Using simulation modelling and systems science to help contain COVID-19: A systematic review.

This study systematically reviews applications of three simulation approaches, that is, system dynamics model (SDM), agent-based model (ABM) and discrete event simulation (DES), and their hybrids in COVID-19 research and identifies theoretical and application innovations in public health. Among the 372 eligible papers, 72 focused on COVID-19 transmission dynamics, 204 evaluated both pharmaceutical and non-pharmaceutical interventions, 29 focused on the prediction of the pandemic and 67 investigated the impacts of COVID-19. ABM was used in 275 papers, followed by 54 SDM papers, 32 DES papers and 11 hybrid model papers. Evaluation and design of intervention scenarios are the most widely addressed area accounting for 55% of the four main categories, that is, the transmission of COVID-19, prediction of the pandemic, evaluation and design of intervention scenarios and societal impact assessment. The complexities in impact evaluation and intervention design demand hybrid simulation models that can simultaneously capture micro and macro aspects of the socio-economic systems involved.

Mitigating personal protective equipment (PPE) supply chain disruptions in pandemics - a system dynamics approach

Purpose The coronavirus disease (COVID-19) pandemic has emerged as an unprecedented health crisis worldwide and heavily disrupted the healthcare supply chain. This study focuses on analysing the different types of disruptions occurring in personal protective equipment (PPE) supply chains during the COVID-19 pandemic and on proposing mitigation strategies that are fit to the global scale and many interdependencies that are characteristic for this pandemic. The authors construct a conceptual system dynamics model (SD) based on the literature and adjusted with the use of empirical data (interviews) to capture the complexity of a global supply chain and identify leverage points (mitigation strategies). Design/methodology/approach This research follows a mix-methods approach. First, the authors developed a conceptual framework based on four types of disruptions that usually occur during health emergencies (direct effect, policy, supply chain strategy, and behaviourally induced disruptions). Second, the authors collected and analysed data from interviews with experts in the PPE supply chain. Based on the interviews data, the authors developed a conceptual system dynamics (SD) model that allows to capture the complex and dynamic interplay between the elements of the global supply chain system, by highlighting key feedback loops, delays, and the way the mitigation strategies can impact on them. From this analysis, the authors developed four propositions for supply chain risk management (SCRM) in global health emergencies and four recommendations for the policy and decision makers. Findings The SD model highlights that without a combination of mitigation measures, it is impossible to overcome all disruptions. As such, a co-ordinated effort across the different countries and sectors that experience the disruptions is needed. The SD model also shows that there are important feedback loops, by which initial disruptions create delays and shortages that propagate through the supply chain network. If the co-ordinated mitigation measures are not implemented early at the onset of the pandemic, these disruptions will be persistent, creating potential shortages of PPE and other critical equipment at the onset of a pandemic - when they are most urgently needed. Originality/value This research enriches the understanding of the disruptions of PPE supply chains on the systems level and proposes mitigation strategies based on empirical data and the existing literature.

The Chinese plug-in electric vehicles industry in post-COVID-19 era towards 2035: Where is the path to revival?

The sudden Coronavirus Disease reported at the end of 2019 (COVID-19) has brought huge pressure to Chinese Plug-in Electric Vehicles (PEVs) industry which is bearing heavy burden under the decreasing fiscal subsidy. If the epidemic continues to rage as the worst case, analysis based on System Dynamics Model (SDM) indicates that the whole PEVs industry in China may shrink by half compared with its originally expected level in 2035. To emerge from the recession, feasible industrial policies include (1) accelerating the construction of charging infrastructures, (2) mitigating the downtrend of financial assistance and (3) providing more traffic privilege for drivers. Extending the deadline of fiscal subsidy by only 2 years, which has been adopted by the Chinese central government, is demonstrated to achieve remarkable effect for the revival of PEVs market. By contrast, the time when providing best charging service or most traffic privilege to get the PEVs industry back to normal needs to be advanced by 10 years or earlier. For industrial policy makers, actively implementing the other two promoting measures on the basis of existing monetary support may be a more efficient strategy for Chinese PEVs market to revive from the shadow in post-COVID-19 era.

Prediction and management of household solid waste generation during COVID-19 pandemic in Bandung City using system dynamics model

WHO declared a novel coronavirus in humans as Coronavirus Disease 2019 (COVID-19) on February 2020, and Indonesia as well as Bandung City have been suffering from COVID-19 since the first case in March, 2020. Currently, the outbreak of COVID-19 has occurred for more than a year. The COVID-19 pandemic had a severe impact on the environment, like the enhancement of household solid waste as a result of work and school from home policies to decrease the rates of COVID-19 cases. This study aimed to predict the amount of household solid waste generation and analyze the waste management during COVID-19 in Bandung City using a system dynamics model. Data for model input was obtained from questionnaire to 200 respondents from Bandung spread across the sub-districts. The results revealed that the household solid waste generation was increased by 1.3 to 3.8% compared to the year before the COVID-19 pandemic. The composition of household solid waste was dominated by food and plastic waste, which have increased to 76.43% and 25.81%, respectively. The system dynamics model has predicted the household waste generation from three management scenarios for 30 years of model simulation. Scenario I: the household solid waste was totally managed by a local sanitary agency (existing condition);Scenario II: each household manage their waste by recycling;and Scenario III: the utilization of a local waste bank to manage the waste. The scenario III showed the most effective waste management to reduce the amount of household solid waste generation up to 24% by using waste bank. This scenario can be applied for more prolonged landfill operations up to 17 years.

