Tracing Strategies Research Articles

Current Experience and Future Challenges of COVID-19 in Sri Lanka: An Auto-Ethnographic Study

Purpose: Sri Lanka a Lower Middle Income Country (LMIC) has focussed mainly on public health measures to contain COVID-19 pandemic. The objective of this paper is to describe the efforts undertaken in Sri Lanka to manage COVID-19 pandemic and to learn from shared experiences. Methods: This study was conducted as an auto-ethnographic study. Narrative accounts of key team members of Sri Lanka’s pandemic management teams were synthesized into a master narrative. Results: Authors’ experiences are described below under the following themes: Surveillance and public health actions, test, isolate and trace strategy, infection prevention and control strategy, communication strategies and challenges. Sri Lanka adopted a screen and quarantine policy for all arrivals after the first patient and identified high risk areas. Polymerase-ChainReaction (PCR) testing capacity was achieved rapidly. All potential patients were tested and isolated if positive regardless of symptoms. Aggressive contact tracing was undertaken, Hospitals and other institutions were remodified to accommodate and isolate all COVID-19 positive cases. Quarantine centers were created when home quarantine was unsatisfactory and mobility restrictions were placed and expanded as lockdowns or curfews. Communication channels were developed for healthcare workers, other public sectors and the community. Extensive collaboration and community support helped to mitigate some of the challenges. Conclusion: Sri Lanka was able to confine COVID-19 to population clusters using the ‘test, isolate and trace’ policy. There is concern regarding the long term feasibility of this policy, the economic impact of lockdowns and the threat for rapid spread on relaxing current public health measures.

On the effect of the number of tests and their time of application in tracing policies against COVID-19.

In this paper we explore the effect of the number of daily tests on an epidemics control policy purely based on testing and selective quarantine, and the impact of these actions depending on the time their application starts. We introduce a general model incorporating a stochastic disease evolution, a particular weighted graph representing the population, and an optimal contact tracing strategy to allocate available tests. Simulations on a community of 50’000 individuals show that the evolution of the epidemic produces a clear non-linear response to the variation of the number of tests used and to the starting time of their application. These results suggest that not only a minimum number of tests is necessary to obtain a positive outcome from the tracing strategy but also that there exists a saturation on the contribution of additional tests. The results also show that the timing in the application of the measures is as important as the measures themselves and that an excessive delay can be hardly overcome.

An ultrasensitive chemiluminescent biosensor for tracing glutathione in human serum using BSA@AuNCs as a peroxidase-mimetic nanozyme on a luminol/artesunate system.

In this work, a nanosensor chemiluminescent (CL) probe for sensing glutathione (GSH) was developed, for the first time, based on its inhibition of the intrinsic peroxidase-mimetic effect of BSA@AuNCs. The endoperoxide linkage of artesunate could be hydrolyzed by BSA@AuNCs resulting in the release of reactive oxygen species (ROS), and the consequent generation of strong CL emission. By virtue of the strong covalent interactions of -S⋯Au-, GSH could greatly suppress the peroxidase-mimetic effect of BSA@AuNCs, leading to a drastic CL quenching. The CL quenching efficiency increased proportionally to the logarithm of GSH concentration through the linearity range of 50.0-5000.0 nM with a limit of detection of 5.2 nM. This CL-based strategy for GSH tracing demonstrated the advantages of ultrasensitivity, high selectivity and simplicity. This strategy was successfully utilized to measure GSH levels in human serum with reasonable recovery results of 98.71%, 103.18%, and 101.68%, suggesting that this turn-off CL sensor is a promising candidate for GSH in biological and clinical samples.

Severe acute respiratory syndrome coronavirus 2 immunoglobulin G antibody: Seroprevalence among contacts of COVID-19 cases.

