key: cord-1043668-f9r3ge7n authors: Zhao, Zebin; Li, Xin; Liu, Feng; Zhu, Gaofeng; Ma, Chunfeng; Wang, Liangxu title: Prediction of the COVID-19 spread in African countries and implications for prevention and controls: A case study in South Africa, Egypt, Algeria, Nigeria, Senegal and Kenya date: 2020-04-25 journal: Sci Total Environ DOI: 10.1016/j.scitotenv.2020.138959 sha: b2cc35b4f97bffb860416d9b453a0b268aa69a3c doc_id: 1043668 cord_uid: f9r3ge7n Abstract COVID-19 (Corona Virus Disease 2019) is globally spreading and the international cooperation is urgently required in joint prevention and control of the epidemic. Using the Maximum-Hasting (MH) parameter estimation method and the modified Susceptible Exposed Infectious Recovered (SEIR) model, the spread of the epidemic under three intervention scenarios (suppression, mitigation, mildness) is simulated and predicted in South Africa, Egypt, and Algeria, where the epidemic situations are severe. The studies are also conducted in Nigeria, Senegal and Kenya, where the epidemic situations are growing rapidly and the socio-economic are relatively under-developed, resulting in more difficulties in preventing the epidemic. Results indicated that the epidemic can be basically controlled in late April with strict control of scenario one, manifested by the circumstance in the South Africa and Senegal. Under moderate control of scenario two, the number of infected people will increase by 1.43–1.55 times of that in scenario one, the date of the epidemic being controlled will be delayed by about 10 days, and Algeria, Nigeria, and Kenya are in accordance with this situation. In the third scenario of weak control, the epidemic will be controlled by late May, the total number of infected cases will double that in scenario two, and Egypt is in line with this prediction. In the end, a series of epidemic controlling methods are proposed, including patient quarantine, close contact tracing, population movement control, government intervention, city and county epidemic risk level classification, and medical cooperation and the Chinese assistance. J o u r n a l P r e -p r o o f 4 statistics shows that most of the cases were imported (Gilbert et al., 2020) from European countries (for example, the statistics data from February 25 to March 18: 190 input cases, 76 local cases) (https://www.afro.who.int/). Currently, the situation is still under control. However, the social-economic condition in Africa is much less-developed than other countries in the world, a series of factors, i.e., the scarcity of medical supplies, the poor medical conditions and lower virus testing efficiency would facilitate the spread of the epidemic. Additionally, the dry season of Africa is about to come, the abrupt decrease of daily mean temperature would be conducive to the spread of the disease. Consequently, the COVID-19 would probably outbreak in Africa if no strict prevention and control measures are implemented in these countries. This study aims to simulate and predict the epidemic spread in African countries under different epidemic intervention scenarios through modeling, and to propose a series of epidemic prevention and control measures, which will be crucial in containing the epidemic spread in these countries. The researches are mainly conducted in six African countries of South Africa, Egypt, Algeria, Nigeria, Senegal and Kenya. The first three countries are in severe epidemic situation already, while the situation in last three ones are in rapid deterioration with low socio-economic levels, leading to more difficulties in preventing the epidemic. denotes the number of susceptible population, represents the exposed cases, denotes the infected cases but not quarantined, is the confirmed cases and quarantined, is the recovered cases, is the dead cases, and is the unsusceptible population (protected population). These variables in total constitute the whole population. The parameters represent the protection rate (considering the intervention), infection rate, average incubation time, average quarantined time, cure rate, and mortality rate, respectively. With the laps of time, the recovery rate will increase and the mortality rate will decrease, and the adoption of interventions (such as wearing masks) will reduce the exposed significantly. Assuming the incubation period remains unchanged, the diagnosis of all cases depends on the intervention and the average quarantined time, as well as the exposed cases. The smaller the intervention factor is, the higher the infection rate is, the longer the quarantine time (Peng et al., 2020) . This requires the governments and the public to quarantine the infected cases as soon as possible. <> We estimated the corresponding parameters of SEIR, by which the epidemic of COVID-19 under different intervention scenarios are modeled. The MH parameter sampling optimization algorithm is used to estimate the parameters of the epidemic spread in each country (see Appendix A for the probability distributions of MH sampling). It is noticeable that the spatial probability distributions of the parameters samples ( Figure 2 ) in each country are very close, which may be attributed to the similar prevention and control measures were taken by African governments. The statistics were conducted from the mean, mode, median, variance, standard deviation, and skewness values respectively (see Table 2 and Appendix B for the results), which seem basically the same for each parameter. To be simplified, the mean value was adopted since it is reliable and stable for the data statistics, and can reflect the most complete information of a group of data. Journal Pre-proof J o u r n a l P r e -p r o o f 10 are used in simulation and prediction, which agreement with the current epidemic spread. The prevention and control of the epidemic are mainly reflected by the intervention factor. The sooner the epidemic is controlled, the more powerful the intervention is. Epidemic To further predict the development trends of the epidemic in these six countries, we used the parameters optimized by the MH sampling algorithm to drive the improved SEIR model. In this study, the MH parameter optimization algorithm and an improved SEIR model was used to predict the epidemic spreading trends in six African countries (South Africa, countries are likely to be quickly curbed with finite infected. Fortunately, the South Africa and Senegal are in line with this scenario. If the response speed of the governments to take prevention measures is slow and there are loopholes in the intervention measures (such as lower testing rate), the spread of the epidemic may meet the second scenario (mitigation) and the basically control time will be delayed by about 10 days by comparison with the first scenario. The results showed that Algeria, Nigeria and Kenya are adopted the palliative measures, and the curves are accord with this scenario. By comparison, the third scenario (mildness) is the worst, with the outbreak being basically contained in late May, when the number of infections