scholarly journals Contact tracing and isolation reduces covid-19 incidence in a structured agent-based model

2020 ◽  
Author(s):  
Marcus Low ◽  
Nathan Geffen
Keyword(s):  
Disease Progression ◽  
Critical Role ◽  
Substantial Reduction ◽  
Secondary Analysis ◽  
World Health ◽  
Contact Tracing ◽  
Relative Reduction ◽  
Agent Based ◽  
The Mean ◽  
The Impact

AbstractBackgroundThe World Health Organization has identified contact tracing and isolation (CTI) as a key strategy to slow transmission of SARS-CoV-2. Structured agent-based models (ABMs) provide a means to investigate the efficacy of such strategies in heterogeneous populations and to explore the impact of factors such as changes in test turnaround times (TaT).MethodsWe developed a structured ABM to simulate key SARS-CoV-2 transmission and Covid-19 disease progression dynamics in populations of 10, 000 agents. We ran 10, 000 simulations of each of three scenarios: (1) No CTI with a TaT of two days, (2) CTI with a TaT of two days, and (3) CTI with a TaT of eight days. We conducted a secondary analysis in which TaT values were varied from two to 11. The primary outcome for all analyses was mean total infections.ResultsCTI reduced the mean number of infections from 5, 577 to 4, 157 (a relative reduction of 25.5%) when TaT was held steady at two days. CTI with a TaT of eight days resulted in a mean of 5, 163 infections (a relative reduction of 7.4% compared to no CTI and a TaT of two days). In the secondary analysis, every additional day added to the TaT increased the total number of infections – with the greatest increase in infections between four and five days, and the smallest increase between ten and 11 days.ConclusionsIn a structured ABM that simulates key dynamics of Covid-19 transmission and disease progression, CTI results in a substantial reduction in the mean number of total infections. The benefit is greater with shorter TaT times, but remained substantial even with TaTs of eight days. The results suggest that CTI may play a critical role in reducing the size of outbreaks and that TaTs should be kept as short as possible in order to maximise this benefit.

scholarly journals Exploring the effectiveness of a COVID-19 contact tracing app using an agent-based model

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jonatan Almagor ◽  
Stefano Picascia
Keyword(s):  
High Rate ◽  
Contact Tracing ◽  
Agent Based Model ◽  
Agent Based ◽  
The Social ◽  
Behavioural Factors ◽  
The Impact ◽  
Different Levels ◽  
User Rate

AbstractA contact-tracing strategy has been deemed necessary to contain the spread of COVID-19 following the relaxation of lockdown measures. Using an agent-based model, we explore one of the technology-based strategies proposed, a contact-tracing smartphone app. The model simulates the spread of COVID-19 in a population of agents on an urban scale. Agents are heterogeneous in their characteristics and are linked in a multi-layered network representing the social structure—including households, friendships, employment and schools. We explore the interplay of various adoption rates of the contact-tracing app, different levels of testing capacity, and behavioural factors to assess the impact on the epidemic. Results suggest that a contact tracing app can contribute substantially to reducing infection rates in the population when accompanied by a sufficient testing capacity or when the testing policy prioritises symptomatic cases. As user rate increases, prevalence of infection decreases. With that, when symptomatic cases are not prioritised for testing, a high rate of app users can generate an extensive increase in the demand for testing, which, if not met with adequate supply, may render the app counterproductive. This points to the crucial role of an efficient testing policy and the necessity to upscale testing capacity.

scholarly journals Investigating the effectiveness of re-opening policies before vaccination during a pandemic: SD modelling research based on COVID-19 in Wuhan

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ying Qian ◽  
Wei Xie ◽  
Jidi Zhao ◽  
Ming Xue ◽  
Shiyong Liu ◽  
...  
Keyword(s):  
Model Simulation ◽  
Control Measures ◽  
World Health ◽  
Contact Tracing ◽  
Infection Prevention And Control ◽  
Real World Data ◽  
Medical Resources ◽  
Health Organization ◽  
The Impact ◽  
Different Levels

