Performance of Determine Combo and other point-of-care HIV tests among Seattle MSM

Seroconversion, seroreversion, and serowaffling among participants initiating antiretroviral therapy in Project DETECT

BACKGROUND

Incomplete HIV seroconversion and seroreversion are increasingly documented by testing and pre-exposure prophylaxis programs more than previously recognized. This analysis reports on incomplete seroconversion and seroreversion by specimen and test type among Project DETECT participants.

METHODS

Project DETECT included a longitudinal study of point-of-care tests. Participants were categorized as having "incomplete seroconversion" if all timepoints had ≥1 nonreactive test at study censoring. Among participants with incomplete seroconversion, we defined "seroreversion" as sustained regression to nonreactive for any test following a reactive result. We define "serowaffling" as any reactive result followed by a nonreactive and then reactive result. We used Fisher's exact tests to explore relationships between Fiebig stage at ART initiation and incomplete seroconversion, seroreversion, and serowaffling.

RESULTS

Twenty of 1940 Project DETECT participants met criteria for this subset. Ten participants had complete seroconversion after a median of 23 (IQR 16-47) days following initial positive tests. Ten participants had incomplete seroconversion, eight of whom had seroreversion. Incomplete seroconversion with persistent nonreactive tests was seen only with oral fluid (OF). Of eight participants with seroreversion, all experienced seroreversion of OF tests if the test was ever reactive (n = 6); seroreversion occurred in fingerstick and venipuncture tests in two participants. Serowaffling occurred in nine (45%) participants. No associations were seen between Fiebig stage at ART start and complete seroconversion, seroregression, or serowaffling in our sample.

CONCLUSIONS

OF tests may be particularly susceptible to providing false-negative results. Seroreversion and incomplete seroconversion among individuals on antiretroviral treatment may represent a growing problem for HIV testing and treatment programs.

Comparison between HIV self-testing and facility-based HIV testing approach on HIV early detection among men who have sex with men: A cross-sectional study

Background

To assess whether HIV self-testing (HIVST) has a better performance in identifying HIV-infected cases than the facility-based HIV testing (HIVFBT) approach.

Methods

A cross-sectional study was conducted among men who have sex with men (MSM) by using an online questionnaire (including information on sociodemographic, sexual biography, and HIV testing history) and blood samples (for limiting antigen avidity enzyme immunoassay, gene subtype testing, and taking confirmed HIV test). MSM who were firstly identified as HIV positive through HIVST and HIVFBT were compared. Chi-square or Fisher’s exact test was used to explore any association between both groups and their subgroups.

Results

In total, 124 MSM HIV cases were identified from 2017 to 2021 in Zhuhai, China, including 60 identified through HIVST and 64 through HIVFBT. Participants in the HIVST group were younger (≤30 years, 76.7% vs. 46.9%), were better educated (>high school, 61.7% vs. 39.1%), and had higher viral load (≥1,000 copies/ml, 71.7% vs. 50.0%) than MSM cases identified through HIVFBT. The proportion of early HIV infection in the HIVST group was higher than in the HIVFBT group, identified using four recent infection testing algorithms (RITAs) (RITA 1, 46.7% vs. 25.0%; RITA 2, 43.3% vs. 20.3%; RITA 3, 30.0% vs. 14.1%; RITA 4, 26.7% vs. 10.9%; all p < 0.05).

Conclusions

The study showed that HIVST has better HIV early detection among MSM and that recent HIV infection cases mainly occur in younger and better-educated MSM. Compared with HIVFBT, HIVST is more accessible to the most at-risk population on time and tends to identify the case early. Further implementation studies are needed to fill the knowledge gap on this medical service model among MSM and other target populations.

Evaluation of SAMBA II: A Qualitative and Semiquantitative HIV Point-of-Care Nucleic Acid Test

BACKGROUND

Point-of-care (POC) nucleic acid tests (NATs) have potential to diagnose acute HIV infection and monitor persons taking pre-exposure prophylaxis or antiretroviral therapy (ART). POC NATs have not yet been evaluated in the US.

