Heather M. Scobie

Bio: Heather M. Scobie is an academic researcher from Centers for Disease Control and Prevention. The author has contributed to research in topics: Vaccination & Tetanus. The author has an hindex of 11, co-authored 20 publications receiving 351 citations.

A digital microfluidic system for serological immunoassays in remote settings

Abstract: Serosurveys are useful for assessing population susceptibility to vaccine-preventable disease outbreaks. Although at-risk populations in remote areas could benefit from this type of information, they face several logistical barriers to implementation, such as lack of access to centralized laboratories, cold storage, and transport of samples. We describe a potential solution: a compact and portable, field-deployable, point-of-care system relying on digital microfluidics that can rapidly test a small volume of capillary blood for disease-specific antibodies. This system uses inexpensive, inkjet-printed digital microfluidic cartridges together with an integrated instrument to perform enzyme-linked immunosorbent assays (ELISAs). We performed a field validation of the system’s analytical performance at Kakuma refugee camp, a remote setting in northwestern Kenya, where we tested children aged 9 to 59 months and caregivers for measles and rubella immunoglobulin G (IgG). The IgG assays were determined to have sensitivities of 86% [95% confidence interval (CI), 79 to 91% (measles)] and 81% [95% CI, 73 to 88% (rubella)] and specificities of 80% [95% CI, 49 to 94% (measles)] and 91% [95% CI, 76 to 97% (rubella)] (measles, n = 140; rubella, n = 135) compared with reference tests (measles IgG and rubella IgG ELISAs from Siemens Enzygnost) conducted in a centralized laboratory. These results demonstrate a potential role for this point-of-care system in global serological surveillance, particularly in remote areas with limited access to centralized laboratories.

Integrated Serologic Surveillance of Population Immunity and Disease Transmission.

Abstract: Antibodies are unique among biomarkers in their ability to identify persons with protective immunity to vaccine-preventable diseases and to measure past exposure to diverse pathogens. Most infectious disease surveillance maintains a single-disease focus, but broader testing of existing serologic surveys with multiplex antibody assays would create new opportunities for integrated surveillance. In this perspective, we highlight multiple areas for potential synergy where integrated surveillance could add more value to public health efforts than the current trend of independent disease monitoring through vertical programs. We describe innovations in laboratory and data science that should accelerate integration and identify remaining challenges with respect to specimen collection, testing, and analysis. Throughout, we illustrate how information generated through integrated surveillance platforms can create new opportunities to more quickly and precisely identify global health program gaps that range from undervaccination to emerging pathogens to multilayered health disparities that span diverse communicable diseases.

Routine Vaccination Coverage in Northern Nigeria: Results from 40 District-Level Cluster Surveys, 2014-2015.

Abstract: Background Despite recent success towards controlling poliovirus transmission, Nigeria has struggled to achieve uniformly high routine vaccination coverage. A lack of reliable vaccination coverage data at the operational level makes it challenging to target program improvement. To reliably estimate vaccination coverage, we conducted district-level vaccine coverage surveys using a pre-existing infrastructure of polio technical staff in northern Nigeria. Methods Household-level cluster surveys were conducted in 40 polio high risk districts of Nigeria during 2014–2015. Global positioning system technology and intensive supervision by a pool of qualified technical staff were used to ensure high survey quality. Vaccination status of children aged 12–23 months was documented based on vaccination card or caretaker’s recall. District-level coverage estimates were calculated using survey methods. Results Data from 7,815 children across 40 districts were analyzed. District-level coverage with the third dose of diphtheria-pertussis-tetanus vaccine (DPT3) ranged widely from 1–63%, with all districts having DPT3 coverage below the target of 80%. Median coverage across all districts for each of eight vaccine doses (1 Bacille Calmette-Guerin dose, 3 DPT doses, 3 oral poliovirus vaccine doses, and 1 measles vaccine dose) was <50%. DPT3 coverage by survey was substantially lower (range: 28%–139%) than the 2013 administrative coverage reported among children aged <12 months. Common reported reasons for non-vaccination included lack of knowledge about vaccines and vaccination services (50%) and factors related to access to routine immunization services (15%). Conclusions Survey results highlighted vaccine coverage gaps that were systematically underestimated by administrative reporting across 40 polio high risk districts in northern Nigeria. Given the limitations of administrative coverage data, our approach to conducting quality district-level coverage surveys and providing data to assess and remediate issues contributing to poor vaccination coverage could serve as an example in countries with sub-optimal vaccination coverage, similar to Nigeria.

Impact of a Targeted Typhoid Vaccination Campaign Following Cyclone Tomas, Republic of Fiji, 2010

Abstract: After a category 4 cyclone that caused extensive population displacement and damage to water and sanitation infrastructure in Fiji in March 2010, a typhoid vaccination campaign was conducted as part of the post-disaster response. During June-December 2010, 64,015 doses of typhoid Vi polysaccharide vaccine were administered to persons ≥ 2 years of age, primarily in cyclone-affected areas that were typhoid endemic. Annual typhoid fever incidence decreased during the post-campaign year (2011) relative to preceding years (2008-2009) in three subdivisions where a large proportion of the population was vaccinated (incidence rate ratios and 95% confidence intervals: 0.23, 0.13-0.41; 0.24, 0.14-0.41; 0.58, 0.40-0.86), and increased or remained unchanged in 12 subdivisions where little to no vaccination occurred. Vaccination played a role in reducing typhoid fever incidence in high-incidence areas after a disaster and should be considered in endemic settings, along with comprehensive control measures, as recommended by the World Health Organization.