Abstract Background Lockdown policies were widely adopted during the coronavirus disease 2019 (COVID-19) pandemic to control the spread of the virus before vaccines became available. These policies had significant economic impacts and caused social disruptions. Early re-opening is preferable, but it introduces the risk of a resurgence of the epidemic. Although the World Health Organization has outlined criteria for re-opening, decisions on re-opening are mainly based on epidemiologic criteria. To date, the effectiveness of re-opening policies remains unclear. Methods A system dynamics COVID-19 model, SEIHR(Q), was constructed by integrating infection prevention and control measures implemented in Wuhan into the classic SEIR epidemiological model and was validated with real-world data. The input data were obtained from official websites and the published literature. Results The simulation results showed that track-and-trace measures had significant effects on the level of risk associated with re-opening. In the case of Wuhan, where comprehensive contact tracing was implemented, there would have been almost no risk associated with re-opening. With partial contact tracing, re-opening would have led to a minor second wave of the epidemic. However, if only limited contact tracing had been implemented, a more severe second outbreak of the epidemic would have occurred, overwhelming the available medical resources. If the ability to implement a track-trace-quarantine policy is fixed, the epidemiological criteria need to be further taken into account. The model simulation revealed different levels of risk associated with re-opening under different levels of track-and-trace ability and various epidemiological criteria. A matrix was developed to evaluate the effectiveness of the re-opening policies. Conclusions The SEIHR(Q) model designed in this study can quantify the impact of various re-opening policies on the spread of COVID-19. Integrating epidemiologic criteria, the contact tracing policy, and medical resources, the model simulation predicts whether the re-opening policy is likely to lead to a further outbreak of the epidemic and provides evidence-based support for decisions regarding safe re-opening during an ongoing epidemic. Keyords COVID-19; Risk of re-opening; Effectiveness of re-opening policies; IPC measures; SD modelling.

scholarly journals A Computational Framework for Exploring the Socio-Cognitive Features of Teams and their Influence on Design Outcomes

2019 ◽  
Vol 1 (1) ◽  
pp. 1-10
Author(s):  
Harshika Singh ◽  
Gaetano Cascini ◽  
Hernan Casakin ◽  
Vishal Singh
Keyword(s):  
Size Structure ◽  
Critical Role ◽  
Computational Framework ◽  
New Members ◽  
Learning Abilities ◽  
Team Members ◽  
Agent Based ◽  
Proposed Model ◽  
Dependent Parameter ◽  
The Impact

AbstractThe dynamics of design teams play a critical role in product development, mainly in the early phases of the process. This paper presents a conceptual framework of a computational model about how cognitive and social features of a design team affect the quality of the produced design outcomes. The framework is based on various cognitive and social theories grounded in literature. Agent-Based Modelling (ABM) is used as a tool to evaluate the impact of design process organization and team dynamics on the design outcome. The model describes key research parameters, including dependent, independent, and intermediates. The independent parameters include: duration of a session, number of times a session is repeated, design task and team characteristics such as size, structure, old and new members. Intermediates include: features of team members (experience, learning abilities, and importance in the team) and social influence. The dependent parameter is the task outcome, represented by creativity and accuracy. The paper aims at laying the computational foundations for validating the proposed model in the future.

scholarly journals ENVIRONMENTAL IMPACT ASSESSMENT OF HEAVY METALS EFFLUIENT (CHROMIUM & NICKEL) RELEASED INTO ROMI RIVER, KADUNA STATE: A CASE STUDY

2020 ◽  
Vol 4 (3) ◽  
pp. 704-707
Author(s):  
Muhammad Mudassir Usman ◽  
Muhammad Nuruddeen Abdulkareem ◽  
Abdullahi Muhammad ◽  
Kabiru Hamza
Keyword(s):  
Heavy Metals ◽  
Water Quality ◽  
Industrial Effluents ◽  
World Health ◽  
Refinery Effluent ◽  
Iron Nickel ◽  
The Mean ◽  
Health Organization ◽  
The Impact

Industrial effluents discharged into the river poses a serious threat to our environment; the research examines the impact of some heavy metals of Kaduna refinery effluent into the Romi River. It asserts the nature of effluent released into the water body and also the impact of effluent on water quality. However the important water quality became relatively slowly as early human could only judge water quality through the physical senses of sight, taste and smell, now a days there is an increase of contamination of natural water bodies by industrial effluents in developing and densely populated countries like Nigeria, because rivers are major means of waste disposal and especially effluents from industries nearby. The data used in this research were generated from direct field measurement of pH, Conductivity, and Turbidity, heavy metal profiles (Chromium & Nickel) from Kaduna Refinery Effluent. The mean concentrations of the metals; chromium, iron, nickel, and zinc with the standard deviation were found to be: < 0.01 ± 0.1 mg/kg, and 0.06 ± 0.1 mg/kg. This study has shown that the mean concentration of chromium and Nickel found to be lower than the World Health Organization (WHO) acceptable limits while the concentration values of nickel 0.06 ± 0.1 mg/kg and iron 0.06 ± 0.1 mg/kg as found to be higher than the WHO, acceptable limits of the metals) obtained at the effluent points and this implicate the industry adjacent to the area as one of the sources of heavy metals in the river.