METHODS

From June 2018-March 2019, we conducted a cross-sectional evaluation of the Simple Amplification-Based Assay version II (SAMBA II) POC NAT. People with HIV (PWH) and persons testing for HIV were tested with the SAMBA II qualitative (Qual) whole blood (WB) test. From April-September 2019, the Qual test was used on persons who were ART-naive, and SAMBA II Semi-quantitative (Semi-Q) WB was used with ART-experienced PWH. Both were performed on unprocessed venipuncture (VP) and, when indicated by protocol, fingerstick (FS) WB and plasma. SAMBA results were compared with Abbott RealTime HIV-1 polymerase chain reaction results on plasma. We calculated sensitivity, specificity, and concordance between tests.

RESULTS

SAMBA was used in 330 visits among 280 participants: 202 (61.2%) visits from PWH, and 128 (38.8%) from HIV-negative persons. Qual test sensitivity with ART-naive participants was 91.4% [32/35, 95% confidence interval (CI): 77.6% to 97.0%] using VP WB and 100% (27/27, 95% CI: 87.5% to 100%) using FS WB. Specificity was 100% using both specimen types. Concordance between the gold standard and Semi-Q at 1000 copies/mL among PWH on ART was 97.7% (86/88, 95% CI: 92.1% to 99.4%) and 100% (30/30, 95% CI: 88.7% to 100%) using VP and FS WB, respectively.

CONCLUSIONS

The SAMBA II POC NATs showed high sensitivity, specificity, and concordance with the gold standard assay, indicating its potential use in diagnostics and monitoring. Future work will evaluate POC NAT implementation in the US.

Effective strategies to promote HIV self-testing for men who have sex with men: Evidence from a mathematical model

BACKGROUND

HIV testing is the gateway to HIV treatment and prevention. HIV self-testing (HIVST) has potential to increase testing; however, the potential population-level impact of HIVST on the HIV epidemic and the best strategies for promoting HIVST are unknown. Our aim is to inform public health approaches for promoting HIVST as part of a comprehensive strategy to reduce HIV incidence.

METHODS

Stochastic network-based HIV transmission models were used to estimate how different HIVST strategies would affect HIV incidence in Seattle and Atlanta over 10 years. We included four types of HIV testers and implemented nine replacement and eleven supplementation strategies for HIVST.

RESULTS

Replacement of clinic-based tests with HIVST increased HIV incidence in Seattle and Atlanta. The benefits of supplementary strategies depended on the tester type using HIVST. Targeting non-testers averted the highest number of cases per test. In Seattle 2.2 (95%SI=-77, 100.4) and 4.7 (95%SI=-35.7, 60.1) infections were averted per 1000 HIVST when non-testers used HIVST once or twice per year respectively. In Atlanta the comparable rates were 8.0 (95%SI=-60.3 to 77.7) and 6.7 (95%SI=-37.7, 41.0). Paradoxically, increasing testing among risk-based testers using HIVST increased incidence.

CONCLUSIONS

The population-level impact of HIVST depends on who is reached with HIVST, how kits are used, and by characteristics of the underlying epidemic and HIV care infrastructure. Targeted HIVST can be an effective component of a comprehensive HIV testing strategy. More work is needed to understand how to identify and target non-testers for self-testing implementation.

Effectiveness of HIV Self-testing on Regular HIV Testing Among Ever-Tested Men Who Have Sex Men in China: A Pragmatic Randomized Controlled Trial

The purpose of this study was to demonstrate the effectiveness of HIV self-testing (HIVST) on promoting regular HIV testing, which defined as having uptake HIV testing every three to 6 months, among men who have sex with men (MSM) in Guangzhou, China. 491 ever-tested MSM were recruited from a community-based HIV clinic and randomly assigned into either intervention arm that provided text message plus HIVST service (n = 250) or standard of care arm (n = 241) being a text message promoting HIV testing every 3 months. Overall, 73.7% (330/448) of the participants had uptake HIV testing, and 27.7% (124/448) of them reported ever used of an HIV self-test during study period. HIVST significantly increased regularly HIV testing among participants in the intervention arm compared with standard of care arm (77.4% vs 69.5%). HIVST as a supplement to the existing facility-based testing services is promising in promoting regular HIV testing among MSM in China. Trial registration number: ChiCTR1800016811.

Rapid Testing Algorithm Performance in a Low-Prevalence Environment

BACKGROUND

The performance of a statewide HIV rapid test algorithm (RTA) in a low-prevalence setting (0.71%) was examined for 3 years.

