CROI 2024 Abstract eBook

Abstract eBook

Poster Abstracts

age-37 years (IQR:28-57 years); 248/450(55%)-male, 61/450(13.6%)- contacts, 259/450(58%)-vaccinated. 233/450 (52%) had comorbidities, 192/450 (43%) were SARS-COV-2 positive, 5/192(3%) were admitted to ICU, 2 deaths occurred. 87/192(45.3%) had RT-PCR (CT<30); SARS-LAMP detected 64/87(73.6%):sensitivity-73.6%(95% CI:63.0.%-82.4%); specificity-100% 95% CI:98.6%-100.0%). 67/192(34.9%) were RAT positive; SARS-LAMP detected 37/67(55.2%) :sensitivity-55.2% (95% CI:42.6%-67.4%); specificity-100% (95% CI:98.6%-100.0%). SARS-LAMP was 67/68(98%) acceptable to cases and contacts of COVID-19; 4/4(100%) user-friendly to laboratory technicians. Conclusion: SARS-LAMP's sensitivity was comparable to previous studies. It was acceptable patients and user-friendly to laboratory technicians. 1085 Estimation of Recent HIV Infections in Japan Using a Novel Testing Algorithm With Chronological Tree Teiichiro Shiino 1 , Shuzo Matsushita 2 , Tadashi Kikuchi 3 , Machiko Otani 3 , Kazuhisa Yoshimura 4 , Wataru Sugiura 1 , for the Japanese Drug Resistance HIV- 1 Surveillance Network Background: In Japan, approximately 30% of newly diagnosed individuals with HIV are identified after the onset of AIDS symptoms, suggesting that the diagnosis of people living with HIV is delayed. The lack of a serological avidity assay in Japan's surveillance system makes it difficult to accurately estimate HIV incidence. Therefore, we developed a recent infection testing algorithm (RITA) using the viral sequence-based time of the most recent common ancestor (tMRCA), based on information from our drug resistance surveillance instead of the avidity assay, and investigated the recency of some major domestic transmission clusters (dTCs) in Japan. Methods: The Japanese HIV Drug Resistance Surveillance Network has monitored the dTC dynamics of newly diagnosed HIV-1 cases in Japan using our search program for HIV nationwide clusters by sequence (SPHNCS), which stored 10,445 newly diagnosed cases between 2003 and 2022. We extracted the viral sequences and clinical information of three subtype B and one CRF01_AE dTCs prevalent during 2018–2022 and singleton cases from SPHNCS and inferred their chronological phylogeny using BEAST1. Based on the tMRCAs between neighboring cases in the phylogeny, CD4+ T-cell count, viral copy number, and possibility of an acute infection, we constructed a RITA estimating the probability of recent or late diagnosis of each case. Results: The cases available for our RITA was 529 in 2018, which decreased to 441 in 2020 and halved to 332 in 2022. All four targeted dTCs had men who have sex with men as a major risk factor. The recency of major dTCs in 2018–2022 ranged from 23.4 to 28.9%, and the recency of singleton cases was 10.0%. The overall estimated recency was 20.3%, assuming that other dTC affiliation cases are similar to major dTCs. The annual recency for each dTC was mostly less than 25%; however, it was >30% in 2018 for B-TC21 and in 2018–2019 for AE-TC2, when outbreaks were observed in a region. The annual recency estimates for the total population consistently decreased, from 24.3% in 2018 to 15.7% in 2022. Conclusion: Our results showed that before 2019, HIV testing in Japan rapidly diagnosed ongoing HIV transmission in some local risk populations, but this was not the case after 2020. As the number of positive cases decreased, HIV testing opportunities also decreased during the COVID-19 pandemic, which may have been a barrier to early detection. The decline in diagnoses of recent infections suggests a problem with the testing system in Japan. 1 National Center for Global Health and Medicine, Tokyo, Japan, 2 Kumamoto University, Kumamoto, Japan, 3 National Institute of Infectious Diseases, Tokyo, Japan, 4 Tokyo Metropolitan Institute of Public Health, Tokyo, Japan