scholarly journals The Impact of COVID-19 Infection on the Quality of Life of Health Care Workers

2021 ◽  
Author(s):  
Sadeel Shanshal ◽  
Harith Kh. Al-Qazaz
Keyword(s):  
Quality Of Life ◽  
Sleep Quality ◽  
Psychological Health ◽  
World Health ◽  
World Health Organization Quality ◽  
Significant Difference ◽  
Males And Females ◽  
The Mean ◽  
The Impact

Abstract Background: COVID-19 pandemic has negatively affected the entire world and one of its impacts was the increased level of stress and anxiety, especially among healthcare workers. Therefore, this study aims at evaluating the quality of life (QoL) and sleep quality of healthcare professionals in Iraq.Methods: This study assessed the QoL and sleep quality by using World Health Organization Quality of Life Instruments (WHOQOL-BREF) and the Insomnia Severity Index (ISI) respectively. The questionnaires were administered through an online cross-sectional survey targeted at workers in medical fields in Iraq from 1st to 20th of August 2021. Results: Three hundred medical health workers participated, and females constituted 75.3%. The two questionnaires had very good internal consistency. The highest scoring domain was the social relationships, followed by physical health. Significant difference was found in the mean scores of psychological health domain between males and females, with higher scores observed in males. The mean of the total ISI score was 11.58 ± 6.88 with a range between 0 and 27. Severe insomnia was observed in only 9.7% of the participants. A significant negative correlation (r = -0.118) was found between age and ISI scores of the participants. Significant differences were found between males and females with higher ISI mean score observed among males. Conclusion: The quality of life and sleep pattern can be impacted by COVID-19 infection with the psychological aspect of QoL being the most affected and some degrees of insomnia being observed in many participants.

scholarly journals Estimating the impact of interventions against COVID-19: from lockdown to vaccination

2021 ◽  
Author(s):  
James Thompson ◽  
Stephen Wattam
Keyword(s):  
Spatial Clustering ◽  
Herd Immunity ◽  
Contact Tracing ◽  
Agent Based Model ◽  
Seir Model ◽  
Agent Based ◽  
Resident Population ◽  
First Case ◽  
Equivalent Equation ◽  
The Impact

AbstractCoronavirus disease 2019 (COVID-19) is an infectious disease of humans caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since the first case was identified in China in December 2019 the disease has spread worldwide, leading to an ongoing pandemic. In this article, we present a detailed agent-based model of COVID-19 in Luxembourg, and use it to estimate the impact, on cases and deaths, of interventions including testing, contact tracing, lockdown, curfew and vaccination.Our model is based on collation, with agents performing activities and moving between locations accordingly. The model is highly heterogeneous, featuring spatial clustering, over 2000 behavioural types and a 10 minute time resolution. The model is validated against COVID-19 clinical monitoring data collected in Luxembourg in 2020.Our model predicts far fewer cases and deaths than the equivalent equation-based SEIR model. In particular, with R0 = 2.45, the SEIR model infects 87% of the resident population while our agent-based model results, on average, in only around 23% of the resident population infected. Our simulations suggest that testing and contract tracing reduce cases substantially, but are much less effective at reducing deaths. Lockdowns appear very effective although costly, while the impact of an 11pm-6am curfew is relatively small. When vaccinating against a future outbreak, our results suggest that herd immunity can be achieved at relatively low levels, with substantial levels of protection achieved with only 30% of the population immune. When vaccinating in midst of an outbreak, the challenge is more difficult. In this context, we investigate the impact of vaccine efficacy, capacity, hesitancy and strategy.We conclude that, short of a permanent lockdown, vaccination is by far the most effective way to suppress and ultimately control the spread of COVID-19.

scholarly journals Understanding the interaction between cytomegalovirus and tuberculosis in children: The way forward