METHODS

An initial rapid screening by HIV-1/2 Ag/Ab Combo test (RT#1) with Ab verification using a second, different rapid test (RT#2) was conducted. Clinic referral was immediate for antigen-only-positive screens. Antibody-positive screens were confirmed by RT#2. Specimens were collected following discordant RTA results (initially Ab-POS by RT#1, but negative on RT#2) and tested in accordance with the current Centers for Disease Control and Prevention/Association of Public Health Laboratories-based HIV diagnostic algorithm supplemented by a quantitative viral load whenever possible.

RESULTS

Of 310,785 tests performed, 2400 preliminary positive screens were identified; 2191 (91.8%) confirmed by RT#2. Of 13 Determine Combo AG-POS results identified, only 1 confirmed positive. Of the remaining 196 discordant results, 182 (92.9%) were uninfected, including 13 with AG-POS/AB-POS results. Of 14 true positives (7.1%) identified after discordant RTA results, the average quantitative HIV-1 viral load was 277,385 copies/mL, but 5 (35.7%) of 14 had viral loads <1000 copies/mL. Among the 2191 "presumptive positive" by RTA, 3 false-positive (FP) RTAs were reported (both rapid tests having positive results, while the HIV-1/2 Ag/Ab assay and quantitative HIV-1 viral load showed negative results).

CONCLUSIONS

The RTA was effective in predicting true-positive HIV test results and facilitating linkage to care. Discordant results were infrequent. Fingerstick DC Ag detection identified a single early infection. Many discordant cases that were subsequently positive were associated with viral loads <1000 copies/mL.

Unique Needs for the Implementation of Emergency Department Human Immunodeficiency Virus Screening in Adolescents

BACKGROUND

The Centers for Disease Control and Prevention (CDC) recommend universal human immunodeficiency virus (HIV) screening starting at 13 years, which has been implemented in many general U.S. emergency departments (EDs) but infrequently in pediatric EDs. We aimed to 1) implement a pilot of routine adolescent HIV screening in a pediatric ED and 2) determine the unique barriers to CDC-recommended screening in this region of high HIV prevalence.

METHODS

This was a prospective 4-month implementation of a routine HIV screening pilot in a convenience sample of adolescents 13 to 18 years at a single pediatric ED, based on study personnel availability. Serum-based fourth-generation HIV testing was run through a central laboratory. Parents were allowed to remain in the room for HIV counseling and testing. Data were collected regarding patient characteristics and HIV testing quality metrics. Comparisons were made using chi-square and Fisher's exact tests. Regression analysis was performed to assess for an association between parent presence at the time of enrollment and adolescent decision to participate in HIV screening.

RESULTS

Over 4 months, 344 of 806 adolescents approached consented to HIV screening (57% female, mean ± SD = 15.1 ± 1.6 years). Adolescents with HIV screening were more likely to be older than those who declined (p = 0.025). Other blood tests were collected with the HIV sample for 21% of adolescents; mean time to result was 105 minutes (interquartile range = 69 to 123) and 79% were discharged before the result was available. Having a parent present for enrollment was not associated with adolescent participation (adjusted odds ratio = 1.07, 95% CI = 0.67 to 1.70). Barriers to testing included: fear of needlestick, time to results, cost, and staff availability. One of 344 tests was positive in a young adolescent with Stage 1 HIV.

CONCLUSIONS

Routine HIV screening in adolescents was able to be implemented in this pediatric ED and led to the identification of early infection in a young adolescent who would have otherwise been undetected at this stage of disease. Addressing the unique barriers to adolescent HIV screening is critical in high-prevalence regions and may lead to earlier diagnosis and treatment in this vulnerable population.

Performance evaluation of four point-of-care HIV tests using unprocessed specimens

BACKGROUND

The performance of recently approved point-of-care (POC) HIV tests should be assessed using unprocessed specimens.

OBJECTIVE

To evaluate the sensitivity and specificity of four POC HIV tests using whole blood (WB) and two using oral fluid (OF) among persons recruited from health clinics in Seattle, Washington, during September 2015-September 2017.