were exposed. In a randomized control trial comparing two testing models, the test-all (TA) model (testing offered regardless of screening outcome) identified more SARS-CoV-2 positive cases than the ST model. It is important to determine costs and cost-effectiveness associated with implementation of the TA model compared to the ST model prior to expansion. Methods: The total costs of implementing TA and ST in Cameroon and Kenya were estimated from a health systems perspective using a micro costing method. The cost per client tested (PCT) and tested positive (PCTP) were estimated by dividing the total cost of each model by the number of clients tested and tested positive, respectively. A decision tree designed in TreeAge and cost-effectiveness acceptability curve were used to compare the cost-effectiveness of the two models. One-way sensitivity and probabilistic sensitivity analyses were used to assess the effect of uncertainties in key parameters on costs per client and cost-effectiveness, respectively. Results: In Cameroon, the total cost of TA was $141,942 and ST was $48,020. In TA model, the cost PCT was US$8 and the PCTP for SARS-CoV-2 was $509, whereas in the ST model the cost PCT was $25 and the cost PCTP was $728. The biggest expenditure in the TA model was SARS-CoV-2 antigen rapid diagnostic tests (Ag-RDT), 61% ($86,853), and for ST was personnel, 39% ($18,592). In Kenya, the total cost of TA was $39,264 and for ST was $27,500. In the TA model the cost PCT for SARS-CoV-2 was $13 and PCTP was $1,190, whereas in the ST model the cost PCT for SARS-CoV-2 was $125 and PCTP was $1,250. In both models in Kenya, the biggest expenditure was personnel, which corresponded to 45% ($17,696) in TA and 56% ($15,267) in the ST model. In both countries, TA model was more cost-effective. Conclusion: With the current global efforts to lower the price of SARS CoV-2 Ag-RDT, TA model is likely to be more cost-effective. The widespread implementation of TA model, as done in this project, would help identify priority areas for vaccination and individuals with SARS-CoV-2 infection early for treatment/quarantine. When budgeting for expansion of TA model, the estimated population size, costs of SARS-CoV-2 Ag-RDT, and personnel must be accurate, since they were shown in the sensitivity analysis to have the biggest impact on costs per client and cost-effectiveness. 1084 Validation and Acceptability of SARS-CoV-2 Loop-Mediated Isothermal Amplification Test in Malawi Maggie Nyirenda-Nyang'wa 1 , Mercy Kamdolozi 2 , Harry Meleke 2 , David Chaima 2 , Vincent Samuel Phiri 2 , Thomas Waterfield 3 , Nedson Bondera 4 , Maganizo B. Chagomerana 5 , James McKenna 3 , Thandie Mwalukomo 2 , Chisomo Msefula 2 , Tonney Nyirenda 2 , Derek Fairley 3 , Mina Hosseinipour 6 , for the SARS LAMP Group 1 University College London, London, United Kingdom, 2 University of Malawi, Blantyre, Malawi, 3 Queen's University Belfast, Belfast, United Kingdom, 4 Queen Elizabeth Central Hospital, Blantyre, Malawi, 5 University of North Carolina Project–Malawi, Lilongwe, Malawi, 6 University of North Carolina at Chapel Hill, Chapel Hill, NC, USA Background: Real-time-reverse-transcription-Polymerase-Chain-Reaction (RT-PCR) is the gold-standard diagnostic test to confirm SARS-CoV-2 infection however RT-PCR is expensive requiring specialist laboratories. Alternatively, optimised nucleic-acid-tests such as SARS-CoV-2-reverse-transcriptase-Loop mediated-isothermal-AMPlification (SARS-LAMP) could minimise costs and enable testing in settings without specialist laboratories. We evaluated the diagnostic test accuracy (DTA)-(sensitivity detecting cycle-threshold (CT) values <30; specificity >95%), acceptability and user-friendliness of SARS-LAMP test. Methods: Following optimisation of SARS-LAMP, a DTA study was conducted at Queen-Elizabeth-Central-Hospital (QECH) COVID-19 testing centre in Southern Malawi between September 2021-January 2022. Nasopharyngeal swabs were collected and tested for SARS-COV-2 by laboratory technicians using SARS-LAMP at Kamuzu-University-of-Health-Sciences (KUHes) laboratory. The reference standard test was defined as RT-PCR or rapid-antigen-testing (RAT) for SARS-CoV2 performed using any commercial platform at QECH. We calculated sensitivity and specificity of SARS-LAMP compared to existing commercial tests. SARS-LAMP's user-friendliness by laboratory technicians (n=4) and acceptability by suspected cases of COVID-19 and contacts (n=68) were assessed using semi-structured interviews. Likert scales were analysed using summation analysis. Major themes and subthemes were identified. Results: 105 retrospective nasopharyngeal swabs samples were analysed during optimisation and SARS-LAMP had sensitivity-73.7%(95% CI:65.3%- 89.2%); specificity-100%(95% CI:100.0%-100.0%). The prospective DTA study recruited 450 participants using convenience sampling. Median

Poster Abstracts

CROI 2024 351