Multiple serosurveillance studies have focused on the presence of antibodies against severe acute respiratory syndrome coronavirus 2 in the general population and confirmed cases. However, seroprevalence of immunoglobulin G (IgG) among contacts of confirmed cases can add further value to the scientific findings. The objective is to estimate COVID-19 seropositivity among contacts of COVID-19 cases and to compare the seropositivity between types of contact for the assessment of differential risk and transmission dynamics. Large scale population-based serosurveillance on contacts of COVID-19 cases was carried out during the second half of August 2020 in Ahmedabad using the COVID-Kavach. The seropositivity among contacts was estimated and correlated-compared with type of contact and other demographic factors. With 1268 positive for IgG antibodies from 3973 samples, the seropositivity against COVID-19 among contacts of cases in Ahmedabad was 31.92% (95% confidence interval 30.48%-33.38%). The seropositivity among family contacts was significantly higher (39.36%) as compared to other contacts (28.72%) (Z = 6.60, P < 0.01). This trend is seen across all age groups and both the sex groups. The seropositivity has increasing trend with increasing age and is significantly higher among females (35.11%) than males (28.95%) (Z = 4.16, P < 0.01). Seropositivity of 31.92% among contacts indicates that a large proportion of contacts have already acquired immunity on account of their contact with the case. Higher seropositivity among family contacts justifies the risk categorization and testing strategy adopted for the contacts of the cases. This also reaffirms the need for contact tracing strategy for controlling the inevitable spread of pandemic.

Interim Evaluation of South Korea’s Response to COVID-19 and Preparation for a Post-COVID-19 World in Public Health

The aims of this study are to describe the key success factors of South Korea’s response to COVID-19 and to prepare for the post-COVID-19 world in public health. The MERS-CoV outbreak in 2015 provided the country with opportunities to enhance its national public health capacity in responding to emerging diseases, particularly in the areas of governance, testing, and tracing strategies, public-private partnership, risk communication, and the legal system supporting the government’s actions. This newly established system played a key role in South Korea’s relatively successful response to COVID-19. In this study, I evaluate that response and propose public health policies with a view to preparing for the post- COVID-19 world.

69. Effective Contact Tracing Strategies for COVID-19: A Municipal Health Department’s Model

BackgroundDuring the COVID-19 pandemic, contact tracing program as part of a larger epidemiological case investigation was effectively implemented by the local department of health in Paterson, NJ. The Paterson Communicable Disease Strike Team (PCDST) was established by leveraging skills and using existing public health staff of the health department team which led to a timely and robust public health intervention.MethodsPCDST comprised of 25 communicable disease investigators/contact tracers established in preparation for public health response in the event of large-scale communicable disease outbreaks pre-COVID. In March 2020 with initial COVID-19 cases in Paterson, PCDST was activated utilizing NJ DOH’s Communicable Disease Reporting and Surveillance System (CDRSS). Additional staff members were cross-trained to augment team as new cases surged. A triage coordinator would identify and assign new cases to disease investigators at a 24/7 schedule. Disease Investigators would provide test results, perform epidemiological case interviews, elicit close contacts, and provide isolation/quarantine recommendations. Case-contact monitors followed up daily basis until completion of isolation/quarantine period.ResultsAs of June 15, 2020, 6537 cases tested COVID-19 (+) in Paterson, NJ. 91% of cases and their contacts were interviewed. Peak occurred in mid-April with 263 cases on a single day. By mid-June, daily number of cases declined to 7/day. Reported COVID-19 mortality rate in Paterson (4.65%), compared to surrounding towns in the same county of Passaic (6%), other large cities in New Jersey (Newark 8%, Jersey City 7.4%) and New Jersey state (7.59%).ConclusionDespite limited resources, we were able to cross train and engage our frontline public health team (PCDST) to investigate and effectively contact trace new COVID-19 cases to help contain spread of infection. Although its unclear if our intervention impacted mortality rates, it is certain that contact tracing using a trained public health workforce is a model that has proven successful in Paterson. A local public health workforce vested in their communities can develop rapport needed to build trust and confidence in an intervention that elicits confidential medical information to limit viral transmission.Disclosures All Authors: No reported disclosures