A study on the impact of extreme weather events on the ceramic manufacturing in Egypt

Nowadays, global economic production is organized around a complex system of highly interdependent supply chains that are currently enormously disrupted due to COVID 19. What would happen if a fast-growing risk could pose a more significant threat to our supply chains? Are our supply chains resilient to climate change? Even though governments, businesses, and climate change organizations in developed countries are forced to work together trying to mitigate and adapt to this fast-moving phenomenon, developing countries like Egypt are less concerned about this topic. This study has developed a system dynamic model based on a four-phase mixed methodology approach;we captured the complex interconnected interactions between supply chain performance and climate change physical risks. A cognitive map was first developed to capture the relationship between the climate change physical risks variables and the supply chains. Then, historical climate data and data from a ceramic manufacturing company were analyzed using the Statistical Package for the Social Sciences (SPSS). A case study of a ceramic manufacturing company located in Egypt is provided to show the applicability of our developed system dynamic model. Lastly, we simulated different scenarios to assess the ramifications and consequences of climate change extreme weather-related events on the manufacturing process of the selected case company. We have observed a negative impact;a decrease in the manufacturing inventory level and production rate, total received orders and sales. As far as our knowledge, our study is the first to investigate the impacts of climate change extreme weather events on supply chains located in Egypt. Our main contribution is to prove and establish awareness among business owners, organizations, decision-makers and the Egyptian government that climate change and related extreme weather events exist and disruptions due to this fast-moving phenomenon must be considered.

Overcoming COVID-19 in China despite shortcomings of the public health system: what can we learn?

BACKGROUND AND OBJECTIVE: The COVID-19 pandemic started in Wuhan, China, in December 2019. Although there are some doubts about the reporting of cases and deaths in China, it seems that this country was able to control the epidemic more effectively than many other countries. In this paper, we would like to analyze the measures taken in China and compare them with other countries in order to find out what they can learn from China. METHODS: We develop a system dynamics model of the COVID-19 pandemic in Wuhan. Based on a number of simulations we analyze the impact of changing parameters, such as contact rates, on the development of a second wave. RESULTS: Although China's health care system seems to be poorly financed and inefficient, the epidemic was brought under control in a comparably short period of time and no second wave was experienced in Wuhan until today. The measures to contain the epidemic do not differ from what was implemented in other countries, but China applied them very early and rigorously. For instance, the consequent implementation of health codes and contact-tracking technology contributed to contain the disease and effectively prevented the second and third waves. CONCLUSIONS: China's success in fighting COVID-19 is based on a very strict implementation of a set of measures, including digital management. While other countries discuss relaxing the lock-down at a rate of 50 per 100,000 inhabitants, China started local lock-downs at a rate of 3 per 100,000. We call for a public debate whether this policy would be feasible for more liberal countries as well.

Exploring early prevention and control of COVID-19 outbreak based on system dynamics model analysis.

To explore early prevention and control of coronavirus disease 2019 （COVID-19） outbreak based on system dynamics model analysis. The data of early outbreak of COVID-19 were collected from the World Health Organization，covering countries of the China，United States，United Kingdom，Australia，Serbia and Italy. The susceptible-exposed-infected-recovered （SEIR） model was generalized and then its parameters were optimized. According to the parameters in the basic infection number expression，the sensitivity in the system dynamics model was used to quantitatively analyze the influence of the protection rate，infection rate and average quarantine time on the early spread of the outbreak. Based on the analysis results，targeted prevention and control measures for the early outbreak of COVID-19 were proposed. The generalized SEIR model had a good fit for the early prediction and evaluation of COVID-19 outbreaks in six countries. The spread of COVID-19 was mainly affected by the protection rate，infection rate and average quarantine time. The improvement of the protection rate in the first ays was the most important:the greater the protection rate，the fewer the number of confirmed cases. The infection rate in the first 5 days was the most critical:the smaller the infection rate，the fewer the number of confirmed cases. The average quarantine time in the first 5 days was very important:the shorter the average quarantine time，the fewer the number of confirmed cases. Through the comparison of key parameters of six countries，Australia and China had implemented strict epidemic prevention policies，which had resulted in good epidemic prevention effects. In the early stage of the outbreak，it is necessary to improve the protection rate，shorten the average quarantine time，and implement strict isolation policies to curb the spread of COVID-19.