scholarly journals Modelling the impact of reducing control measures on the COVID-19 pandemic in a low transmission setting

2020 ◽  
Author(s):  
Nick Scott ◽  
Anna Palmer ◽  
Dominic Delport ◽  
Romesh Abeysuriya ◽  
Robyn Stuart ◽  
...  
Keyword(s):  
Public Transport ◽  
Risk Mitigation ◽  
Mitigation Strategies ◽  
Control Measures ◽  
Contact Tracing ◽  
Policy Changes ◽  
Low Transmission ◽  
Transmission Setting ◽  
Community Transmission ◽  
The Impact

AbstractAimsWe assessed COVID-19 epidemic risks associated with relaxing a set of physical distancing restrictions in the state of Victoria, Australia – a setting with low community transmission – in line with a national framework that aims to balance sequential policy relaxations with longer-term public health and economic need.MethodsAn agent-based model, Covasim, was calibrated to the local COVID-19 epidemiological and policy environment. Contact networks were modelled to capture transmission risks in households, schools and workplaces, and a variety of community spaces (e.g. public transport, parks, bars, cafes/restaurants) and activities (e.g. community or professional sports, large events). Policy changes that could prevent or reduce transmission in specific locations (e.g. opening/closing businesses) were modelled in the context of interventions that included testing, contact tracing (including via a smartphone app), and quarantine.ResultsPolicy changes leading to the gathering of large, unstructured groups with unknown individuals (e.g. bars opening, increased public transport use) posed the greatest risk, while policy changes leading to smaller, structured gatherings with known individuals (e.g. small social gatherings) posed least risk. In the model, epidemic impact following some policy changes took more than two months to occur. Model outcomes support continuation of working from home policies to reduce public transport use, and risk mitigation strategies in the context of social venues opening, such as >30% population-uptake of a contact-tracing app, physical distancing policies within venues reducing transmissibility by >40%, or patron identification records being kept to enable >60% contact tracing.ConclusionsIn a low transmission setting, care should be taken to avoid lifting sequential COVID-19 policy restrictions within short time periods, as it could take more than two months to detect the consequences of any changes. These findings have implications for other settings with low community transmission where governments are beginning to lift restrictions.

scholarly journals The Impact of Universal Mask Use on SARS-COV-2 in Victoria, Australia on the Epidemic Trajectory of COVID-19

2021 ◽  
Vol 9 ◽  
Author(s):  
Valentina Costantino ◽  
Chandini Raina MacIntyre
Keyword(s):  
Mathematical Modeling ◽  
Deterministic Model ◽  
Face Mask ◽  
Control Measures ◽  
Contact Tracing ◽  
Epidemic Size ◽  
Community Transmission ◽  
Age Structured ◽  
The Impact ◽  
Mask Effectiveness

Objective(s): To estimate the impact of universal community face mask use in Victoria, Australia along with other routine disease control measures in place.Methods: A mathematical modeling study using an age structured deterministic model for Victoria, was simulated for 123 days between 1 June 2020 and 1 October 2020, incorporating lockdown, contact tracing, and case findings with and without mask use in varied scenarios. The model tested the impact of differing scenarios of the universal use of face masks in Victoria, by timing, varying mask effectiveness, and uptake.Results: A six-week lockdown with standard control measures, but no masks, would have resulted in a large resurgence by September, following the lifting of restrictions. Mask use can substantially reduce the epidemic size, with a greater impact if at least 50% of people wear a mask which has an effectiveness of at least 40%. Early mask use averts more cases than mask usage that is only implemented closer to the peak. No mask use, with a 6-week lockdown, results in 67,636 cases and 120 deaths by 1 October 2020 if no further lockdowns are used. If mask use at 70% uptake commences on 23 July 2020, this is reduced to 7,961 cases and 42 deaths. We estimated community mask effectiveness to be 11%.Conclusion(s): Lockdown and standard control measures may not have controlled the epidemic in Victoria. Mask use can substantially improve epidemic control if its uptake is higher than 50% and if moderately effective masks are used. Early mask use should be considered in other states if community transmission is present, as this has a greater effect than later mask wearing mandates.

scholarly journals Behavior of Traffic Congestion and Public Transport in Eight Large Cities in Latin America during the COVID-19 Pandemic

2021 ◽  
Vol 11 (10) ◽  
pp. 4703
Author(s):  
Renato Andara ◽  
Jesús Ortego-Osa ◽  
Melva Inés Gómez-Caicedo ◽  
Rodrigo Ramírez-Pisco ◽  
Luis Manuel Navas-Gracia ◽  
...  
Keyword(s):  
Latin American ◽  
Public Transport ◽  
Public Transportation ◽  
Traffic Congestion ◽  
Urban Transport ◽  
Control Measures ◽  
Johns Hopkins Hospital ◽  
Large Cities ◽  
Public Data ◽  
The Impact