STUDY DESIGN

Participants were tested with the POC tests, additional plasma and serum were collected for laboratory testing, and participant- reported use of antiretroviral therapy (ART) or pre-exposure prophylaxis (PrEP) was recorded. Participants testing negative on all tests could reenroll every 90 days. Specimens from persons previously diagnosed with HIV infection as well as from those who were newly diagnosed during the study were included in the sensitivity estimate. Sensitivity and specificity were calculated based on HIV status determined by laboratory testing.

RESULTS

Of 1,256 visits, 179 were from persons with HIV infection; 120 of these were taking ART. Among 1,077 visits from participants not diagnosed with HIV, PrEP use was reported at 155 (14.4%) visits. Sensitivity was similar among POC WB tests (95.53%-97.21%; p>0.05). Among participants on ART, sensitivity was lower for the same test performed on OF compared to WB (p<0.003). Specificity was high for all tests (99.44%- 100.00%); we did not detect specificity differences with PrEP use.

CONCLUSIONS

These POC tests displayed relatively high sensitivity and specificity using unprocessed specimens, suggesting their effectiveness in identifying HIV infections whenever laboratory-based testing is not feasible. Nonetheless, clients with recent risk should retest to rule out the possibility of a false-negative result.

Prospective Evaluation of HIV Testing Technologies in a Clinical Setting: Protocol for Project DETECT

BACKGROUND

HIV testing guidelines provided by the Centers for Disease Control and Prevention (CDC) are continually changing to reflect advancements in new testing technology. Evaluation of existing and new point-of-care (POC) HIV tests is crucial to inform testing guidelines and provide information to clinicians and other HIV test providers. Characterizing the performance of POC HIV tests using unprocessed specimens can provide estimates for the window period of detection, or the time from HIV acquisition to test positivity, which allows clinicians and other HIV providers to select the appropriate POC HIV tests for persons who may be recently infected with HIV.

OBJECTIVE

This paper describes the protocols and procedures used to evaluate the performance of the newest POC tests and determine their sensitivity during early HIV infection.

METHODS

Project DETECT is a CDC-funded study that is evaluating POC HIV test performance. Part 1 is a cross-sectional, retrospective study comparing behavioral characteristics and HIV prevalence of the overall population of the Public Health-Seattle & King County (PHSKC) Sexually Transmitted Disease (STD) Clinic to Project DETECT participants enrolled in part 2. Part 2 is a cross-sectional, prospective study evaluating POC HIV tests in real time using unprocessed whole blood and oral fluid specimens. A POC nucleic acid test (NAT) was added to the panel of HIV tests in June 2018. Part 3 is a longitudinal, prospective study evaluating seroconversion sensitivity of POC HIV tests through serial follow-up testing. For comparison, HIV-1 RNA and HIV-1/HIV-2 antigen/antibody tests are also performed for participants enrolled in part 2 or 3. A behavioral survey that collects information about demographics, history of HIV testing, STD history, symptoms of acute HIV infection, substance use, sexual behaviors in the aggregate and with recent partners, and use of pre-exposure prophylaxis and antiretroviral therapy is completed at each part 2 or 3 visit.

RESULTS

Between September 2015 and March 2019, there were 14,990 Project DETECT-eligible visits (part 1) to the PHSKC STD Clinic resulting in 1819 part 2 Project DETECT study visits. The longitudinal study within Project DETECT (part 3) enrolled 27 participants with discordant POC test results from their part 2 visit, and 10 (37%) were followed until they had fully seroconverted with concordant positive POC test results. Behavioral survey data and HIV test results, sensitivity, and specificity will be presented elsewhere.

CONCLUSIONS

Studies such as Project DETECT are critical for evaluating POC HIV test devices as well as describing characteristics of persons at risk for HIV acquisition in the United States. HIV tests in development, including POC NATs, will provide new opportunities for HIV testing programs.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR1-10.2196/16332.

