Scaling up COVID-19 rapid antigen tests: promises and challenges.

WHO recommends a minimum of 80% sensitivity and 97% specificity for antigen-detection rapid diagnostic tests (Ag-RDTs), which can be used for patients with symptoms consistent with COVID-19. However, after the acute phase when viral load decreases, use of Ag-RDTs might lead to high rates of false negatives, suggesting that the tests should be replaced by a combination of molecular and serological tests. When the likelihood of having COVID-19 is low, such as for asymptomatic individuals in low prevalence settings, for travel, return to schools, workplaces, and mass gatherings, Ag-RDTs with high negative predictive values can be used with confidence to rule out infection. For those who test positive in low prevalence settings, the high false positive rate means that mitigation strategies, such as molecular testing to confirm positive results, are needed. Ag-RDTs, when used appropriately, are promising tools for scaling up testing and ensuring that patient management and public health measures can be implemented without delay.

REASSURED diagnostics to inform disease control strategies, strengthen health systems and improve patient outcomes.

Lack of access to quality diagnostics remains a major contributor to health burden in resource-limited settings. It has been more than 10 years since ASSURED (affordable, sensitive, specific, user-friendly, rapid, equipment-free, delivered) was coined to describe the ideal test to meet the needs of the developing world. Since its initial publication, technological innovations have led to the development of diagnostics that address the ASSURED criteria, but challenges remain. From this perspective, we assess factors contributing to the success and failure of ASSURED diagnostics, lessons learnt in the implementation of ASSURED tests over the past decade, and highlight additional conditions that should be considered in addressing point-of-care needs. With rapid advances in digital technology and mobile health (m-health), future diagnostics should incorporate these elements to give us REASSURED diagnostic systems that can inform disease control strategies in real-time, strengthen the efficiency of health care systems and improve patient outcomes.

The impact of digital technologies on point-of-care diagnostics in resource-limited settings.

INTRODUCTION: Simple, rapid tests that can be used at the point-of-care (POC) can improve access to diagnostic services and overall patient management in resource-limited settings where laboratory infrastructure is limited. Implementation of POC tests places tremendous strain on already fragile health systems as the demand for training, supply management and quality assurance are amplified. Digital health has a major role to play in ensuring effective delivery and management of POC testing services. Area covered: The ability to digitise laboratory and POC platforms, including lateral flow rapid diagnostic test results, can standardize the interpretation of results and allows data to be linked to proficiency testing to ensure testing quality, reducing interpretation and transcription errors. Remote monitoring of POC instrument functionality and utilization through connectivity, allows programs to optimize instrument placement, algorithm adoption and supply management. Alerts can be built into the system to raise alarm at unusual trends such as outbreaks. Expert commentary: Digital technology has had a powerful impact on POC testing in resource limited settings. Technology, markets, and medical devices have matured to enable connected diagnostics to become a useful tool for epidemiology, patient care and tracking, research, and antimicrobial resistance and outbreak surveillance. However, to unlock this potential, digital tools must first add value at the point of patient care. The global health community need to propose models for protecting intellectual property to foster innovation and for safeguarding data confidentiality.

Diagnostic accuracy of tests to detect hepatitis B surface antigen: a systematic review of the literature and meta-analysis.