368. Clinical Characteristics of Hospitalized COVID-19 American Indian Patients in Rural Arizona

BackgroundAmerican Indians have an increased risk of serious complications from COVID-19 due to the high prevalence of comorbidities such as diabetes, heart disease, obesity, and asthma. To date, there has been limited analysis of COVID-19 in the AI population. This study describes the characteristics of hospitalized COVID-19 patients from a well-defined AI population in eastern Arizona. Additionally, we explored the impact of early referral via contact tracing versus those who self-presented.MethodsRetrospective chart reviews were completed for patients hospitalized for COVID from March 29 to May 16, 2020. Summary statistics were used to describe demographics, symptoms, pre-existing conditions, and hospitalization data.ResultsWe observed 447 laboratory-confirmed cases of COVID-19, resulting in 71 (15.9%) hospitalizations over a 7-week period and a hospitalization rate of 159 per 1,000 persons. Of the 50 hospitalizations reviewed sequentially, 56% were female, median age of 55 (IQR 44–65). Median number of days hospitalized was 4 (2–6), with 16% requiring intensive care unit support, 15% intubated, 12% readmitted, and 10% deceased. 67% had an epidemiological link, and 32% had an emergency department or outpatient clinic visit within 7 days of hospitalization. All patients were symptomatic; the most common symptoms were cough (90%), shortness of breath (78%), and subjective fever (66%). 86% of patients had a pre-existing condition; the most common pre-existing conditions were diabetes (66%), obesity (58%), and hypertension (52%, Figure 1). All patients had elevated LDH, 94% had elevated CRP, 86% had elevated d-dimer, and 40% had lymphopenia; only 10% had an elevated WBC count and 26% had thrombocytopenia (Table 1). 26% of the patients were referred in by the tracing team (Table 2). Analysis of 500 hospitalizations will be available in October 2020. ConclusionMost AI patients hospitalized had a pre-existing condition, symptoms of cough or shortness of breath, and elevated LDH, CRP, and d-dimer. More research is needed to understand the patterns of COVID-19 related disease in vulnerable populations, like AI/AN, and to examine the utility of early referral by contact tracing teams in rural settings which may guide future tracing strategies.Disclosures All Authors: No reported disclosures

COVID-19 testing strategy in response to infection among healthcare workers in a large non-COVID-designated hospital

ABSTRACT Sarawak General Hospital, which is the only public access tertiary referral center in Sarawak State for all clinical specialties, was designated a hybrid hospital to treat both COVID-19 and non-COVID-19 patients. During the initial surge of patients admitted with COVID-19, there was also a corresponding increase in health-care workers (HCWs) detected with COVID-19 infection. The latter being isolated, and the large number of staff members that had come into contact with COVID-19 being quarantined from work, placed further strain on the health-care services. The staff mass screening strategy was a policy decision made by the hospital in response to infection among HCWs, and it aimed to reduce in-hospital transmission (particularly among asymptomatic staff), mitigate workforce depletion due to quarantining, and protect the health-care workforce. In this study, we assessed the detection rate of COVID-19 infection from staff mass testing over a five-week period, and described our experience of adopting this surveillance screening strategy alongside ongoing contact tracing and symptomatic screening strategies. Although it was thought that such periodic staff surveillance might be helpful in protecting the health-care workforce within a short period, the long-term implications, especially in settings with limited resources, is significant and therefore explored in this paper. Our findings might provide an evidence-based reference for the future planning of an optimal strategy with the least compromise in care for a larger proportion of non-COVID-19 patients amid efforts against COVID-19 in a large non-COVID-designated hospital with hybrid status.

South Korea's Soft Power in the Era of the Covid-19 Pandemic-An Analysis of the Expert Survey in Europe

Since the recent outbreak of the Covid-19, South Korea has demonstrated successful pandemic management that can be exemplary to other countries. This paper analyzes how South Korea's responses to the Covid-19 pandemic has changed the perceptions of the country in Europe. Through a survey conducted with Korea experts in 16 European countries, this paper documents the positive recognition of South Korea's pandemic management by the European public. Part of the positive appraisal can be attributed to South Korea's extensive testing, high technology, and the culture of wearing a face mask, while the opinions were more mixed regarding its comprehensive tracking and tracing strategy due to privacy concerns. Furthermore, the findings of the survey show that Europeans' overall perception of South Korea has improved together with its Covid-19 management. This evidence suggests that the country's success in pandemic management can be an instrument of public diplomacy to enhance its soft power, for which the government of South Korea currently invests considerable efforts.

Social distancing as a strategy to prevent respiratory virus infections.

Social distancing as a strategy to prevent respiratory virus infections.

