ABSTRACT
The cumulative number of confirmed cases in the United States exceeded one million on 29 April 2020, becoming the country of the most serious pandemic in the world. We proposed a model to analyze the real situation and follow-up trend of the epidemic in the US. The proposed model divides the epidemic period into two phases, and includes three different categories of transmitters: the latent population, the documented infectious population, and the undocumented infectious population. We use metapopulation network to simulate the spread of the COVID-19 in the US, and apply the Bayesian inference to estimate the key parameters of the model. We also perform component analysis and sensitivity analysis, researching the compositions of the people with COVID-19. The results show that the basic reproduction number in the early period of propagation is 4.06. As of April 13, 2020, only 45% (95% CI: 35% - 73%) of symptom onset cases in the United States were documented. The incubation period of COVID-19 is 10.69 days (95% CI: 10.02 - 11.74). If the current level of interventions is continued, the cumulative number of confirmed cases is expected to reach more than 1.7 million in July and continue to grow.
ABSTRACT
COVID-19 is now widely spreading around the world as a global pandemic. In this report, we estimated the global tendency of COVID-19 and analyzed the associated global epidemic risk, given that the status quo is continued without further measures being taken. Based on official data of confirmed and recovered cases until May 21, 2020, the results showed that the global R0, excluding China, was estimated to be 2.76 (95% CI: 2.57 - 2.95). The United States, Germany, Italy, and Spain have peak values over 100,000. Using dynamical model and cluster analysis, we partition the globe into four regional epicenters of the outbreak: Southeast Asia extending southward to Oceania, the Middle East, Western Europe, and North America. Among them, Western Europe would become the major center of the outbreak. The peak values in Germany, Italy, and Spain were estimated to be 228,000, 291,000, and 298,000, respectively. Based on the current control measures by May 21, 2020, the peak value in the United States will reach 2,114,000. The cumulative number of 51 mainly researched countries patients might finally attain 6,542,000 (95% CI: 4,772,000 - 40,735,000). We also estimated the diagnosis rate, recovery rate, and infection degree of each country or region, and used clustering algorithm to retrieve countries or regions with similar epidemic characteristics. Several suggestions have been proposed for countries or regions in different clusters.
ABSTRACT
BackgroundSince the 2019-nCoV (COVID-19) outbreaks in Wuhan, China, the cumulative number of confirmed cases is increasing every day, and a large number of populations all over the world are at risk. The quarantine and traffic blockage can alleviate the risk of the epidemic and the infections, henceforth evaluating the efficacy of such actions is essential to inform policy makers and raise the public awareness of the importance of self-isolation and quarantine. MethodWe collected confirmed case data and the migration data, and introduced the quarantine factor and traffic blockage factor to the Flow-SEIR model. By varying the quarantine factor and traffic blockage factor, we simulated the change of the peak number and arrival time of infections, then the efficacy of these two intervation measures can be analyzed in our simulation. In our study, the self-protection at home is also included in quarantine. ResultsIn the simulated results, the quarantine and traffic blockage are effective for epidemic control. For Hubei province, the current quarantine factor is estimaed to be 0.405, which means around 40.5% of suceptibles who are close contacting with are in quarantine, and the current traffic blockage factor is estimaed to be 0.66, which indicates around 34% of suceptibles who had flowed out from Hubei. For the other provinces outside Hubei, the current quarantine factor is estimated to be 0.285, and the current traffic blockage factor is estimated to be 0.26. With the quarantine and traffic blockage factor increasing, the number of infections decrease dramatically. We also simulated the start dates of quarantine and traffic blockage at four time points, the simulated results show that the early of warning is also effective for epidemic containing. However, provincial level traffic blockage can only alleviate 21.06% - 22.38% of the peak number of infections. In general, the quarantine is much more effective than the traffic blockage control. ConclusionBoth of quarantine and traffic blockage are effective ways to control the spread of COVID-19. However, the eff icacy of quarantine is found to be much stronger than that of traffic blockage. Considering traffic blockage may also cause huge losses of economy, we propose to gradually deregulate the traffic blockage, and improve quarantine instead. Also, there might be a large number of asymptomatic carriers of COVID-19, the quarantine should be continued for a long time until the epidemic is totally under control.
ABSTRACT
Since December 1, 2019, the spread of COVID-19 is increasing every day. It is particularly important to predict the trend of the epidemic for the timely adjustment of the economy and industries. We proposed a Flow-SEHIR model in this paper to perform the trends of 2019-nCoV (COVID-19) in China. The results show that the number of daily confirmed new cases reaches the inflection point on Feb. 6 - 10 outside Hubei. For the maximum of temporal infected cases number, the predicted peak value in China except Hubei was estimated to be 21721 (95% CI: 18764 - 24929). The peak arrival time is on March 3 - 9. The temporal number of patients in most areas of China outside Hubei will peak from March 12 to March 15. The peak values of more than 73.5% provinces or regions in China will be controlled within 1000. According to Flow-SEHIR model and estimations from the data of evacuation of nationals from Wuhan, the real peak cumulative number of patients in Hubei is estimated to be 403481 (95% CI: 143284 - 1166936).