Diagnostic Performances of Three Rapid Diagnostic Tests for Detecting HIV Infections in Mali

Diagnosis of HIV infections in resource-limited countries like Mali is based on Rapid Diagnostic Tests (RDTs). The RDTs are diagnostic assays designed for use at the Point-Of-Care (POC), which is quick, cost-effective and easy to perform. However, in these countries, the tests are commonly used without any initial evaluation or monitoring of their performance despite high levels of HIV strain diversity and rapid evolution of the virus. In this study, the reliability and accuracy of HIV RDTs (Determine^™, Multispot^™, SD Bioline^™) used in Mali, where HIV-1 and HIV-2 co-exist, were evaluated from August 2004 to November 2017. A total of 1303 samples from new HIV-suspect patients in Bamako were tested for HIV-1 and HIV-2 using the RDT Determine^™, followed by ELISA and Western Blot (WB). The Determine^™ test showed a robust diagnostic sensitivity of 98.7% [CI 95: 97.59-99.37] and a diagnostic specificity of 99.2% [CI 95: 98.22-99.67]. The Multispot^™ assay showed a diagnostic sensitivity of 98.77% [CI 95: 97.59-99.37] and a diagnostic specificity of 99.2% [CI 95: 98.22-99.67]. The diagnostic sensitivity and specificity of SD Bioline^™ HIV-1/2 were 100% [CI 95:72.25-100] and 88.89% [CI 95: 56.50- 98.71], respectively. These data indicate excellent performance for HIV RDTs in Mali and we recommend the use of Determine^™ HIV-1/2 for HIV screening and Multispot™ for discriminating HIV-2 from HIV-1 infections.

HIV Self-Testing Increases HIV Testing Frequency in High-Risk Men Who Have Sex With Men: A Randomized Controlled Trial

BACKGROUND

Self-testing may increase HIV testing and decrease the time people with HIV are unaware of their status, but there is concern that absence of counseling may result in increased HIV risk.

SETTING

Seattle, Washington.

METHODS

We randomly assigned 230 high-risk HIV-negative men who have sex with men to have access to oral fluid HIV self-tests at no cost versus testing as usual for 15 months. The primary outcome was self-reported number of HIV tests during follow-up. To evaluate self-testing's impact on sexual behavior, we compared the following between arms: non-HIV-concordant condomless anal intercourse and number of male condomless anal intercourse partners in the last 3 months (measured at 9 and 15 months) and diagnosis with a bacterial sexually transmitted infection (STI: early syphilis, gonorrhea, and chlamydial infection) at the final study visit (15 months). A post hoc analysis compared the number of STI tests reported during follow-up.

RESULTS

Men randomized to self-testing reported significantly more HIV tests during follow-up (mean = 5.3, 95% confidence interval = 4.7 to 6.0) than those randomized to testing as usual (3.6, 3.2 to 4.0; P < 0.0001), representing an average increase of 1.7 tests per participant over 15 months. Men randomized to self-testing reported using an average of 3.9 self-tests. Self-testing was noninferior with respect to all markers of HIV risk. Men in the self-testing arm reported significantly fewer STI tests during follow-up (mean = 2.3, 95% confidence interval = 1.9 to 2.7) than men in the control arm (3.2, 2.8 to 3.6; P = 0.0038).

CONCLUSIONS

Access to free HIV self-testing increased testing frequency among high-risk men who have sex with men and did not impact sexual behavior or STI acquisition.

Pre-exposure prophylaxis awareness and interest among participants in a medications for addiction treatment program in a unified jail and prison setting in Rhode Island

People who are incarcerated are at increased risk for HIV (human immunodeficiency virus) acquisition upon release, and one possible intervention for prevention is the use of pre-exposure prophylaxis (PrEP) upon release. The present study assessed HIV risk perceptions as well as PrEP awareness and interest among 39 people who were incarcerated and enrolled in a structured Medication for Addiction Treatment (MAT) program at the Rhode Island Department of Corrections using semi-structured, qualitative interviews. Analysis was conducted using a generalized, inductive method in NVivo 12. While PrEP awareness was low across the study sample, some participants were interested in PrEP uptake or learning more about PrEP after they were provided with an overview of it. PrEP interest strongly related to current perceived HIV risk. Potential barriers included side effects, adherence, and reluctance to take medications in general. MAT programs for people who are criminal justice (CJ) involved may serve as useful linkage spaces to PrEP information, access, and retention.

Comparisons of New HIV Rapid Test Kit Performance

The development of rapid point-of-care tests for HIV infection has greatly reduced the problem of failure to return for test results. Test manufacturers are now developing test kits that can test for two or even three diseases at the same time, multiple-disease test kits. This study reports on the sensitivity and specificity of HIV tests when included on multi-disease test kits. 1029 participants were recruited from 2011 to 2014. HIV test kit sensitivities ranged from 91.1 to 100%, and the HIV test kit specificities from 99.5 to 100%. The two HIV kits which used oral fluid instead of blood performed well.