A blueprint for effective pandemic mitigation

Traditional methods for mitigating pandemics employ a dual strategy of contact tracing plus testing combined with quarantining and isolation. The contact tracing aspect is usually done via manual (human) contact tracers, which are labor-intensive and expensive. In many large-scale pandemics (e.g., COVID-19), testing capacity is resource limited, and current myopic testing strategies are resource wasteful. To address these challenges, in this work, we provide a blueprint on how to contain the spread of a pandemic by leveraging wireless technologies and advances in sequential learning for efficiently using testing resources in order to mitigate the spread of a large-scale pandemic.&#x0D; We study how different wireless technologies could be leveraged to improve contact tracing and reduce the probabilities of detection and false alarms. The idea is to integrate different streams of data in order to create a susceptibility graph whose nodes correspond to an individual and whose links correspond to spreading probabilities. We then show how to develop efficient sequential learning based algorithms in order to minimize the spread of the virus infection. In particular, we show that current contact tracing plus testing strategies that are aimed at identifying (and testing) individuals with the highest probability of infection are inefficient. Rather, we argue that in a resource constrained testing environment, it is instead better to test those individuals whose expected impact on virus spread is the highest. We rigorously formulate the resource constrained testing problem as a sequential learning problem and provide efficient algorithms to solve it. We also provide numerical results that show the efficacy of our testing strategy.

To quarantine, or not to quarantine: A theoretical framework for disease control via contact tracing

Contact tracing via smartphone applications is expected to be of major importance for maintaining control of the COVID-19 pandemic. However, viable deployment demands a minimal quarantine burden on the general public. That is, consideration must be given to unnecessary quarantining imposed by a contact tracing policy. Previous studies have modeled the role of contact tracing, but have not addressed how to balance these two competing needs. We propose a modeling framework that captures contact heterogeneity. This allows contact prioritization: contacts are only notified if they were acutely exposed to individuals who eventually tested positive. The framework thus allows us to address the delicate balance of preventing disease spread while minimizing the social and economic burdens of quarantine. This optimal contact tracing strategy is studied as a function of limitations in testing resources, partial technology adoption, and other intervention methods such as social distancing and lockdown measures. The framework is globally applicable, as the distribution describing contact heterogeneity is directly adaptable to any digital tracing implementation.

Modelling the health and economic impacts of different testing and tracing strategies for COVID-19 in the UK

Background: Coronavirus disease 2019 (COVID-19) is resurgent in the UK and health and economic costs of the epidemic continue to rise. There is a need to understand the health and economic costs of different courses of action. Methods: We combine modelling, economic analysis and a user-friendly interface to contrast the impact and costs of different testing strategies: two levels of testing within the current test-trace-isolate (TTI) strategy (testing symptomatic people, tracing and isolating everyone) and a strategy where TTI is combined with universal testing (UT; i.e. additional population testing to identify asymptomatic cases). We also model effective coverage of face masks. Results: Increased testing is necessary to suppress the virus after lockdown. Partial reopening accompanied by scaled-up TTI (at 50% test and trace levels), full isolation and moderately effective coverage of masks (30% reduction in overall transmission) can reduce the current resurgence of the virus and protect the economy in the UK. Additional UT from December 2020 reduces the epidemic dramatically by Jan 2021 when combined with enhanced TTI (70% test-trace levels) and full isolation. UT could then be stopped; continued TTI would prevent rapid recurrence. This TTI+UT combination can suppress the virus further to save ~20,000 more lives and avoid ~£90bn economic losses, though costs ~£8bn more to deliver. We assume that all traced and lab-confirmed cases are isolated. The flexible interface we have developed allows exploration of additional scenarios, including different levels of reopening of society after the second lockdown in England as well as different levels of effective mask coverage. Conclusions: Our findings suggest that increased TTI is necessary to suppress the virus and protect the economy after the second lockdown in England. Additional UT from December 2020 reduces the epidemic dramatically by Jan 2021 and could then be stopped, as continued TTI would prevent rapid recurrence.

Challenges facing COVID-19 in rural areas: An experience from Lebanon

The COVID-19 pandemic first affected Lebanon on February 21st, 2020, and one month later it reached Bcharri, a small remote town in northern Lebanon. When similar rural areas with under-equipped facilities and financial limitations are affected, outcomes could be catastrophic, raising the need for meticulous preparation and rapid response.In our study, we describe the different measures taken to prepare this town for the COVID-19 outbreak, as well as our rapid response after the first case was confirmed. We emphasize the distinctions and the needs of rural areas when facing such threats, and the importance of a proactive community and local initiatives. We also detail our contact tracing strategy and massive testing campaign, as well as our early management of patients infected with COVID-19. We hope that our experience can be reproducible in areas with similar rural settings, during the COVID-19 pandemic and future outbreaks.