This comparative study analyzes the impact of the COVID-19 pandemic on motorized mobility in eight large cities of five Latin American countries. Public institutions and private organizations have made public data available for a better understanding of the contagion process of the pandemic, its impact, and the effectiveness of the implemented health control measures. In this research, data from the IDB Invest Dashboard were used for traffic congestion as well as data from the Moovit© public transport platform. For the daily cases of COVID-19 contagion, those published by Johns Hopkins Hospital University were used. The analysis period corresponds from 9 March to 30 September 2020, approximately seven months. For each city, a descriptive statistical analysis of the loss and subsequent recovery of motorized mobility was carried out, evaluated in terms of traffic congestion and urban transport through the corresponding regression models. The recovery of traffic congestion occurs earlier and faster than that of urban transport since the latter depends on the control measures imposed in each city. Public transportation does not appear to have been a determining factor in the spread of the pandemic in Latin American cities.

scholarly journals Restarting elective endoscopy safely amidst an evolving pandemic and the impact of patient perception

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Christopher Nguyen ◽  
Kevin T. Kline ◽  
Shehzad Merwat ◽  
Sheharyar Merwat ◽  
Gurinder Luthra ◽  
...  
Keyword(s):  
Risk Mitigation ◽  
Mitigation Strategies ◽  
Transmission Risk ◽  
Dynamic Monitoring ◽  
Successful Model ◽  
Outpatient Procedures ◽  
Risk Patients ◽  
Risk Mitigation Strategies ◽  
Spread Of Infection ◽  
The Impact

Abstract Background The COVID-19 pandemic has led to disruptions in elective and outpatient procedures. Guidance from the Centers for Medicare and Medicaid Services provided a framework for gradual reopening of outpatient clinical operations. As the infrastructure to restart endoscopy has been more clearly described, patient concerns regarding viral transmission during the procedure have been identified. Moreover, the efficacy of the measures in preventing transmission have not been clearly delineated. Methods We identified patients with pandemic-related procedure cancellations from 3/16/2020 to 4/20/2020. Patients were stratified into tier groups (1–4) by urgency. Procedures were performed using our hospital risk mitigation strategies to minimize transmission risk. Patients who subsequently developed symptoms or tested for COVID-19 were recorded. Results Among patients requiring emergent procedures, 57.14% could be scheduled at their originally intended interval. COVID-19 concerns represented the most common rescheduling barrier. No patients who underwent post-procedure testing were positive for COVID-19. No cases of endoscopy staff transmission were identified. Conclusions Non-COVID-19 related patient care during the pandemic is a challenging process that evolved with the spread of infection, requiring dynamic monitoring and protocol optimization. We describe our successful model for reopening endoscopy suites using a tier-based system for safe reintroduction of elective procedures while minimizing transmission to patients and staff. Important barriers included financial and transmission concerns that need to be addressed to enable the return to pre-pandemic utilization of elective endoscopic procedures.

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 Impact of public health interventions on the COVID-19 epidemic: a stochastic model based on data from an African island

2020 ◽  
Author(s):  
D. C. Nuckchady
Keyword(s):  
Stochastic Model ◽  
Population Surveillance ◽  
Health Interventions ◽  
Contact Tracing ◽  
Point Of Entry ◽  
Highly Sensitive ◽  
Travel Restrictions ◽  
Community Transmission ◽  
The Impact ◽  
Key Interventions

AbstractA stochastic model was created to simulate the impact of various healthcare measures on the COVID-19 epidemic. Travel restrictions and point of entry or exit screening help to delay the onset of the outbreak by a few weeks. Population surveillance is critical to detect the start of community transmission early and to avoid a surge in cases. Contact reduction and contact tracing are key interventions that can help to control the outbreak. To promptly curb the number of new cases, countries should diagnose patients using a highly sensitive test.

scholarly journals Protective impacts of household-based tuberculosis contact tracing are robust across endemic incidence levels and community contact patterns

2021 ◽  
Vol 17 (2) ◽  
pp. e1008713 ◽  
Author(s):  
Joshua Havumaki ◽  
Ted Cohen ◽  
Chengwei Zhai ◽  
Joel C. Miller ◽  
Seth D. Guikema ◽  
...  
Keyword(s):  
Population Level ◽  
Contact Tracing ◽  
Spatially Explicit Model ◽  
Household Transmission ◽  
Contact Patterns ◽  
Social Mixing ◽  
High Incidence ◽  
Community Transmission ◽  
The Impact ◽  
The Relationship