Plasmonic gold chips for the diagnosis of Toxoplasma gondii, CMV, and rubella infections using saliva with serum detection precision

Sampling the blood compartment by an invasive procedure such as phlebotomy is the most common approach used for diagnostic purposes. However, phlebotomy has several drawbacks including pain, vasovagal reactions, and anxiety. Therefore, alternative approaches should be tested to minimize patient's discomfort. Saliva is a reasonable compartment; when obtained, it generates little or no anxiety. We setup a multiplexed serology assay for detection of Toxoplasma gondii IgG and IgM, rubella IgG, and CMV IgG, in serum, whole blood, and saliva using novel plasmonic gold (pGOLD) chips. pGOLD test results in serum, whole blood, and saliva were compared with commercial kits test results in serum. One hundred twenty serum/saliva sets (Lyon) and 28 serum/whole blood/saliva sets (Nice) from France were tested. In serum and whole blood, sensitivity and specificity of multiplex T. gondii, CMV, and rubella IgG were 100% in pGOLD when compared to commercial test results in serum. In saliva, sensitivity and specificity for T. gondii and rubella IgG were 100%, and for CMV IgG, sensitivity and specificity were 92.9% and 100%, respectively, when compared to commercial test results in serum. We were also able to detect T. gondii IgM in saliva with sensitivity and specificity of 100% and 95.4%, respectively, when compared to serum test results. Serological testing by multiplex pGOLD assay for T. gondii, rubella, and CMV in saliva is reliable and likely to be more acceptable for systematic screening of pregnant women, newborn, and immunocompromised patients.

Repeated False-Positive HIV Test Results in a Patient Taking HIV Pre-Exposure Prophylaxis

Regular HIV testing is required to ensure the safety of HIV pre-exposure prophylaxis (PrEP). We describe and discuss a series of false-positive HIV test results from an individual receiving PrEP. The expansion of PrEP will likely result in greater numbers of false-positive test results that may pose challenges for interpretation.

No Time to Delay! Fiebig Stages and Referral in Acute HIV infection: Seattle Primary Infection Program Experience

There has been increasing recognition of the importance of diagnosing individuals during the earliest stages of human immunodeficiency virus (HIV) infection. Sera from individuals referred to a primary HIV infection research program were screened using the IgG-sensitive Vironostika HIV-1 Microelisa System, IgG/IgM-sensitive GS HIV-1/HIV-2 Plus O antibody enzyme immunoassay (EIA), or Abbott ARCHITECT HIV antigen (Ag)/antibody (Ab) Combo assay and confirmed by the Bio-Rad Multispot and Western blot. A subset of participants was co-enrolled in a study designed to compare the ability of point-of-care tests to detect early infection. We calculated time within primary infection laboratory stages using actual observed transitions and with an expectation-maximization algorithm. Three hundred and sixty participants contributed data to this analysis. Of 123 persons referred with EIA-negative/RNA-positive test results (Fiebig stage I-II) or for concern for symptoms, 24 (20%) were still in stages I-II, and 99 (80%) were in stages III or later at their screening visit. Participants were estimated to spend a median of 13.5 days in stages I and II, 2.3 days in stage III, and 7.8 days in stage IV. OraQuick performed on oral fluids detected 53% of 17 participants in stage V. The durations of stages we observed are consistent with previous publications. Most persons referred for research no longer had acute infection at their first visit. Programs wishing to identify persons in the very earliest stages of infection need to expedite referrals or develop targeted screening programs.

Development of an Agent-Based Model to Investigate the Impact of HIV Self-Testing Programs on Men Who Have Sex With Men in Atlanta and Seattle

BACKGROUND

In the United States HIV epidemic, men who have sex with men (MSM) remain the most profoundly affected group. Prevention science is increasingly being organized around HIV testing as a launch point into an HIV prevention continuum for MSM who are not living with HIV and into an HIV care continuum for MSM who are living with HIV. An increasing HIV testing frequency among MSM might decrease future HIV infections by linking men who are living with HIV to antiretroviral care, resulting in viral suppression. Distributing HIV self-test (HIVST) kits is a strategy aimed at increasing HIV testing. Our previous modeling work suggests that the impact of HIV self-tests on transmission dynamics will depend not only on the frequency of tests and testers' behaviors but also on the epidemiological and testing characteristics of the population.