2021 ◽  
Vol 17 (12) ◽  
pp. e1010061
Author(s):  
Laura Olbrich ◽  
Lisa Stockdale ◽  
Robindra Basu Roy ◽  
Rinn Song ◽  
Luka Cicin-Sain ◽  
...  
Keyword(s):  
Disease Progression ◽  
World Health ◽  
Clinical Consequence ◽  
Substantial Impact ◽  
Immunological Interactions ◽  
Tb Diagnostics ◽  
Health Organization ◽  
Study Designs ◽  
Tuberculosis In Children ◽  
The Impact

Over 1 million children develop tuberculosis (TB) each year, with a quarter dying. Multiple factors impact the risk of a child being exposed to Mycobacterium tuberculosis (Mtb), the risk of progressing to TB disease, and the risk of dying. However, an emerging body of evidence suggests that coinfection with cytomegalovirus (CMV), a ubiquitous herpes virus, impacts the host response to Mtb, potentially influencing the probability of disease progression, type of TB disease, performance of TB diagnostics, and disease outcome. It is also likely that infection with Mtb impacts CMV pathogenesis. Our current understanding of the burden of these 2 diseases in children, their immunological interactions, and the clinical consequence of coinfection is incomplete. It is also unclear how potential interventions might affect disease progression and outcome for TB or CMV. This article reviews the epidemiological, clinical, and immunological literature on CMV and TB in children and explores how the 2 pathogens interact, while also considering the impact of HIV on this relationship. It outlines areas of research uncertainty and makes practical suggestions as to potential studies that might address these gaps. Current research is hampered by inconsistent definitions, study designs, and laboratory practices, and more consistency and collaboration between researchers would lead to greater clarity. The ambitious targets outlined in the World Health Organization End TB Strategy will only be met through a better understanding of all aspects of child TB, including the substantial impact of coinfections.

scholarly journals Anatomy of digital contact tracing: role of age, transmission setting, adoption and case detection

2020 ◽  
Author(s):  
Jesús A. Moreno López ◽  
Beatriz Arregui-Garcĺa ◽  
Piotr Bentkowski ◽  
Livio Bioglio ◽  
Francesco Pinotti ◽  
...  
Keyword(s):  
Age Groups ◽  
Contact Tracing ◽  
Case Detection ◽  
Agent Based ◽  
Population Immunity ◽  
Contact Survey ◽  
Low Coverage ◽  
The Impact ◽  
Epidemiological Information

The efficacy of digital contact tracing against COVID-19 epidemic is debated: smartphone penetration is limited in many countries, non-uniform across age groups, with low coverage among elderly, the most vulnerable to SARS-CoV-2. We developed an agent-based model to precise the impact of digital contact tracing and household isolation on COVID-19 transmission. The model, calibrated on French population, integrates demographic, contact-survey and epidemiological information to describe the risk factors for exposure and transmission of COVID-19. We explored realistic levels of case detection, app adoption, population immunity and transmissibility. Assuming a reproductive ratio R=2.6 and 50% detection of clinical cases, a ~20% app adoption reduces peak incidence of ~36%. With R=1.7, >30% app adoption lowers the epidemic to manageable levels. Higher coverage among adults, playing a central role in COVID-19 transmission, yields an indirect benefit for elderly. These results may inform the inclusion of digital contact tracing within a COVID-19 response plan.

scholarly journals Obesity is associated with increased severity of disease in COVID-19 pneumonia: a systematic review and meta-analysis

2020 ◽  
Vol 25 (1) ◽  
Author(s):  
Yanan Chu ◽  
Jinxiu Yang ◽  
Jiaran Shi ◽  
Pingping Zhang ◽  
Xingxiang Wang
Keyword(s):  
Systematic Review ◽  
Hospital Mortality ◽  
Disease Progression ◽  
Fixed Effects ◽  
Data Extraction ◽  
Meta Analysis ◽  
Critical Role ◽  
Invasive Mechanical Ventilation ◽  
Poor Outcomes ◽  
The Impact