doubled. Presently, the changes of the epidemic spread in Egypt is similar to the third scenario, so it is necessary to timely adjust the strategies to make the curve as close as possible to the second scenario. Besides, the epidemic will be probably uncontrolled without the rapid public health response, along with the poor awareness of the disease, insufficient prevention and control measures, and the lack of self-protection awareness. Although the relevant national departments (such as Egypt) have issued strict prevention and control measures, the containing effects on the spread of the virus are not significant according to the simulation and prediction results. Therefore, stronger, earlier interventions and a sense of public self-protection will be the essential measures to fight this disaster (John et al., 2020) . It should be pointed out that this prediction is a conservative estimate under the condition of the uncertainty of the data (such as low testing rate). traditional SEIR models, this model fully considered the quarantine status and intervention measures, and could better simulate the current confirmed cases and the future development trend of the epidemic. More importantly, the MH optimal parameter estimation algorithm is adopted based on the range of prior parameters intervals. The algorithm can estimate the corresponding reasonable parameters according to the reference values, the optimal parameters of the sampling frequency were significantly higher than that of other samples in the sampling probability space, and this sampling results can provide an accurate model parameterization to improve SEIR simulation. China has taken effective measures to curb the rapid spread of COVID-19, protecting the lives of hundreds of thousands of people (Huang and Qiao, 2020; Wang gang et al., 2020; . We suggest the relevant countries can take China's epidemic spread prevention and control as a reference, and to formulate suitable epidemic prevention and control strategies for their own countries. According to the analysis in this research, we have the following suggestions: (1) Quarantine all confirmed cases, test and track all close contacts. Due to the scarcity of medical resources in African countries, all severe cases should be strictly controlled and quarantined. Mild cases can quarantine at the hotel near hospitals and healthcare professionals should be arranged to take enhanced observations. Asymptomatic cases should also be taken seriously and quarantined for attention. All close contacts of the confirmed and asymptomatic J o u r n a l P r e -p r o o f 17 cases should be followed up and quarantined for 14 days to completely cut off the source of infection. (2) Strictly control the population flow and take personal protective measures. Strengthen border (entry quarantine), and domestic traffic control and restrict all travel issues. All individuals should be stay at home, ban all social gatherings and keep a safe social distance from each other. Prevent external input and internal spread of the virus. (3) Government intervention, rational allocation of medical supplies. The government should take strict anti-epidemic measures as soon as possible, take the overall situation into account systematically, and seriously condemns those who do not comply, such as detention, fine, etc. The government should do epidemic prevention knowledge propaganda everywhere, leave no blind spots at the same time. Security personnel shall be arranged to patrol the epidemic areas around the clock. Medical supplies should be reasonably distributed. Considering the shortage of materials in African countries, there should be enough supplies to ensure the disaster areas, other areas can be reduced appropriately, but people's protective materials (such as masks) should be able to satisfy the needs of daily life and shopping. Besides, the government should focus on the inspection rate (testing efficiency), and reasonably set up as many detection points as possible for free testing. (4) City and county epidemic risk level zones classification. All the cities and counties are divided into three levels, namely "high, medium and low" risk areas referring to China's COVID-19 prevention and control measures (http://www.nhc.gov.cn/wjw/index.shtml). J o u r n a l P r e -p r o o f 18 epidemic spread, on the other hand, restoration of normal social and economic operations in an orderly manner. Therefore, these measures can not only form the epidemic spread into an encirclement, but also the resumption of work and production of enterprises can alleviate the predicament of lack of medical supplies to some extent. (5) Expand medical cooperation between countries and regions. Actively carry out international and regional medical cooperation. Modestly learn the experience of the countries and regions where the epidemic spread is basically under control, and adjust the domestic epidemic prevention and control measures timely. Doctors and nurses in low-and medium-risk areas should fully support the worst-hit areas. (6) China maybe volunteer to suggest reasonable prevention and control measures for different countries respectively. The local epidemic spread in China has been basically controlled. The technical supports (medical teams, treatment methods), medical supplies (such as virus-detection boxes, respirators, protective clothing, and surgical masks) and other assistance should be provided by China within its power. In particular, it should be pointed out that the number of infected cases in African countries are still small at present, however, if the implementation of severe epidemic prevention measures is delayed, the model prediction will be ineffective, and then a large number of cases will emerge. The epidemic prevention and control measures will not take effect in the short term, and African society and the economy will be in a condition of depression again. Considering the rapidest increase of confirmed cases reported in Niger and Cameroon, with the accumulated confirmed cases doubled in 2.5 days by April 5 J o u r n a l P r e -p r o o f should be drawn by the corresponding governments. It is hoped that this study can provide some useful references for the epidemic prevention and control work to relevant countries and departments. We are united in our efforts to defeat the epidemic as soon as possible. The authors declare that they have no conflict of interest. Table 1 . The major estimated parameters interval of the improved SEIR model for the computational implementation of MH sampling. Preparedness and vulnerability of African countries against importations of COVID-19: a modelling study Spatiotemporal change of epidemics and its relationship with human living environments in China over the past 2200 years Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. The Lancet A data driven time-dependent transmission rate for tracking an epidemic: a case study of 2019-nCoV Looming threat of COVID-19 infection in Africa: act collectively, and fast. The Lancet J o u r n a l P r e -p r o o f