OBJECTIVE

The objective of our study was to develop an agent-based model to inform public health strategies for promoting safe and effective HIV self-tests to decrease the HIV incidence among MSM in Atlanta, GA, and Seattle, WA, cities representing profoundly different epidemiological settings.

METHODS

We adapted and extended a network- and agent-based stochastic simulation model of HIV transmission dynamics that was developed and parameterized to investigate racial disparities in HIV prevalence among MSM in Atlanta. The extension comprised several activities: adding a new set of model parameters for Seattle MSM; adding new parameters for tester types (ie, regular, risk-based, opportunistic-only, or never testers); adding parameters for simplified pre-exposure prophylaxis uptake following negative results for HIV tests; and developing a conceptual framework for the ways in which the provision of HIV self-tests might change testing behaviors. We derived city-specific parameters from previous cohort and cross-sectional studies on MSM in Atlanta and Seattle. Each simulated population comprised 10,000 MSM and targeted HIV prevalences are equivalent to 28% and 11% in Atlanta and Seattle, respectively.

RESULTS

Previous studies provided sufficient data to estimate the model parameters representing nuanced HIV testing patterns and HIV self-test distribution. We calibrated the models to simulate the epidemics representing Atlanta and Seattle, including matching the expected stable HIV prevalence. The revised model facilitated the estimation of changes in 10-year HIV incidence based on counterfactual scenarios of HIV self-test distribution strategies and their impact on testing behaviors.

CONCLUSIONS

We demonstrated that the extension of an existing agent-based HIV transmission model was sufficient to simulate the HIV epidemics among MSM in Atlanta and Seattle, to accommodate a more nuanced depiction of HIV testing behaviors than previous models, and to serve as a platform to investigate how HIV self-tests might impact testing and HIV transmission patterns among MSM in Atlanta and Seattle. In our future studies, we will use the model to test how different HIV self-test distribution strategies might affect HIV incidence among MSM.

The fourth generation AlereTM HIV Combo rapid test improves detection of acute infection in MTN-003 (VOICE) samples

BACKGROUND

Early and accurate detection of HIV is crucial when using pre-exposure prophylaxis (PrEP) for HIV prevention to avoid PrEP initiation in acutely infected individuals and to minimize the risk of drug resistance in individuals with breakthrough infection.

OBJECTIVE

To determine if fourth-generation antigen/antibody (Ag/Ab) rapid diagnostic tests (RDT) would have detected HIV infection earlier than the third-generation RDT used in MTN-003 (VOICE).

STUDY DESIGN

5029 VOICE participants were evaluated with third-generation Alere Determine™ HIV-1/2, OraQuick ADVANCE^® Rapid HIV-1/2, Uni-Gold™ Recombigen^® HIV-1/2 and Bio-Rad GS HIV-1/2+O EIA; and fourth-generation Alere Determine™ HIV-1/2 Ag/Ab Combo, Conformité Européene (CE)-Marked Alere™ HIV Combo and Bio-Rad HIV Combo Ag/Ab EIA. Multispot^®, GS HIV-1 Western Blot (WB) and Geenius™ (Bio-Rad) were also evaluated.

RESULTS

Of 57 antibody-negative pre-seroconversion plasma samples with HIV RNA >20 copies/mL identified, 16 (28%) were reactive by CE-Marked Alere™ HIV Combo (1 Ab; 9 Ag; 6 Ag/Ab reactive) and 4 (7%) by Alere Determine™ HIV-1/2 Ag/Ab Combo (2 Ab; 2 Ag; 0 Ag/Ab reactive) (p=0.0005). Multispot^® confirmed only 1 of 16 acute infections while WB and Geenius™ confirmed none. GS HIV Combo Ag/Ab EIA identified 27 of 57 (47%) pre-seroconversion RNA-positive samples.

CONCLUSION

In VOICE, 28% of infections missed by current third-generation RDT would have been identified with the use of CE-Marked Alere™ HIV Combo. Geenius™, Multispot^® and WB were all insensitive (<10%) in confirming infections detected by fourth-generation assays. An improved diagnostic algorithm that includes a fourth-generation RDT with HIV RNA testing will be essential for efficiently identifying seroconverters on PrEP.