Abstract Background Obesity has been widely reported to be associated with the disease progression of coronavirus disease 2019 (COVID-19); however, some studies have reported different findings. We conducted a systematic review and meta-analysis to investigate the association between obesity and poor outcomes in patients with COVID-19 pneumonia. Methods A systematic review and meta-analysis of studies from the PubMed, Embase, and Web of Science databases from 1 November 2019 to 24 May 2020 was performed. Study quality was assessed, and data extraction was conducted. The meta-analysis was carried out using fixed-effects and random-effects models to calculate odds ratios (ORs) of several poor outcomes in obese and non-obese COVID-19 patients. Results Twenty-two studies (n = 12,591 patients) were included. Pooled analysis demonstrated that body mass index (BMI) was higher in severe/critical COVID-19 patients than in mild COVID-19 patients (MD 2.48 kg/m2, 95% CI [2.00 to 2.96 kg/m2]). Additionally, obesity in COVID-19 patients was associated with poor outcomes (OR = 1.683, 95% CI [1.408–2.011]), which comprised severe COVID-19, ICU care, invasive mechanical ventilation use, and disease progression (OR = 4.17, 95% CI [2.32–7.48]; OR = 1.57, 95% CI [1.18–2.09]; OR = 2.13, 95% CI [1.10–4.14]; OR = 1.41, 95% CI [1.26–1.58], respectively). Obesity as a risk factor was greater in younger patients (OR 3.30 vs. 1.72). However, obesity did not increase the risk of hospital mortality (OR = 0.89, 95% CI [0.32–2.51]). Conclusions As a result of a potentially critical role of obesity in determining the severity of COVID-19, it is important to collect anthropometric information for COVID-19 patients, especially the younger group. However, obesity may not be associated with hospital mortality, and efforts to understand the impact of obesity on the mortality of COVID-19 patients should be a research priority in the future.

Interventions to control nosocomial transmission of SARS-CoV-2: a modelling study

BMC Medicine ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Thi Mui Pham ◽  
Hannan Tahir ◽  
Janneke H. H. M. van de Wijgert ◽  
Bastiaan R. Van der Roest ◽  
Pauline Ellerbroek ◽  
...  
Keyword(s):  
Control Measures ◽  
Nosocomial Transmission ◽  
Sensitivity Analyses ◽  
Contact Tracing ◽  
Hospital Data ◽  
Agent Based ◽  
Effective Interventions ◽  
Maximum Test ◽  
Hospital Wards ◽  
The Impact

Abstract Background Emergence of more transmissible SARS-CoV-2 variants requires more efficient control measures to limit nosocomial transmission and maintain healthcare capacities during pandemic waves. Yet the relative importance of different strategies is unknown. Methods We developed an agent-based model and compared the impact of personal protective equipment (PPE), screening of healthcare workers (HCWs), contact tracing of symptomatic HCWs and restricting HCWs from working in multiple units (HCW cohorting) on nosocomial SARS-CoV-2 transmission. The model was fit on hospital data from the first wave in the Netherlands (February until August 2020) and assumed that HCWs used 90% effective PPE in COVID-19 wards and self-isolated at home for 7 days immediately upon symptom onset. Intervention effects on the effective reproduction number (RE), HCW absenteeism and the proportion of infected individuals among tested individuals (positivity rate) were estimated for a more transmissible variant. Results Introduction of a variant with 56% higher transmissibility increased — all other variables kept constant — RE from 0.4 to 0.65 (+ 63%) and nosocomial transmissions by 303%, mainly because of more transmissions caused by pre-symptomatic patients and HCWs. Compared to baseline, PPE use in all hospital wards (assuming 90% effectiveness) reduced RE by 85% and absenteeism by 57%. Screening HCWs every 3 days with perfect test sensitivity reduced RE by 67%, yielding a maximum test positivity rate of 5%. Screening HCWs every 3 or 7 days assuming time-varying test sensitivities reduced RE by 9% and 3%, respectively. Contact tracing reduced RE by at least 32% and achieved higher test positivity rates than screening interventions. HCW cohorting reduced RE by 5%. Sensitivity analyses show that our findings do not change significantly for 70% PPE effectiveness. For low PPE effectiveness of 50%, PPE use in all wards is less effective than screening every 3 days with perfect sensitivity but still more effective than all other interventions. Conclusions In response to the emergence of more transmissible SARS-CoV-2 variants, PPE use in all hospital wards might still be most effective in preventing nosocomial transmission. Regular screening and contact tracing of HCWs are also effective interventions but critically depend on the sensitivity of the diagnostic test used.

Sign in / Sign up

Export Citation Format

Share Document