BACKGROUND: Chronic Hepatitis B Virus (HBV) infection is characterised by the persistence of hepatitis B surface antigen (HBsAg). Expanding HBV diagnosis and treatment programmes into low resource settings will require high quality but inexpensive rapid diagnostic tests (RDTs) in addition to laboratory-based enzyme immunoassays (EIAs) to detect HBsAg. The purpose of this review is to assess the clinical accuracy of available diagnostic tests to detect HBsAg to inform recommendations on testing strategies in 2017 WHO hepatitis testing guidelines. METHODS: The systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines using 9 databases. Two reviewers independently extracted data according to a pre-specified plan and evaluated study quality. Meta-analysis was performed. HBsAg diagnostic accuracy of rapid diagnostic tests (RDTs) was compared to enzyme immunoassay (EIA) and nucleic-acid test (NAT) reference standards. Subanalyses were performed to determine accuracy among brands, HIV-status and specimen type. RESULTS: Of the 40 studies that met the inclusion criteria, 33 compared RDTs and/or EIAs against EIAs and 7 against NATs as reference standards. Thirty studies assessed diagnostic accuracy of 33 brands of RDTs in 23,716 individuals from 23 countries using EIA as the reference standard. The pooled sensitivity and specificity were 90.0% (95% CI: 89.1, 90.8) and 99.5% (95% CI: 99.4, 99.5) respectively, but accuracy varied widely among brands. Accuracy did not differ significantly whether serum, plasma, venous or capillary whole blood was used. Pooled sensitivity of RDTs in 5 studies of HIV-positive persons was lower at 72.3% (95% CI: 67.9, 76.4) compared to that in HIV-negative persons, but specificity remained high. Five studies evaluated 8 EIAs against a chemiluminescence immunoassay reference standard with a pooled sensitivity and specificity of 88.9% (95% CI: 87.0, 90.6) and 98.4% (95% CI: 97.8, 98.8), respectively. Accuracy of both RDTs and EIAs using a NAT reference were generally lower, especially amongst HIV-positive cohorts. CONCLUSIONS: HBsAg RDTs have good sensitivity and excellent specificity compared to laboratory immunoassays as a reference standard. Sensitivity of HBsAg RDTs may be lower in HIV infected individuals.

The future of viral hepatitis testing: innovations in testing technologies and approaches.

A large burden of undiagnosed hepatitis virus cases remains globally. Despite the 257 million people living with chronic hepatitis B virus infection, and 71 million with chronic viraemic HCV infection, most people with hepatitis remain unaware of their infection. Advances in rapid detection technology have created new opportunities for enhancing access to testing and care, as well as monitoring of treatment. This article examines a range of other technological innovations that can be leveraged to provide more affordable and simplified approaches to testing for HBV and HCV infection and monitoring of treatment response. These include improved access to testing through alternative sampling methods (use of dried blood spots, oral fluids, self-testing) and combination rapid diagnostic tests for detection of HIV, HBV and HCV infection; more affordable options for confirmation of virological infection (HBV DNA and HCV RNA) such as point-of-care molecular assays, HCV core antigen and multi-disease polyvalent molecular platforms that make use of existing centralised laboratory based or decentralised TB and HIV instrumentation for viral hepatitis testing; and finally health system improvements such as integration of laboratory services for procurement and sample transportation and enhanced data connectivity to support quality assurance and supply chain management.

Re-imagining the future of diagnosis of Neglected Tropical Diseases.

Neglected Tropical Diseases (NTDs) affect an estimated 1 billion people in 149 countries. The World Health Organization (WHO) prioritised 17 NTDs for control and elimination by 2020 and defined a Road Map to help countries reach these goals. Improved diagnostics for NTDs are essential for guiding treatment strategies at different thresholds of control, interruption of transmission, elimination and post-elimination surveillance. While substantial progress has been made in the last decade with chemotherapy, the same cannot be said of diagnostics, largely due to the perceived lack of a commercially viable market for NTD diagnostics. New sample in-answer out nucleic acid amplification technologies that can be performed at the point-of-care offer improved performance over current technologies and the potential to test for multiple pathogens using a single specimen. Finding commonalities for different NTDs in terms of geographic overlap, sentinel populations and treatment strategy will allow NTD programs to leverage these innovations to build cost-effective multiplex surveillance platforms. Connectivity solutions linking data from diagnostic laboratories and POC test readers/devices provide opportunities for automated surveillance systems to make health systems more efficient, improving patient outcomes and assessing impact of interventions in real time. New models of public-private product development partnerships are critical in leveraging diagnostic innovation in other priority area for better diagnosis, control and elimination of NTDs.

Implementation science: the laboratory as a command centre.

