Evaluation of Diagnostic Tests for HIV Detection in Children in Malawi

Annually >40,000 Malawian babies are exposed to HIV, and >1800 get infected. Maternal antibodies limit the utility of HIV antibody testing in children <18 months, and HIV-DNA-PCR is preferred. However, HIV-PCR testing sites are few, PCR is expensive and PCR result turn-around-times (TAT) average 3 months leading to ~ 1/3rd of tested infants being lost to follow-up. A point-of-care HIV Test (POCT) may improve testing uptake and infant retention. This study aimed to identify an appropriate POCT for HIV diagnosis in children <18 months of age and to estimate its impact on infant diagnosis and linkage to HIV care. We conducted mixed methods study in two hospitals in Southern Malawi and evaluated: (1) performance, TAT, usability, acceptability, cost and cost-effectiveness for XpertHIV and compared it with HIV-DNA-PCR, and (2) performance and accuracy of plasma IP-10 in screening for HIV diagnosis and treatment failure among children aged 0-14 years; and (3) explored the potential role of HIV-LAMP assay in the diagnosis of HIV. XpertHIV had high sensitivity (97.8%) and specificity (98.1%). TAT was reduced from 24 days to 5.3 hours: 85% of the children-initiated ART on the day of testing. Compared with qPCR cost ($66.66), XpertHIV was cheaper at$42.34 per diagnostic test. With the difference in test costs, if XpertHIV is adopted nationwide for testing of 40,000 HIV exposed babies, Malawi could save ~USD2,193,538.88 annually. XpertHIV was acceptable to care givers, parents, laboratory technologists and nurses. Although IP-10 levels were higher in those with high viral load and under two years of age, it could not distinguish HIV from other infections. The HIV LAMP optimisation was unsuccessful. XpertHIV, if deployed in Malawi, could improve the diagnosis of paediatric HIV and its treatment uptake, and reduce costs of early infant diagnosis (EID). IP-10 is not an accurate screening marker for HIV in children. Further studies are needed to evaluate whether HIV LAMP is a suitable test for EI

A fast extraction-free isothermal LAMP assay for detection of SARS-CoV-2 with potential use in resource-limited settings

BACKGROUND: To retain the spread of SARS-CoV-2, fast, sensitive and cost-effective testing is essential, particularly in resource limited settings (RLS). Current standard nucleic acid-based RT-PCR assays, although highly sensitive and specific, require transportation of samples to specialised laboratories, trained staff and expensive reagents. The latter are often not readily available in low- and middle-income countries and this may significantly impact on the successful disease management in these settings. Various studies have suggested a SARS-CoV-2 loop mediated isothermal amplification (LAMP) assay as an alternative method to RT-PCR. METHODS: Four previously published primer pairs were used for detection of SARS-CoV-2 in the LAMP assay. To determine optimal conditions, different temperatures, sample input and incubation times were tested. Ninety-three extracted RNA samples from St. George's Hospital, London, 10 non-extracted nasopharyngeal swab samples from Great Ormond Street Hospital for Children, London, and 92 non-extracted samples from Queen Elisabeth Central Hospital (QECH), Malawi, which have previously been tested for SARS-Cov-2 by quantitative reverse-transcription RealTime PCR (qRT-PCR), were analysed in the LAMP assay. RESULTS: In this study we report the optimisation of an extraction-free colourimetric SARS-CoV-2 LAMP assay and demonstrated that a lower limit of detection (LOD) between 10 and 100 copies/µL of SARS-CoV-2 could be readily detected by a colour change of the reaction within as little as 30 min. We further show that this assay could be quickly established in Malawi, as no expensive equipment is necessary. We tested 92 clinical samples from QECH and showed the sensitivity and specificity of the assay to be 86.7% and 98.4%, respectively. Some viral transport media, used routinely to stabilise RNA in clinical samples during transportation, caused a non-specific colour-change in the LAMP reaction and therefore we suggest collecting samples in phosphate buffered saline (which did not affect the colour) as the assay allows immediate sample analysis on-site. CONCLUSION: SARS-CoV-2 LAMP is a cheap and reliable assay that can be readily employed in RLS to improve disease monitoring and management

Costing and cost-effectiveness of Cepheid Xpert HIV -1 Qual Assay using whole blood protocol versus PCR by Abbott Systems in Malawi