Annals for Educators - 1 December 2020.

Annals for Educators - 1 December 2020.

Modelling the test, trace and quarantine strategy to control the COVID-19 epidemic in the state of São Paulo, Brazil.

Testing for detecting the infection by SARS-CoV-2 is the bridge between the lockdown and the opening of society. In this paper we modelled and simulated a test-trace-and-quarantine strategy to control the COVID-19 outbreak in the State of São Paulo, Brasil. The State of São Paulo failed to adopt an effective social distancing strategy, reaching at most 59% in late March and started to relax the measures in late June, dropping to 41% in 08 August. Therefore, São Paulo relies heavily on a massive testing strategy in the attempt to control the epidemic.Two alternative strategies combined with economic evaluations were simulated. One strategy included indiscriminately testing the entire population of the State, reaching more than 40 million people at a maximum cost of 2.25 billion USD, that would reduce the total number of cases by the end of 2020 by 90%. The second strategy investigated testing only symptomatic cases and their immediate contacts – this strategy reached a maximum cost of 150 million USD but also reduced the number of cases by 90%.The conclusion is that if the State of São Paulo had decided to adopt the simulated strategy on April the 1st, it would have been possible to reduce the total number of cases by 90% at a cost of 2.25 billion US dollars for the indiscriminate strategy but at a much smaller cost of 125 million US dollars for the selective testing of symptomatic cases and their contacts.

Molecular epidemiology in the HIV and SARS-CoV-2 pandemics.

Purpose of reviewThe aim of this review was to compare and contrast the application of molecular epidemiology approaches for the improved management and understanding of the HIV versus SARS-CoV-2 epidemics.Recent findingsMolecular biology approaches, including PCR and whole genome sequencing (WGS), have become powerful tools for epidemiological investigation. PCR approaches form the basis for many high-sensitivity diagnostic tests and can supplement traditional contact tracing and surveillance strategies to define risk networks and transmission patterns. WGS approaches can further define the causative agents of disease, trace the origins of the pathogen, and clarify routes of transmission. When coupled with clinical datasets, such as electronic medical record data, these approaches can investigate co-correlates of disease and pathogenesis. In the ongoing HIV epidemic, these approaches have been effectively deployed to identify treatment gaps, transmission clusters and risk factors, though significant barriers to rapid or real-time implementation remain critical to overcome. Likewise, these approaches have been successful in addressing some questions of SARS-CoV-2 transmission and pathogenesis, but the nature and rapid spread of the virus have posed additional challenges.SummaryOverall, molecular epidemiology approaches offer unique advantages and challenges that complement traditional epidemiological tools for the improved understanding and management of epidemics.

Implementation of a Pooled Surveillance Testing Program for Asymptomatic SARS-CoV-2 Infections on a College Campus - Duke University, Durham, North Carolina, August 2-October 11, 2020.

On university campuses and in similar congregate environments, surveillance testing of asymptomatic persons is a critical strategy (1,2) for preventing transmission of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19). All students at Duke University, a private research university in Durham, North Carolina, signed the Duke Compact (3), agreeing to observe mandatory masking, social distancing, and participation in entry and surveillance testing. The university implemented a five-to-one pooled testing program for SARS-CoV-2 using a quantitative, in-house, laboratory-developed, real-time reverse transcription-polymerase chain reaction (RT-PCR) test (4,5). Pooling of specimens to enable large-scale testing while minimizing use of reagents was pioneered during the human immunodeficiency virus pandemic (6). A similar methodology was adapted for Duke University's asymptomatic testing program. The baseline SARS-CoV-2 testing plan was to distribute tests geospatially and temporally across on- and off-campus student populations. By September 20, 2020, asymptomatic testing was scaled up to testing targets, which include testing for residential undergraduates twice weekly, off-campus undergraduates one to two times per week, and graduate students approximately once weekly. In addition, in response to newly identified positive test results, testing was focused in locations or within cohorts where data suggested an increased risk for transmission. Scale-up over 4 weeks entailed redeploying staff members to prepare 15 campus testing sites for specimen collection, developing information management tools, and repurposing laboratory automation to establish an asymptomatic surveillance system. During August 2-October 11, 68,913 specimens from 10,265 graduate and undergraduate students were tested. Eighty-four specimens were positive for SARS-CoV-2, and 51% were among persons with no symptoms. Testing as a result of contact tracing identified 27.4% of infections. A combination of risk-reduction strategies and frequent surveillance testing likely contributed to a prolonged period of low transmission on campus. These findings highlight the importance of combined testing and contact tracing strategies beyond symptomatic testing, in association with other preventive measures. Pooled testing balances resource availability with supply-chain disruptions, high throughput with high sensitivity, and rapid turnaround with an acceptable workload.

