CROI 2016 Abstract eBook

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Poster Abstracts

were grouped according to timing of appearance, the intensities of each band was scored from 0-2+, and individual intensities or sums of bands plotted as time after first detection of infection. Results: Figure 1 shows the relative intensity of bands from 20 seroconverting individuals post first Aptima RNA positivity.Antibodies to p24, p40, gp160 and p55 (A Bands) develop quickly after infection, with maximum reactivity by 25-40 days post infection.A more slowly evolving response is seen for p31, p65, gp41, gp120 and p51, (B Bands).A WBI of A and B bands can be used to estimate time post infection between 15 days to up to 270 days with some consistency.The subtypes included in this analysis include A, B, C, D, and CRF_01AE, all of which show similar evolution profiles. I. TheWBI accurately distinguishes between new, well established, or advanced infection and provides a useful estimate of the time of HIV infection. II. Is independent of virus subtype and applicable to different populations; III. Uses results from an assay already used for confirmation of HIV infection, allowing for greater flexibility in application (including developing countries) IV. Demonstrates a low False Recency Rate, thereby offering a more accurate measurement of incidence.

516 Low Prevalence of False Prior HIV Diagnoses in Chokwe District, Mozambique Rob Nelson 1 ; Duncan MacKellar 1 ; RicardoThompson 2 ; Marcelo d. Manuel 3 ; Juvencio Bonzela 4 ; Didier Mugabe 4 ; ChunfuYang 1 ; Bharat Parekh 1 ; Daniel Shodell 5 ; Edgar Monteroso 6 1 CDC, Atlanta, GA, USA; 2 Natl Inst of Hlth Mozambique, Maputo, Mozambique; 3 Chókwè District Hosp, Chókwè, Mozambique; 4 CITSC, Chókwè, Mozambique; 5 Colorado Dept of PH and Environment, Denver, CO, USA; 6 CDC, Maputo, Mozambique Background: Recent reports suggest that many clients may be falsely HIV diagnosed using rapid HIV testing algorithms in some resource-limited settings. Population-based prevalence of false prior diagnosis (dx), however, has not been reported. As part of the Chókwè Mozambique Health Demographic Surveillance System (CHDSS), we evaluate the prevalence of false prior dx in a high HIV-prevalence district. Methods: CHDSS conducts annual demographic surveillance of approximately 95,000 residents. In 2014-15, all available household residents 15-59 years of age were offered home-based HIV Testing and Counseling and asked about prior dx, use of HIV care, and ART. The national rapid testing algorithm (RT) was conducted at the CHDSS laboratory on whole blood of prior dx clients; dried blood spots were sent to CDC for confirmatory testing (CT) of those who tested RT negative (neg) or indeterminate (ind). CT included 3 rd - generation EIA for all specimens, Multispot or Western blot (if EIA positive, pos), and gp41 total nucleic acid PCR (if EIA neg). CT-neg clients were contacted by district medical staff to offer RT re-testing, verify prior dx, and help clients understand that they are not HIV-infected. Results: The HIV prevalence among 25,344 residents tested was 20.2%. Prior dx was reported by 3170 (12.5%) clients. RT results of prior dx clients: 3132 pos, 5 ind, 33 neg. CT was conducted on 36 prior dx specimens (5 ind, 31 neg); one RT-neg and three RT-ind specimens were CT-pos. Of 32 CT-neg clients, 23 were re-contacted, and all re-tested RT-neg. When asked to verify their prior dx, ten (43%) clients reported never previously testing HIV-pos. Reasons for misclassification included misunderstanding the question, hope of receiving services, and mental illness. Assuming two RT-neg specimens not available for CT are true HIV-neg, and that all non-contacted clients are true prior dx (n=11), the maximum unweighted prevalence of false prior dx is 0.76% (24/3160). Of the 24 false prior dx clients, 21 (91.7%) showed their care and treatment client card, and 13 (54%) were confirmed by medical record or pill bottle to be on ART. Conclusions: In over 25,000 residents tested in a high HIV-prevalence district of Southern Mozambique, at least 99.2% of residents who reported a prior HIV diagnosis were confirmed to be HIV infected, suggesting self-report of prior dx is valid and that RT misdiagnoses are rare. Although reassuring, the few confirmed false prior dx underscores the need to confirm infection before ART initiation. 517 HIV Incidence Assay Performance Required to Monitor Prevention Intervention Impact Neil T. Parkin 1 ; Stefano Ongarello 2 ; Jennifer Osborn 2 ; Eduard Grebe 3 ; Simon Daniel 3 ; AlexWelte 3 ; Christine Rousseau 4 ; Reshma Kassanjee 5 ; Peter Dailey 2 1 FIND, Belmont, CA, USA; 2 FIND, Geneva, Switzerland; 3 SACEMA, Stellenbosch, South Africa; 4 Bill and Melinda Gates Fndn, Seattle, WA, USA; 5 Univ of Cape Town and Stellenbosch Univ, Cape Town, South Africa Background: Cross sectional, ‘Recent Infection Testing Algorithm’ (RITA)-based estimation of national HIV incidence is being implemented in several African countries in 2015-17. The sample sizes (SS) and associated implementation costs required for precise estimation of incidence (I) are driven by the prevalence (P), I, the mean duration of recent infection (MDRI), and the false recent rate (FRR), which vary with HIV subtype and ART coverage. We sought to evaluate the potential applicability of a RITA combining the limiting antigen immunoassay (LAg) and viral load (VL) to assess the impact of population-level prevention interventions (PLPI) nationally and in key populations (KP). We also describe features of new RITAs that would enable broader implementation for these and other applications. Methods: SS were calculated using publicly available spreadsheet tools and R customizations, for assessment of the impact of an intervention that reduces I by 50%, with power 0.8 at alpha 0.05, with correction for design effect. We used an MDRI of 130 days (d) and FRR of 0.25% for LAg+VL (cutoff 1000 copies/ml), and compared this to MDRI 160 d (LAg+VL cutoff 100 copies/ml) and 240 or 280 d as aspirational targets. Surveys were considered feasible if SS was below 30,000 (national) or 5000 (KP). National P and I data for 2014 as reported by UNAIDS were used. Results: Target SS for African countries with P>4% or I>0.3% for PLPI, and for one KP are shown in Table 1. With LAg+VL 1000 , PLPI surveys were feasible in 6 countries. If the MDRI could be increased to 280 d, SS would be reduced by approximately 60%, and surveys were feasible in an additional 5 countries. In countries with non-C subtypes, such as Cameroon, Kenya, Tanzania and Uganda, SS may be underestimated due to FRR>0.25%, but the impact of elevated FRR is dampened at longer MDRI. KP surveys in young women in South Africa (a high prevalence/incidence KP example) required SS >5000 but were feasible with MDRI of ≥240 d. Conclusions: The currently available RITA of LAg+VL has limited applications for national PLPI surveys unless SS larger than 30,000 are considered; outside of high I settings it may generate imprecise estimates that are not able to detect large reductions in I. Similarly, LAg+VL surveys may not be feasible in KP surveys due to SS requirements. Development of new incidence assays with longer MDRI (≥240 d) and low FRR are needed to enable broader and more cost-effective use in national surveys, as well as for applications in PLPI and KP surveys.

Poster Abstracts


CROI 2016

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