WHO and UNICEF Estimates of National Infant Immunization Coverage: Methods and processes/Estimations Par l'OMS et l'UNICEF Des Couvertures Vaccinales Des Nourrissons Par Pays : Methodes et procedures/Estimaciones De la OMS Y El UNICEF Sobre la Cobertura Nacional De Vacunacion De Los Lactantes: Metodos Y Procedimientos

Abstract: Introduction WHO recommends that all children receive one dose of bacille Calmette-Guerin vaccine (BCG), three doses of diphtheria--tetanus-pertussis vaccine (DTP), three doses of either oral polio vaccine (OPV) or inactivated polio vaccine (IPV), three doses of hepatitis B vaccine, and one dose of a measles virus-containing vaccine (MVCV), either anti-measles alone or in combination with other antigens (1-9) It also recommends three doses of vaccine against infection with Haemophilus influenzae type b (Hib) (10) To boost immunity at older ages, additional immunizations are recommended for healthcare workers, travellers, high-risk groups and people in areas where the risk of specific vaccine-preventable diseases is high (11) Immunization coverage levels and trends are used (i) to monitor the performance of immunization services locally, nationally and internationally; (ii) to guide strategies for the eradication, elimination and control of vaccine-preventable diseases; (12-14) (iii) to identify areas of immunization systems that may require additional resources and focused attention; (15,16) and (iv) to assess the need to introduce new vaccines into national and local immunization systems (17) Models of vaccine-preventable disease burden frequently include immunization coverage levels among their components (18-20) Coverage levels for measles vaccine and DTP are indicators of health system performance frequently considered by funding agencies when reviewing applications for financial and technical support (21-24) Measles immunization coverage is one of the indicators for tracking progress towards Millennium Development Goal 4, to reduce child mortality (25) Furthermore, trends in immunization coverage are used to establish the link between immunization service delivery and disease occurrence and to provide a framework for setting future coverage goals (26) Trends in immunization coverage While some countries had routine immunization systems in place before 1980, major national and international development of routine, universal infant immunization systems did not begin until the late 1970s In fact, it was not until the 1980s that dramatic improvements in immunization coverage were achieved, along with an increase in coverage with the third dose of DTP vaccine (DTP3) from 20% in 1980 to 75% coverage in 1990 While some countries reported significant declines in coverage after 1990, global coverage levels remained fairly constant and began rising slowly but steadily in 2000, until DTP3 coverage worldwide had reached 81% in 2006 In 1980, fewer than 10% of the world's children lived in 20 of the 167 countries with DTP3 coverage levels greater than 80%; 84% of the world's children lived in countries where coverage was less than 50% By 1990, 108 countries (43% of all children) had DTP3 coverage levels greater than 80%, and fewer than 10% of children lived in countries with under 50% coverage Although national coverage levels can "mask" sub-national geographical or sociological pockets where coverage is much lower, in 2006, 57% of children lived in countries with greater than 80% DTP3 coverage Still, that year approximately 263 million children who reached their first birthday did not receive DTP3, but 162 million (62%) of them lived in China, India, Indonesia or Nigeria At the time this report was prepared, there remained seven countries where fewer than half of the children were vaccinated with three doses of DTP3: Angola, Central African Republic, Chad, Equatorial Guinea, Gabon, Niger and Somalia" WHO and UNICEF publish annual estimates of national immunization coverage; (27-30) such estimates have been available by country since 1980 at http://wwwwhoint/immunization_monitoring/en/globalsummary/ wucoveragecountrylistcfm and http://wwwchildinfoorg/immunization_countryreportshtml Additional analyses can be found at http://wwwwhoint/immunization_monitoring/data/en/and http://www …

Difficult-to-Treat Resistance in Gram-negative Bacteremia at 173 US Hospitals: Retrospective Cohort Analysis of Prevalence, Predictors, and Outcome of Resistance to All First-line Agents.

Abstract: Background Resistance to all first-line antibiotics necessitates the use of less effective or more toxic “reserve” agents Gram-negative bloodstream infections (GNBSIs) harboring such difficult-to-treat resistance (DTR) may have higher mortality than phenotypes that allow for ≥1 active first-line antibiotic

Paper-based microfluidics for DNA diagnostics of malaria in low resource underserved rural communities

Abstract: Rapid, low-cost, species-specific diagnosis, based upon DNA testing, is becoming important in the treatment of patients with infectious diseases. Here, we demonstrate an innovation that uses origami to enable multiplexed, sensitive assays that rival polymerase chain reactions (PCR) laboratory assays and provide high-quality, fast precision diagnostics for malaria. The paper-based microfluidic technology proposed here combines vertical flow sample-processing steps, including paper folding for whole-blood sample preparation, with an isothermal amplification and a lateral flow detection, incorporating a simple visualization system. Studies were performed in village schools in Uganda with individual diagnoses being completed in <50 min (faster than the standard laboratory-based PCR). The tests, which enabled the diagnosis of malaria species in patients from a finger prick of whole blood, were both highly sensitive and specific, detecting malaria in 98% of infected individuals in a double-blind first-in-human study. Our method was more sensitive than other field-based, benchmark techniques, including optical microscopy and industry standard rapid immunodiagnostic tests, both performed by experienced local healthcare teams (which detected malaria in 86% and 83% of cases, respectively). All assays were independently validated using a real-time double-blinded reference PCR assay. We not only demonstrate that advanced, low-cost DNA-based sensors can be implemented in underserved communities at the point of need but also highlight the challenges associated with developing and implementing new diagnostic technologies in the field, without access to laboratories or infrastructure.