PURPOSE OF REVIEW: Recent advances in point-of-care technologies to ensure universal access to affordable quality-assured diagnostics have the potential to transform patient management, surveillance programmes, and control of infectious diseases. Decentralization of testing can put tremendous stresses on fragile health systems if the laboratory is not involved in the planning, introduction, and scale-up strategies. RECENT FINDINGS: The impact of investments in novel technologies can only be realized if these tests are evaluated, adopted, and scaled up within the healthcare system with appropriate planning and understanding of the local contexts in which these technologies will be used. SUMMARY: In this digital age, the laboratory needs to take on the role of the Command Centre for technology introduction and implementation. Implementation science is needed to understand the political, cultural, economic, and behavioural context for technology introduction. The new paradigm should include: building a comprehensive system of laboratories and point-of-care testing sites to provide quality-assured diagnostic services with good laboratory-clinic interface to build trust in test results and linkage to care; building and coordinating a comprehensive national surveillance and communication system for disease control and global health emergencies; conducting research to monitor the impact of new tools and interventions on improving patient care.

Corrigendum: Assuring the quality of diagnostic testing: the future is now.

[This corrects the article DOI: 10.4102/ajlm.v5i2.558.].

Access and Quality of HIV-Related Point-of-Care Diagnostic Testing in Global Health Programs.

Access to point-of-care testing (POCT) improves patient care, especially in resource-limited settings where laboratory infrastructure is poor and the bulk of the population lives in rural settings. However, because of challenges in rolling out the technology and weak quality assurance measures, the promise of human immunodeficiency virus (HIV)-related POCT in resource-limited settings has not been fully exploited to improve patient care and impact public health. Because of these challenges, the Joint United Nations Programme on HIV/AIDS (UNAIDS), in partnership with other organizations, recently launched the Diagnostics Access Initiative. Expanding HIV programs, including the "test and treat" strategies and the newly established UNAIDS 90-90-90 targets, will require increased access to reliable and accurate POCT results. In this review, we examine various components that could improve access and uptake of quality-assured POC tests to ensure coverage and public health impact. These components include evaluation, policy, regulation, and innovative approaches to strengthen the quality of POCT.

Data connectivity: A critical tool for external quality assessment.

Point-of-care (POC) tests have been useful in increasing access to testing and treatment monitoring for HIV. Decentralising testing from laboratories to hundreds of sites around a country presents tremendous challenges in training and quality assurance. In order to address these concerns, companies are now either embedding connectivity in their new POC diagnostic instruments or providing some form of channel for electronic result exchange. These will allow automated key performance and operational metrics from devices in the field to a central database. Setting up connectivity between these POC devices and a central database at the Ministries of Health will allow automated data transmission, creating an opportunity for real-time information on diagnostic instrument performance as well as the competency of the operator through external quality assessment. A pilot programme in Zimbabwe shows that connectivity has significantly improve the turn-around time of external quality assessment result submissions and allow corrective actions to be provided in a timely manner. Furthermore, by linking the data to existing supply chain management software, stock-outs can be minimised. As countries are looking forward to achieving the 90-90-90 targets for HIV, such innovative technologies can automate disease surveillance, improve the quality of testing and strengthen the efficiency of health systems.

External quality assurance for HIV point-of-care testing in Africa: A collaborative country-partner approach to strengthen diagnostic services.

It is important to consider the role of diagnostics and the critical need for quality diagnostics services in resource-limited settings. Accurate diagnostic tests play a key role in patient management and the prevention and control of most infectious diseases. As countries plan for implementation of HIV early infant diagnosis and viral load point-of-care testing, the London School of Hygiene & Tropical Medicine has worked with countries and partners with an interest in external quality assurance to support quality point-of-care testing on the continent. Through a series of collaborative consultations and workshops, the London School of Hygiene & Tropical Medicine has gathered lessons learned, tools, and resources and developed quality assurance models that will support point-of-care testing. The London School of Hygiene & Tropical Medicine is committed to the continued advancement of laboratory diagnostics in Africa and quality laboratory services and point-of-care testing.

Quality assurance for HIV point-of-care testing and treatment monitoring assays.

