CROI 2025 Abstract eBook

Abstract eBook

Poster Abstracts

tests (102,580) but the lowest HIV screening rate. Of the 16,270 patients who received antibiotic treatment for syphilis, only 1,012 (6.22%) received HIV screening. Age-specific HIV screening rates among treated patients were: Under 20 (9.01%, 62/688), 20-29 (9.34%, 97/1,038), 30-39 (6.75%, 97/1,438), 40-49 (6.09%, 118/1,939), 50-59 (6.30%, 120/1,906), 60-69 (5.44%, 173/3,181), and Over 70 (5.67%, 345/6,080). HIV diagnosis data showed the highest number of cases in the 30-39 age group. The Advanced HIV Disease Ratio increased with age: Under 20 (10.0%), 20-29 (13.0%), 30-39 (25.4%), rising to Over 70 (56.9%) (Fig.2). Conclusions: This study reveals alarmingly low HIV screening rates among syphilis-tested and treated patients across all age groups in Japan, with particularly concerning trends in older populations. The high rate of advanced HIV disease at diagnosis in older groups, coupled with their low HIV screening rates, underscores a critical public health issue. These findings emphasize the urgent need to significantly increase HIV testing rates for all patients undergoing syphilis testing and treatment, regardless of age. The figure, table, or graphic for this abstract has been removed. 1190 Machine Learning Risk Stratification Compared With a Counselor-Guided Screening Tool Daniel G. Wandina 1 , Emmanuel K. Maingi 2 , Sharon M. Minyatta 3 , Denice O. Juma 2 , Judah M. Musau 2 , Robert Osoti Osoti 4 , Moses K. Kitheka 2 , Edmod O. Obat 5 1 Gold Star Kenya, Karuri, Kenya, 2 Deloitte & Touche, Nairobi, Kenya, 3 Gold Star Kenya, Kisumu, Kenya, 4 Gold Star Kenya, Nairobi, Kenya, 5 United States Agency for International Development (USAID) Nairobi, Nairobi, Kenya Background: Kenya has one of the largest HIV epidemics globally, with women constituting 62% of the 1.4 million people (15+ years) living with HIV. In 2023, Kenya has achieved 97% in 1st 95 recording 17 681 new HIV infections. Identifying the last 3% of individuals is becoming increasingly difficult. There’s a need to adopt targeted testing approaches hence growing interest in machine aided artificial intelligence (AI). Studies have demonstrated that 4% of males and 11% of females are at high risk of infection using machine learning. Methods: A cross-sectional data review was done on outcomes of machine aided HIV risk stratification in 95 health facilities supported by USAID Tujenge Jamii project across 4 counties in Kenya. The program trained healthcare workers on the use of machine-aided HIV risk screening in health facilities using electronic medical records at the HIV testing points in the general population. This was done alongside counselors' HIV screening, routinely comparing machine-lead outcomes and manual screening outcomes. Results: Between April 2023 and June 2024 out of 100,000 clients tested for HIV 57,450 were screened using machine Learning where 2,374(4%) were classified as very high risk 10,683(19%) as high risk,26,455(46%) as moderate risk and 17,938(31%) low risk. From the very high risk, 217 (9%) tested HIV pos, 315 (3%) from the high risk,388 (1%) of the medium risk and 141(1%) from the low risk. The 9% and 3% positivity among the Very high risk and very risk categories were significantly higher compared to 14% client screened eligible with 530,431 clients tested by following a counselor manual guided screening tool where 5,649 (1.1% ) tested HIV positive. Conclusions: Machine-aided HIV risk classification scaleup provides an opportunity to improve HIV identification and efficiency, There is a need to scale up the use of ML in HIV testing. The figure, table, or graphic for this abstract has been removed. 1191 HIV Serologic Reactivity in Persons With HIV Who Started ART During Acute/Early Stages of Infection Vivian I. Avelino-Silva 1 , Mars Stone 1 , Clara Di Germanio 1 , Eduard Grebe 1 , Brian Custer 1 , Steve Kleinman 2 , Xutao Deng 1 , Sandhya Vasan 3 , Nittaya Phanuphak 4 , Carlo Sacdalan 5 , Siriwat Akapirat 6 , Mark S. Souza 7 , Michael P. Busch 1 , Philip J. Norris 1 , for the NHLBI Recipient Epidemiology and Donor Evaluation Study-IV Pediatric (REDS-IV-P) 1 Vitalant Research Institute, San Francisco, CA, USA, 2 University of British Columbia, Vancouver, Canada, 3 Henry M Jackson Foundation, Bethesda, MD, USA, 4 Institute of HIV Research and Innovation, Bangkok, Thailand, 5 SEARCH, Bangkok, Thailand, 6 Armed Forces Research Institute of Medical Sciences in Bangkok, Bangkok, Thailand, 7 Background: Persons with HIV (PWH) who receive antiretroviral treatment (ART) beginning in acute/early stages of infection may fail to develop antibody reactivity or revert to nonreactive levels on serological assays. Seroreactivity