Background Timely diagnosis of HIV in infants and children is an urgent priority. In Malawi, 40,000 infants annually are HIV exposed. However, gold standard polymerase-chain-reaction (PCR) based testing requires centralised laboratories, causing turn-around times (TAT) of 2 to 3 months and significant loss to follow-up. If feasible and acceptable, minimising diagnostic delays through HIV Point-of-care-testing (POCT) may be cost-effective. We assessed whether POCT Cepheid Xpert HIV-1 Qual assay whole blood (XpertHIV) was more cost-effective than PCR. Methods From July-August 2018, 700 PCR Abbott tests using dried blood spots (DBS) were performed on 680 participants who enrolled on the feasibility, acceptability and performance of the XpertHIV study. Newly identified HIV-positive DBS from the 680 participants were retested, so with confirmatory testing of the HIV-positive cases, 700 tests were performed. We conducted a cost-minimisation and cost-effectiveness analysis of XpertHIV against PCR, as the standard of care. A random sample of 200 caregivers from the 680 participants had semi-structured interviews to explore costs from a societal perspective of XpertHIV at Mulanje District Hospital, Malawi. Analysis used TAT as the primary outcome measure. Results were extrapolated from the study period (29 days) to a year (240 working days). Sensitivity analyses characterised individual and joint parameter uncertainty and estimated patient cost per test. Results During the study period, XpertHIV was cost-minimising at $42.34 per test compared to$66.66 for PCR. Over a year, XpertHIV remained cost-minimising at $16.12 compared to PCR at$27.06. From the patient perspective (travel, food, lost productivity), the cost per test of XpertHIV was $2.45. XpertHIV had a mean TAT of 7.10 hours compared to 153.15 hours for PCR. Extrapolates accounting for equipment costs, lab consumables and losses to follow up estimated annual savings of$2,193,538.88 if XpertHIV is used nationally, as opposed to PCR. Conclusions This preliminary evidence suggests that adopting POCT XpertHIV will save time, allowing HIV-exposed infants to receive prompt care and may improve outcomes. The Malawi government will pay less due to XpertHIV’s cost savings and associated benefits

'If I am on ART, my new-born baby should be put on treatment immediately': Exploring the acceptability, and appropriateness of Cepheid Xpert HIV-1 Qual assay for early infant diagnosis of HIV in Malawi.

Acknowledgements: The authors thank the participants and their caregivers for consenting to participate in this study. We also acknowledge the contribution of the staff of Mulanje District Hospital especially the laboratory staff and Deputy District Hospital Officer; HIV DETECT study team, paediatric nurses and health surveillance assistants for their support in recruitment of participants; the qualitative researchers/transcribers; and the Ministry of Health in particular Mr James Kandulu, the Acting Director of Diagnostics.Funder: Adalma FoundationEarly infant diagnosis of HIV (EID-HIV) is key to reducing paediatric HIV mortality. Traditional approaches for diagnosing HIV in exposed infants are usually unable to optimally contribute to EID. Point-of-care testing such as Cepheid Xpert HIV-1 Qual assay-1 (XPertHIV) are available and could improve EID-HIV in resource constrained and high HIV burden contexts. We investigated the acceptability and perceived appropriateness of XpertHIV for EID-HIV in Mulanje Hospital, Malawi. Qualitative cross-sectional study using semi-structured interviews (SSI) among caregivers and health care workers at Mulanje District Hospital. The qualitative study was nested within a larger diagnostic study that evaluated the performance of XpertHIV using whole-blood-sample in a resource limited and high burden setting. A total of 65 SSIs were conducted among caregivers (n = 60) and health care providers (n = 5). Data were coded using deductive and inductive approaches while thematic approach was used to analyse data. Point-of-care XPertHIV was perceived to be acceptable among caregivers and health care providers. Caregivers' motivations for accepting XPertHIV HIV-testing for their infants included perceived risk of HIV emanating from child's exposure and validation of caregiver's own HIV sero-status. Although concerns about pain of testing and blood sample volumes taken from an infant remained amplified, overall, both caregivers and health care providers felt XpertHIV was appropriate because of its quick result turn-around-time which decreased anxiety and stress, the prospect of early treatment initiation and reduction in hospital visits and related costs. Implementation of XpertHIV has a great potential to improve EID-HIV in Malawi because of its quick turn-around-time and associated benefits including overcoming access-related barriers. Scaled implementation of this diagnostic technology require a robust community engagement strategy for managing caregivers and community myths and misconceptions towards the amount of blood sample collected from infants