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Oxford Centre for Tropical Medicine and Global Health
When health data go dark: the importance of the DHS Program and imagining its future.
BACKGROUND: The suspension and/or termination of many programmes funded through the United States Agency for International Development (USAID) by the new US administration has severe short- and long-term negative impacts on the health of people worldwide. We draw attention to the termination of the Demographic and Health Surveys (DHS) Program, which includes nationally representative surveys of households, DHS, Malaria Indicator Surveys [MIS]) and health facilities (Service Provision Assessments [SPA]) in over 90 low- and middle-income countries. USAID co-funding and provision of technical support for these surveys has been shut down. MAIN BODY: The impact of these disruptions will reverberate across local, regional, national, and global levels and severely impact the ability to understand the levels and changes in population health outcomes and behaviours. We highlight three key impacts on (1) ongoing data collection and data processing activities; (2) future data collection and consequent lack of population-level health indicators; and (3) access to existing data and lack of support for its use. CONCLUSIONS: We call for immediate action on multiple fronts. In the short term, universal access to existing data and survey materials should be restored, and surveys which were planned or in progress should be completed. In the long term, this crisis should serve as a tipping point for transforming these vital surveys. We call on national governments, regional organisations, and international partners to develop sustainable alternatives that preserve the principles (standardised questionnaires, backward compatibility, open access data with rigorous documentation) which made the DHS Program an invaluable global health resource.
Influence of context on engagement with COVID-19 testing: a scoping review of barriers and facilitators to testing for healthcare workers, care homes and schools in the UK.
ObjectiveThe UK government's response to the COVID-19 pandemic included a 'test, trace and isolate' strategy. Testing services for healthcare workers, care homes and schools accounted for the greatest spend and volume of tests. We reviewed relevant literature to identify common and unique barriers and facilitators to engaging with each of these testing services.DesignScoping review.Search strategyPubMed, Scopus and the WHO COVID-19 Research Database were searched for evidence published between 1 January 2020 and 7 November 2022. This was supplemented by evidence identified via free-text searches on Google Scholar and provided by the UK Health Security Agency (UKHSA).Data extraction and synthesisData were extracted by a team of reviewers and synthesised thematically under the broad headings of perceptions, experiences, barriers and facilitators to engaging with the COVID-19 testing programme.ResultsThis study included 40 sources, including 17 from projects that informed UKHSA's decisions during the pandemic. Eight themes emerged and were used to categorise barriers and facilitators to engaging with the testing services for healthcare workers, care homes and schools: (1) perceived value, (2) trust in the tests and public bodies, (3) importance of infrastructure, (4) impact of media and social networks, (5) physical burden of the test, (6) perceived capability to undertake testing, (7) importance of relevant information and 8) consequences of testing.ConclusionsUniversal barriers and facilitators to engagement with the testing programme related to the core elements of each testing service, such as uncomfortable specimen collection and the influence of media and peers; these could be mitigated or leveraged to increase engagement across settings. However, the individuals involved, perceptions of value and available resources differed across services, leading to unique experiences between settings. Thus, consideration of context is crucial when designing and implementing a testing programme in response to a pandemic.
The latency time of SARS-CoV- 2 Delta variant in infection- and vaccine-naive individuals from Vietnam
Abstract Background The latency time (from infection to infectiousness) guides the choice of measures required to control an infectious disease. Estimates of the SARS-CoV- 2 latency time are sparse due to lack of appropriate and representative data. Infection time is rarely known exactly and exposure information may be subject to several biases. Information on the endpoint requires repeated testing. Moreover, estimation is challenging because both the starting point and endpoint are typically interval censored and data may be subject to length-biased sampling (truncation). Methods We collected detailed information on exposure from public health reports produced during an outbreak with the SARS-CoV- 2 Delta variant in Ho Chi Minh City, Vietnam, in May-July 2021. Using a custom digital form and application facilitated reliable choices on exposure window. This comprehensive data set on exposure and test results from 1951 individuals, collected in the absence of large-scale vaccination or earlier infection, is the first of its kind outside of China. We accounted for the doubly interval censored nature of the observations and went beyond the standard assumption of a constant infection risk over calendar time (exponential growth) and allowed for flexibility regarding the latency time (generalized gamma distribution). We addressed right truncation due to a cutoff in data collection and a finite quarantine length. Employing a Bayesian approach, using the program , made the analyses relatively straightforward. Results Assuming exponential growth, our estimate of SARS-CoV- 2 Delta variant’s mean latency time was 3.22 (95% Credible Interval 2.89 - 3.55) days; the median was 1.81 (95% CrI 1.44- 2.16) days; the 95 th percentile was 10.98 (95% CrI 9.91 - 12.41) days. These values were much larger if a uniform infection risk was assumed. Conclusions Using a Bayesian approach with the program, we were able to estimate the SARS-CoV- 2 latency time distribution of the Delta variant in infection-naive and vaccine-naive individuals. Estimates were sensitive to the assumptions made regarding the risk of infection within the exposure window. Compared to earlier studies, the median latency time was shorter, while the 95 th percentile was larger. Our results stress the importance of thoughtful data collection and analysis for evidence-based control of an infectious disease.
