nonthaburi, Thailand Background: Youth (defined as 15–24-year-old) are at risk of HIV infection due to their sexual activity and related risk behaviors. In Thailand, there were an estimated 4,247 (46%) new HIV infections among youth in 2023. We describe characteristics of newly diagnosed HIV positive youth with test results suggesting recent HIV infection in 9 provinces in Thailand. Methods: Newly reported HIV-positive individuals aged ≥15 years living in 9 provinces were enrolled in national recent HIV infection surveillance between September 2022 and March 2024 after providing informed consent. All blood samples were tested with a rapid infection testing algorithm (RITA) using Asante HIV-1 rapid test for recent HIV-1 infection (RTRI) and baseline CD4 to identify individuals who were infected in the past 12 months. We used case surveillance to exclude individuals with prior HIV diagnosis and ART history. RITA-recent was defined as RTRI-recent and CD4>200. Multivariate logistic regression analyses were used to explore the association between RITA-recent infection and potential risk factors such as sex, nationality, marital status, employment, sexual orientation, and geographic region among youth. A separate analysis comparing RTRI-recent (n=709) and RITA-recent (n=708) cases was conducted to identify any discordance between the two approaches. Results: Of 708 newly diagnosed youth, 64 (9.0%) tested RITA-recent. Of these, 61 (95%) were male, 60 (94%) were Thai, 57 (89%) were single, 29 (45%) were students, 54 (84%) were bisexual or men who have sex with men, and 28 (44%) lived in Bangkok. In multivariate analysis, being single (AOR 2.51; 95% CI 1.03–7.19) compared to married and living in the Northern region (AOR 5.80; 95% CI 1.66–23.7) compared to the Central region were risk factors for testing RITA-recent. A separate analysis comparing RTRI-recent and RITA-recent results revealed the same risk factors: single (AOR 3.08; 95% CI1.28–8.73) and living in the Northern region (AOR 4.26; 95% CI 1.38–14.2). Conclusions: Our data suggest that single youth living in the Northern region are at a higher risk of HIV acquisition. Our findings underscore the importance of implementing immediate and targeted public health interventions tailored to this particular youth group to effectively reduce HIV incidence. 1127 New HIV-1 Diagnoses Amongst Different Generations of MSM in the Netherlands: Focus on Gen-Z Daniela Bezemer 1 , Ard van Sighem 1 , Newton Otecko 2 , Danja Sarink 3 , Laura Koster 1 , Matthijs Welkers 4 , Thijs van der Laar 5 , Jeroen van Kampen 6 , Annemarie M. J. Wensing 7 , Marc van der Valk 1 , for the ATHENA Cohort 1 Stichting HIV Monitoring, Amsterdam, Netherlands, 2 Oxford University, Oxford, UK, 3 National Institute for Public Health and the Environment, Bilthoven, Netherlands, 4 Amsterdam University Medical Centers, Amsterdam, Netherlands, 5 OLVG, Amsterdam, Netherlands, 6 Erasmus University Medical Center, Rotterdam, Netherlands, 7 University Medical Center Utrecht, Utrecht, Netherlands Background: We explored how different generations of men having sex with men (MSM) contributed to the overall decrease in annual new HIV-1 diagnoses in the Netherlands using demographic data from the national observational

Poster Abstracts

1128 Development of an HIV Risk Prediction Model Using Electronic Health Record Data in Spain Maria L. Alamillo 1 , Miguel García-Deltoro 2 , Juan González del Castillo MD, PhD 3 , Yesika Díaz 1 , Maria Sainz 4 , Domingo Mérida 4 , Carolina Terrisse 4 , Antonio Castro 4 , Arkaitz Imaz 5 , José L. Enríquez 1 , Miguel León 1 , Inma Jarrin 6 1 Telómera, Madrid, Spain, 2 Hospital General de Valencia, Valencia, Spain, 3 Hospital Clinico San Carlos, Madrid, Spain, 4 Gilead Sciences, SL, Madrid, Spain, 5 Bellvitge University Hospital, Barcelona, Spain, 6 Instituto de Salud Carlos III, Madrid, Spain Background: In Spain, 7.5% of people living with HIV (PWH) are unaware of their infection, and 48.6% of those diagnosed with HIV in 2022 had a late diagnosis. Our aim was to develop a tool based on electronic health records (EHR) and HIV compatible indicators that could help identify people to test and bring to light undiagnosed HIV and reduce late diagnosis. Methods: A retrospective analysis was performed using EHR from Telotron (European Medicines Agency registered database with 2.2 million individuals anonymized data from the Spanish national healthcare system since 2012 until present). Two distinct cohorts were randomly selected in October 2023.

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