Performance evaluation of the FDA-approved Determine™ HIV-1/2 Ag/Ab Combo assay using plasma and whole blood specimens

BACKGROUND

The Determine™ HIV-1/2 Ag/Ab Combo (DC) rapid test can identify HIV-1 infection earlier than rapid antibody-only tests in plasma specimens.

OBJECTIVES

We compared the performance of DC with a laboratory-based antigen/antibody (Ag/Ab) combo assay in plasma and evaluated antigen reactivity in whole blood specimens.

STUDY DESIGN

We tested by DC 508 plasma specimens collected in a prospective study and 107 sequential plasma and simulated whole blood specimens from 20 seroconversion panels. Previous results using the ARCHITECT (ARC) Ag/Ab combo assay were compared to DC results. In seroconversion panels, the days from the first HIV1 RNA-positive test to first DC-reactive in plasma and whole blood was compared. McNemar's and Wilcoxon signed rank tests were used for statistical analysis.

RESULTS

Of 415 HIV-positive samples, ARC detected 396 (95.4%) and DC 337 (81.2%) (p<0.0001). DC was reactive in 50.0% of ARC-reactive/MS-negative, 78.6% of ARC-reactive/MS-indeterminate, and 99.6% of ARC-reactive/MS-HIV-1-positive or -undifferentiated specimens. DC antigen reactivity was higher among ARC-reactive/MS-negative than MS-indeterminate samples. In 20 HIV-1 seroconversion panels, there was a significant difference between DC reactivity in plasma (91.1%) and whole blood (56.4%) (p<0.0001). DC with whole blood showed a significant delay in reactivity compared to plasma (p=0.008).

CONCLUSIONS

In plasma, DC was significantly less sensitive than an instrumented laboratory-based Ag/Ab combo assay. DC in plasma was significantly more sensitive compared to whole blood in early HIV-1 infections. With the U.S. laboratory-based diagnostic algorithm, DC as the first step would likely miss a high proportion of HIV-1 infections in early stages of seroconversion.

Detection of HIV RNA in dried blood spots and oral fluids

: We evaluated detection of HIV-1 RNA from dried blood spots (DBS) and oral fluid specimens. Between February 2010 and August 2014, HIV-1 was newly diagnosed in eight (2.6%) study participants who had median blood HIV-1 RNA of 61 500 copies/ml (interquartile range 7500-146 000). RNA was detected in seven (87.5%) DBS and three (37.5%) oral fluid swabs but was not detected in either specimen from one participant. DBS may be a reasonable specimen collection method to detect acute infection.

Implementation of Point-of-Care Diagnostics in Rural Primary Healthcare Clinics in South Africa: Perspectives of Key Stakeholders

Introduction: Key stakeholders’ involvement is crucial to the sustainability of quality point-of-care (POC) diagnostics services in low-and-middle income countries. The aim of this study was to explore key stakeholder perceptions on the implementation of POC diagnostics in rural primary healthcare (PHC) clinics in South Africa. Method: We conducted a qualitative study encompassing in-depth interviews with multiple key stakeholders of POC diagnostic services for rural and resource-limited PHC clinics. Interviews were digitally recorded and transcribed verbatim prior to thematic content analysis. Thematic content analysis was conducted using themes guided by the World Health Organisation (WHO) quality-ASSURED (Affordable, Sensitive, Specific, User friendly, Rapid and to enable treatment at first visit and Robust, Equipment free and Delivered to those who need it) criteria for POC diagnostic services in resource-limited settings. Results: 11 key stakeholders participated in the study. All stakeholders perceived the main advantage of POC diagnostics as enabling access to healthcare for rural patients. Stakeholders perceived the current POC diagnostic services to have an ability to meet patients’ needs, but recommended further improvement of the following areas: research on cost-effectiveness; improved quality management systems; development of affordable POC diagnostic and clinic-based monitoring and evaluation. Conclusions: Key stakeholders of POC diagnostics in rural PHC clinics in South Africa highlighted the need to assess affordability and ensure quality assurance of current services before adopting new POC diagnostics and scaling up current POC diagnostics.