In 2015, UNAIDS launched the 90-90-90 targets aimed at increasing the number of people infected with HIV to become aware of their status, access antiretroviral therapies and ultimately be virally suppressed. To achieve these goals, countries may need to scale up point-of-care (POC) testing in addition to strengthening central laboratory services. While decentralising testing increases patient access to diagnostics, it presents many challenges with regard to training and assuring the quality of tests and testing. To ensure synergies, the London School of Hygiene & Tropical Medicine held a series of consultations with countries with an interest in quality assurance and their implementing partners, and agreed on an external quality assessment (EQA) programme to ensure reliable results so that the results lead to the best possible care for HIV patients. As a result of the consultations, EQA International was established, bringing together EQA providers and implementers to develop a strategic plan for countries to establish national POC EQA programmes and to estimate the cost of setting up and maintaining the programme. With the dramatic increase in the number of proficiency testing panels required for thousands of POC testing sites across Africa, it is important to facilitate technology transfer from global EQA providers to a network of regional EQA centres in Africa for regional proficiency testing panel production. EQA International will continue to identify robust and cost-effective EQA technologies for quality POC testing, integrating novel technologies to support sustainable country-owned EQA programmes in Africa.

The WHO AFRO external quality assessment programme (EQAP): Linking laboratory networks through EQA programmes.

External Quality Assessment (EQA) surveys performed by the World Health Organization Regional Office for Africa (WHO AFRO) revealed the need for the strengthening of public health microbiology laboratories, particularly for testing of epidemic-prone diseases in the African Region. These surveys revealed common issues such as supply chain management, skilled personnel, logistical support and overall lack of quality standards. For sustainable improvements to health systems as well as global health security, deficiencies identified need to be actively corrected through robust quality assurance programmes and implementation of laboratory quality management systems. Given all the pathogens of public health importance, an external quality assessment programme with a focus on vaccine-preventable diseases and emerging and re-emerging dangerous pathogens is important, and should not be stand-alone, but integrated within laboratory networks as seen in polio, measles, yellow fever and rubella. In 2015, WHO AFRO collaborated with the US Centers for Disease Control and Prevention, the London School of Hygiene & Tropical Medicine and partners in a series of consultations with countries and national and regional EQA providers for the development of quality assurance models to support HIV point-of-care testing and monitoring. These consultations revealed similar challenges as seen in the WHO AFRO surveys. WHO AFRO brought forth its experience in implementing quality standards for health programmes, and also opened discussions on how lessons learned through such established programmes can be utilised to supporting and strengthening the introduction of early infant diagnosis of HIV and viral load point-of-care testing. An optimised external quality assessment programme will impact the ability of countries to meet core capacities, providing improved quality management systems, improving the confidence of diagnostic network services in Africa, and including capacities to detect events of international public health importance.

A gp41-based heteroduplex mobility assay provides rapid and accurate assessment of intrasubtype epidemiological linkage in HIV type 1 heterosexual transmission Pairs.

A critical step in HIV-1 transmission studies is the rapid and accurate identification of epidemiologically linked transmission pairs. To date, this has been accomplished by comparison of polymerase chain reaction (PCR)-amplified nucleotide sequences from potential transmission pairs, which can be cost-prohibitive for use in resource-limited settings. Here we describe a rapid, cost-effective approach to determine transmission linkage based on the heteroduplex mobility assay (HMA), and validate this approach by comparison to nucleotide sequencing. A total of 102 HIV-1-infected Zambian and Rwandan couples, with known linkage, were analyzed by gp41-HMA. A 400-base pair fragment within the envelope gp41 region of the HIV proviral genome was PCR amplified and HMA was applied to both partners' amplicons separately (autologous) and as a mixture (heterologous). If the diversity between gp41 sequences was low (<5%), a homoduplex was observed upon gel electrophoresis and the transmission was characterized as having occurred between partners (linked). If a new heteroduplex formed, within the heterologous migration, the transmission was determined to be unlinked. Initial blind validation of gp-41 HMA demonstrated 90% concordance between HMA and sequencing with 100% concordance in the case of linked transmissions. Following validation, 25 newly infected partners in Kigali and 12 in Lusaka were evaluated prospectively using both HMA and nucleotide sequences. Concordant results were obtained in all but one case (97.3%). The gp41-HMA technique is a reliable and feasible tool to detect linked transmissions in the field. All identified unlinked results should be confirmed by sequence analyses.

Role of donor genital tract HIV-1 diversity in the transmission bottleneck.