New approach for tuberculosis contact tracing implemented in the two regions of Kyrgyz Republic during 2017-2018.

Tuberculosis (TB) contact investigation as a proved approach for finding new TB cases, is not fully performed in Kyrgyzstan. In 2018, the country started aligning the National Guidelines for tracking contacts with the WHO recommendations by expanding the definition for TB index cases to all close contacts, regardless of their TB risk status. This cross-sectional census aimed to determine the active case detection changes among TB contacts after implementation of a new TB tracing strategy using the National Surveillance data. We compared populations in Chui and Issyk-Kul regions of Kyrgyzstan who had contacts with TB index cases before (2017) and after (2018) strategic changes for the rates of indexes, contacts, screened contacts, and detected TB among screened contacts. New TB tracing strategy resulted in increased numbers of indexes (21%) and contacts (36%). Though the smaller number of contacts (1730 vs. 1590) have been screened in 2018, the proportion of TB diagnosed was substantially higher (95% CI: 0.024-0.005; p = 0.002) in 2018 vs. 2017. The mean numbers of TB contacts per-one-index-case also has increased dramatically by 117% (1.8 vs. 3.9) in Chui and by 43% (3.0 vs. 4.3) in Issyk-Kul regions (95% CI: 3.20-3.37; p < 0.001 and 95% CI: 2.97-3.09; p < 0.001, respectively) between 2018 and 2017. Extending new tracing approach to other regions of Kyrgyzstan will increase the number of identified contacts, leading to better TB control in the country and prevention of more severe TB development among the unidentified contacts.

Abstract PO-104: Phenotypic mapping of pathological crosstalk between glioblastoma and innate immune cells by synthetic genetic tracing

Abstract Glioblastoma is a lethal brain tumor with a high degree of heterogeneity and resistance to therapy. The lack of genetic tracing approaches to selectively identify tumor states and fate transitions limited our understanding of tumor homeostasis. By translating glioblastoma subtype signatures into synthetic genetic tracing cassettes, we investigated tumor heterogeneity at cellular and molecular level, in vitro and in vivo. Synthetic genetic tracing demonstrated that proneural glioblastoma is a hardwired identity, whereas the mesenchymal glioblastoma is an adaptive and metastable state downstream pro-inflammatory and differentiation cues, similarly wired in breast and lung tumors. Importantly, we discovered that innate immune cells divert glioblastoma cells into a proneural-to-mesenchymal transition causal to therapeutic resistance. Systematic phenotypic mapping using synthetic locus control regions (sLCRs) is a simple, automated, and scalable strategy for genetic tracing, generally applicable to study developmental and disease homeostasis. In glioblastoma, it uncovered causality between various (micro)environmental, genetic and pharmacological perturbations and mesenchymal commitment. Citation Format: Matthias Jürgen Schmitt, Carlos Company, Yuliia Dramaretska, Iros Barozzi, Andreas Göhrig, Sonia Kertalli, Melanie Großmann, Heike Naumann, Jikke Wierikx, Danielle Hulsman, Rainer Glass, Massimo Squatrito, Michela Serresi, Gaetano Gargiulo. Phenotypic mapping of pathological crosstalk between glioblastoma and innate immune cells by synthetic genetic tracing [abstract]. In: Proceedings of the AACR Virtual Special Conference on Tumor Heterogeneity: From Single Cells to Clinical Impact; 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr PO-104.