There is an emerging consensus that achieving global tuberculosis control targets will require more proactive case finding approaches than are currently used in high-incidence settings. Household contact tracing (HHCT), for which households of newly diagnosed cases are actively screened for additional infected individuals is a potentially efficient approach to finding new cases of tuberculosis, however randomized trials assessing the population-level effects of such interventions in settings with sustained community transmission have shown mixed results. One potential explanation for this is that household transmission is responsible for a variable proportion of population-level tuberculosis burden between settings. For example, transmission is more likely to occur in households in settings with a lower tuberculosis burden and where individuals mix preferentially in local areas, compared with settings with higher disease burden and more dispersed mixing. To better understand the relationship between endemic incidence levels, social mixing, and the impact of HHCT, we developed a spatially explicit model of coupled household and community transmission. We found that the impact of HHCT was robust across settings of varied incidence and community contact patterns. In contrast, we found that the effects of community contact tracing interventions were sensitive to community contact patterns. Our results suggest that the protective benefits of HHCT are robust and the benefits of this intervention are likely to be maintained across epidemiological settings.

scholarly journals Estimating the Impact of Control Measures to Prevent Outbreaks of COVID-19 Associated with Air Travel into a COVID-19-free country: A Simulation Modelling Study

2020 ◽  
Author(s):  
Nick Wilson ◽  
Michael G Baker ◽  
Martin Eichner
Keyword(s):  
Simulation Modelling ◽  
Air Travel ◽  
Control Measures ◽  
Contact Tracing ◽  
Uncertainty Interval ◽  
Policy Makers ◽  
Stochastic Version ◽  
Low Prevalence ◽  
And Control ◽  
The Impact

AbstractAimsWe aimed to estimate the risk of COVID-19 outbreaks associated with air travel from a country with a very low prevalence of COVID-19 infection (Australia) to a COVID-19-free country (New Zealand; [NZ]), along with the likely impact of various control measures for passengers and cabin crew.MethodsA stochastic version of the SEIR model CovidSIM v1.1, designed specifically for COVID-19 was utilized. It was populated with data for both countries and parameters for SARS-CoV-2 transmission and control measures. We assumed one Australia to NZ flight per day.ResultsWhen no interventions were in place, an outbreak of COVID-19 in NZ was estimated to occur after an average time of 1.7 years (95% uncertainty interval [UI]: 0.04-6.09). However, the combined use of exit and entry screening (symptom questionnaire and thermal camera), masks on aircraft and two PCR tests (on days 3 and 12 in NZ), combined with self-reporting of symptoms and contact tracing and mask use until the second PCR test, reduced this risk to one outbreak every 29.8 years (0.8 to 110). If no PCR testing was performed, but mask use was used by passengers up to day 15 in NZ, the risk was one outbreak every 14.1 years. However, 14 days quarantine (NZ practice in May 2020), was the most effective strategy at one outbreak every 34.1 years (0.06 to 125); albeit combined with exit screening and mask use on flights.ConclusionsPolicy-makers can require multi-layered interventions to markedly reduce the risk of importing the pandemic virus into a COVID-19-free nation via air travel. There is potential to replace 14-day quarantine with PCR testing or interventions involving mask use by passengers in NZ. However, all approaches require continuous careful management and evaluation.

scholarly journals FOREIGN INFRASTRUCTURE INVESTMENT IN DEVELOPING COUNTRIES: A DYNAMIC PANEL DATA MODEL OF POLITICAL RISK IMPACTS

2019 ◽  
Vol 25 (2) ◽  
pp. 134-167 ◽  
Author(s):  
Weiling Jiang ◽  
Igor Martek ◽  
M. Reza Hosseini ◽  
Jolanta Tamošaitienė ◽  
Chuan Chen
Keyword(s):  
Developing Countries ◽  
Foreign Direct Investment ◽  
Direct Investment ◽  
Capital Investment ◽  
Risk Mitigation ◽  
Political Risk ◽  
Dynamic Panel Data ◽  
Mitigation Strategies ◽  
Risk Indicators ◽  
The Impact

Foreign direct investment (FDI) is inhibited by political risk. Developing countries tend to experience higher levels of such risk, yet need foreign capital to generate growth. Moreover, foreign direct investment in infrastructure (FDII) – fundamental to economic growth – is particularly sensitive to political risk; characterized by high capital investment, longer investment periods, while especially exposed to mercurial shifts in government policy. Yet, no comprehensive study has been undertaken that measures the impact of political risk on FDII in developing countries. This paper addresses this lack. Twelve political risk indicators, drawn from the International Country Risk Guide Index, are used to quantify the political risk inherent to 90 developing countries, over the period 2006 to 2015. An Arellano-Bond GMM estimator is developed which measures the dollar value impact of risk on both FDI and FDII. A comparison of results confirms that FDII is generally more sensitive to risk than is FDI, however the influence of risk categories is found to vary significantly. The findings can be expected to inform infrastructure policy-makers and foreign investors alike on the dollar-impact of determinable risk levels on foreign-funded projects, and in so doing better facilitate corrective risk mitigation strategies.

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.

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