Understanding the primary healthcare context in rural South and Southeast Asia: a village profiling study
Abstract Background Understanding contextual factors is critical to the success of health service planning and implementation. However, few contextual data are available at the village level in rural South and Southeast Asia. This study addressed the gap by profiling representative villages across seven sites in Thailand (n=3), Cambodia, Laos, Myanmar and Bangladesh. Methods Key informant surveys supplemented by other information sources were used to collect data from 687 villages on four key indicators (literacy rate, and percentages of attended deliveries, fully immunised children and latrine coverage), as well as access to various services. Data were analysed descriptively. Results Sites varied considerably. Five were highly diverse ethno-culturally and linguistically, and all relied on primary health centres and village health/malaria workers as the main providers of primary healthcare. These were generally bypassed by severely ill patients for urban first-level referral hospitals and private sector facilities. While >75% of villages were near primary schools, educational attainment was generally low. Over 70% of villages at each site had mobile phone coverage and availability of electricity was high (≥65% at all sites bar Myanmar). Conclusion These results illustrate the similarities and differences of villages in this region that must be considered in public health research and policymaking.
Progression of lymphatic filariasis antigenaemia and microfilaraemia over 4.5 years in antigen-positive individuals, Samoa 2019-2023
Objectives: The first round of triple-drug mass drug administration (MDA) for lymphatic filariasis (LF) in Samoa was in 2018. This study aims to i) examine progression of LF antigen (Ag) and microfilaria (Mf) in Ag-positive individuals from 2019-2023; and ii) compare Ag/Mf prevalence in household members of Mf-positive vs Mf-negative participants. Methods: In 2023, we tested Ag-positive participants (indexes) from a 2019 survey in Samoa, and their household members. We tested for Ag (Alere/Abbott Filariasis Test Strip) and Mf. We examined changes in Ag/Mf status in index participants and compared Ag/Mf prevalence between household members of Mf-positive and Mf-negative indexes. Results: We recruited 91 indexes and 317 household members. In 2023, all 17 Mf-positive indexes remained Ag-positive and 11/15 with Mf results (73.3%) were Mf-positive. Of 74 Mf-negative indexes, 79.7% remained Ag-positive in 2023 and 31.1% became Mf-positive. Household members of Mf-positive indexes were more likely to be Ag-positive (odds ratios 3.3, 95% CI 1.0-10.3) compared to those of Mf-negative indexes. Conclusion: Our results raise concerns regarding long-term effectiveness of a single-dose of triple-drug MDA for sustained clearance of Mf in Samoa. Guidelines for follow-up and treatment of Ag/Mf-positive people and household members are urgently required.
The respiratory syncytial virus vaccine and monoclonal antibody landscape: the road to global access.
Respiratory syncytial virus (RSV) is the second most common pathogen causing infant mortality. Additionally, RSV is a major cause of morbidity and mortality in older adults (age ≥60 years) similar to influenza. A protein-based maternal vaccine and monoclonal antibody (mAb) are now market-approved to protect infants, while an mRNA and two protein-based vaccines are approved for older adults. First-year experience protecting infants with nirsevimab in high-income countries shows a major public health benefit. It is expected that the RSV vaccine landscape will continue to develop in the coming years to protect all people globally. The vaccine and mAb landscape remain active with 30 candidates in clinical development using four approaches: protein-based, live-attenuated and chimeric vector, mRNA, and mAbs. Candidates in late-phase trials aim to protect young infants using mAbs, older infants and toddlers with live-attenuated vaccines, and children and adults using protein-based and mRNA vaccines. This Review provides an overview of RSV vaccines highlighting different target populations, antigens, and trial results. As RSV vaccines have not yet reached low-income and middle-income countries, we outline urgent next steps to minimise the vaccine delay.
Factors modulating maternofetal transfer of IgG antibodies following SARS-CoV-2 gestational infection.