The predominant mode of HIV-1 infection is heterosexual transmission, where a genetic bottleneck is imposed on the virus quasispecies. To probe whether limited genetic diversity in the genital tract (GT) of the transmitting partner drives this bottleneck, viral envelope sequences from the blood and genital fluids of eight transmission pairs from Rwanda and Zambia were analyzed. The chronically infected transmitting partner's virus population was heterogeneous with distinct genital subpopulations, and the virus populations within the GT of two of four women sampled longitudinally exhibited evidence of stability over time intervals on the order of weeks to months. Surprisingly, the transmitted founder variant was not derived from the predominant GT subpopulations. Rather, in each case, the transmitting variant was phylogenetically distinct from the sampled locally replicating population. Although the exact distribution of the virus population present in the GT at the time of transmission cannot be unambiguously defined in these human studies, it is unlikely, based on these data, that the transmission bottleneck is driven in every case by limited viral diversity in the donor GT or that HIV transmission is solely a stochastic event.

Indeterminate and discrepant rapid HIV test results in couples' HIV testing and counselling centres in Africa.

BACKGROUND: Many HIV voluntary testing and counselling centres in Africa use rapid antibody tests, in parallel or in sequence, to establish same-day HIV status. The interpretation of indeterminate or discrepant results between different rapid tests on one sample poses a challenge. We investigated the use of an algorithm using three serial rapid HIV tests in cohabiting couples to resolve unclear serostatuses. METHODS: Heterosexual couples visited the Rwanda Zambia HIV Research Group testing centres in Kigali, Rwanda, and Lusaka, Zambia, to assess HIV infection status. Individuals with unclear HIV rapid antibody test results (indeterminate) or discrepant results were asked to return for repeat testing to resolve HIV status. If either partner of a couple tested positive or indeterminate with the screening test, both partners were tested with a confirmatory test. Individuals with indeterminate or discrepant results were further tested with a tie-breaker and monthly retesting. HIV-RNA viral load was determined when HIV status was not resolved by follow-up rapid testing. Individuals were classified based on two of three initial tests as "Positive", "Negative" or "Other". Follow-up testing and/or HIV-RNA viral load testing determined them as "Infected", "Uninfected" or "Unresolved". RESULTS: Of 45,820 individuals tested as couples, 2.3% (4.1% of couples) had at least one discrepant or indeterminate rapid result. A total of 65% of those individuals had follow-up testing and of those individuals initially classified as "Negative" by three initial rapid tests, less than 1% were resolved as "Infected". In contrast, of those individuals with at least one discrepant or indeterminate result who were initially classified as "Positive", only 46% were resolved as "Infected", while the remainder was resolved as "Uninfected" (46%) or "Unresolved" (8%). A positive HIV serostatus of one of the partners was a strong predictor of infection in the other partner as 48% of individuals who resolved as "Infected" had an HIV-infected spouse. CONCLUSIONS: In more than 45,000 individuals counselled and tested as couples, only 5% of individuals with indeterminate or discrepant rapid HIV test results were HIV infected. This represented only 0.1% of all individuals tested. Thus, algorithms using screening, confirmatory and tie-breaker rapid tests are reliable with two of three tests negative, but not when two of three tests are positive. False positive antibody tests may persist. HIV-positive partner serostatus should prompt repeat testing.

Alzheimer's presenilin 1 causes chromosome missegregation and aneuploidy.

Mutations in the presenilin 1 gene cause most early onset familial Alzheimer's disease (FAD). Here, we report that a defect in the cell cycle - improper chromosome segregation - can be caused by abnormal presenilin function and therefore may contribute to AD pathogenesis. Specifically we find that either over-expression or FAD mutation in presenilin 1 (M146L and M146V) leads to chromosome missegregation and aneuploidy in vivo and in vitro: (1) Up to 20% of lymphocytes and neurons of FAD-PS-1 transgenic and knocking mice are aneuploid by metaphase chromosome analysis and in situ hybridization. (2) Transiently transfected human cells over-expressing normal or mutant PS-1 develop similar aneuploidy within 48 h, including trisomy 21. (3) Mitotic spindles in the PS-1 transfected cells contain abnormal microtubule arrays and lagging chromosomes. Several mechanisms by which chromosome missegregation induced by presenilin may contribute to Alzheimer's disease are discussed.