after prolonged viral suppression in PWH treated in acute/early stages of infection has not been previously characterized. Methods: RV254 cohort study identified PWH with recent HIV acquisition in Bangkok using an antigen (Ag)/antibody (Ab) combo-assay, with subsequent testing of nonreactive samples using a nucleic acid test (NAT) and testing of reactive samples with a less sensitive Ab-only assay. Participants with reactive results in the Ag/Ab assay and nonreactive results in the Ab-only assay, and those with nonreactive results in the Ag/Ab assay and reactive results in the NAT were included, categorized according to Fiebig stage, and offered immediate ART with longitudinal follow-up. We obtained plasma samples collected at the latest available timepoint after ART initiation to investigate seroreactivity using the Ortho VITROS HIV Ag/Ab Combo assay, according to Fiebig stage at ART initiation. Results: 345 participants with samples collected between 96 and 480 weeks after ART initiation were included; most samples (64%) were collected at 336 weeks (6.5 years) after ART initiation. At ART onset, 48, 92, 148, and 57 participants were categorized at Fiebig stages 1, 2, 3, and 4, respectively. Overall, 24 participants (7%) had nonreactive results; percentages with nonreactive serology were 38%, 2%, 1%, and 4% with ART initiated at Fiebig stages 1, 2, 3, and 4, respectively (p<0.001). Serology test results are shown in Figure 1. We found progressively lower signal-to-cutoff readouts for participants starting ART at earlier Fiebig stages, with statistical significance comparing Fiebig 1 vs. Fiebig 4 (p<0.001), and Fiebig 2 vs. Fiebig 4 (p=0.001). Conclusions: ART initiation at acute/early stages after HIV acquisition can suppress antibody reactivity, limiting HIV detectability by licensed diagnostic serologic assays for years following infection. This phenomenon is particularly relevant but not limited to PWH who initiate ART in Fiebig stages 1 and 2, before the emergence of Ab responses. Implications include false negative diagnostic testing in clinical settings, including blood donation screening. 1192 Laboratory-Based HIV-1/2 Ag/Ab Immunoassay Performance in the United States, 2019-2023 Patricia Bessler, Weiming Zhu, Allison Lale, Kevin Delaney, Ya-Lin A. Huang, Karen W. Hoover Centers for Disease Control and Prevention, Atlanta, GA, USA Background: The Centers for Disease Control and Prevention (CDC) recommends routine HIV screening of persons aged 13-64 years and additional testing for those with exposure risk or symptoms. All positive HIV antigen/ antibody (Ag/Ab) immunoassay results should be confirmed with HIV antibody differentiation and HIV RNA testing to resolve conflicting results. Understanding the performance and efficiency of HIV Ag/Ab testing in real-world settings is essential for guiding public health strategies and improving protocols for HIV diagnosis. We evaluated the performance of HIV Ag/Ab testing using data from a major commercial lab in the United States. Methods: We analyzed HIV testing data from individuals ≥ 13 years tested by Quest Diagnostics between 2019 to 2023 with complete CDC-recommended algorithm testing for a positive Ag/Ab test. We calculated the testing volume and the positive predictive values (PPV) by age group and sex. PPV were calculated as the proportion of HIV Ag/Ab tests with a positive result confirmed by the CDC recommended HIV algorithm among all Ag/Ab tests with an initial positive result. Results: We identified a total of 23,944,766 HIV Ag/Ab tests. Of these, 36.5% were performed on men and 63.5% on women, with the majority (80.0%) among individuals aged 20-54 years. Overall, the PPV of the HIV Ag/Ab test was 78.6%. The PPV was higher in men (87.5%) than in women (58.4%). For men, PPV was lowest among those aged 13−14 years (27.8%) and peaked at 89.2% for those aged 25−34 years. PPV was > 80% for men aged 20−74 years and 70.6% for men 75+. PPV was 49.7% for women of reproductive age (15-44) and increased to 74.2% for women aged 55−64 years. Except for persons aged 13−14 years, PPV was consistently lower for women compared with men. Conclusions: This analysis found relatively higher PPV among groups most likely to be tested by providers based on clinical or risk-based needs: men, persons reporting HIV exposure risk, persons initiating or continuing PrEP, and symptomatic individuals. Lower PPVs were observed among women of reproductive age, likely due to near-universal screening among pregnant women who have a low overall prevalence of HIV. The reported PPV of the Ag/ Ab test highlights the need to conduct the entire recommended HIV diagnostic algorithm to confirm an HIV diagnosis. Understanding the performance of HIV

Poster Abstracts

CROI 2025 391