Early infant immunity to SARS-CoV-2 depends on maternofetal transfer of antibodies. We aimed to analyze the factors modulating the maternofetal transfer of anti-SARS-CoV-2 IgG antibodies following gestational infection during the pandemic in Brazil (April-August 2021). We conducted a retrospective and prospective cohort study involving 509 mother-child dyads tested simultaneously for IgG anti-nucleocapsid antibodies during universal neonatal screening. There were 341 seronegative dyads and 168 seropositive ones. Seropositive neonates were retested two to three months later. We examined the association of neonatal serological status and IgG concentrations with gestational mRNA vaccination, timing of maternal infection, neonatal conditions, and gender. Gestational SARS-CoV-2 infection predicted neonatal IgG seropositivity (OR=3.97; 95%CI=2.69-5.88). Maternal infection in the first, second, or third trimester was associated with progressively greater seropositivity in neonates (34.4%, 51.6%, and 58.2%, respectively; p=0.03). Among seropositive neonates, IgG concentration was higher when mothers reported they had COVID-19 during pregnancy (p=0.04) and tended to be lower in girls (p=0.06). More than half of the seropositive neonates remained seropositive two to three months later (54.1%), which was associated with both maternal and neonatal IgG concentration at birth (p<0.001). Higher neonatal IgG concentrations at birth were associated with the persistence of anti-N IgG antibodies for two to three months in more than half of the seropositive newborns. This study provides an additional understanding of the dynamics of maternofetal antibody transfer.
Using a Machine Learning Approach to Predict Snakebite Envenoming Outcomes Among Patients Attending the Snakebite Treatment and Research Hospital in Kaltungo, Northeastern Nigeria
The Snakebite Treatment and Research Hospital (SBTRH) is a leading centre for snakebite envenoming care and research in sub-Saharan Africa, treating over 2500 snakebite patients annually. Despite routine data collection, routine analyses are seldom conducted to identify trends or guide clinical practices. This study retrospectively analyzes 1022 snakebite cases at SBTRH from January to June 2024. Most patients were adults (62%) and were predominantly male (72%). Key factors such as age, sex, and time between bite and hospital presentation were associated with outcomes, including recovery, amputation, debridement, and death. Adult males who took more than four hours to arrive to hospital were identified as a high-risk group for poor outcomes. Using patient characteristics, an XGBoost model was developed and was compared to Random Forest and logistic regression models. In general, all models had high positive predictive value and low sensitivity, meaning that if they predicted a patient to experience amputation, debridement, or death, that patient almost always actually experienced amputation, debridement, or death; however, most models rarely made this prediction. The XGBoost model with all features was optimal, given that it had both a high positive predictive value and relatively high sensitivity. This may be of significance to resource-limited settings like SBTRH, where antivenoms can be scarce; however, more research is needed to build better predictive models. These findings underscore the need for targeted interventions for high-risk groups, and further research and integration of machine-learning-driven decision support tools in low-resource-limited clinical settings.
Social and behavioral risk reduction strategies for tuberculosis prevention in Canadian Inuit communities: a cost-effectiveness analysis
Abstract Background Tuberculosis (TB) is an important public health problem in Inuit communities across Canada, with an annual incidence rate in 2017 that was nearly 300 times higher than in Canadian-born non-Indigenous individuals. Social and behavioral factors that are prevalent in the North, such as commercial tobacco use, excessive alcohol use, food insecurity and overcrowded housing put individuals at higher risk for TB morbidity and mortality. We examined the potential impact of mitigation strategies for these risk factors, in reducing TB burden in this setting. Methods We created a transmission model to simulate the epidemiology of TB in Nunavut, Canada. We then used a decision analysis model to assess the potential impact of several evidence-based strategies targeting tobacco use, excessive alcohol use, food insecurity and overcrowded housing. We predicted TB incidence, TB-related deaths, quality adjusted life years (QALYs), and associated costs and cost-effectiveness over 20 years. All costs were expressed in 2018 Canadian dollars. Results Compared to a status quo scenario with no new interventions for these risk factors, the reduction strategy for tobacco use was most effective and cost-effective, reducing TB incidence by 5.5% (95% uncertainty range: 2.7–11%) over 20 years, with an estimated cost of $95,835 per TB case prevented and $49,671 per QALY gained. The addition of the food insecurity reduction strategy reduced incidence by a further 2% (0.5–3%) compared to the tobacco cessation strategy alone, but at significant cost. Conclusions Strategies that aim to reduce commercial tobacco use and improve food security will likely lead to modest reductions in TB morbidity and mortality. Although important for the communities, strategies that address excess alcohol use and overcrowding will likely have a more limited impact on TB-related outcomes at current scale, and are associated with much higher cost. Their benefits will be more substantial with scale up, which will also likely have important downstream impacts such as improved mental health, educational attainment and food security.