LitCovid-sentences  

PMC:7039910 / 20466-26049 JSONTXT 10 Projects

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Id Subject Object Predicate Lexical cue
T143 0-21 Sentence denotes Materials and methods
T144 23-28 Sentence denotes Model
T145 29-179 Sentence denotes We employed an infectious disease dynamics model (SEIR model) for the purpose of modeling and predicting the number of COVID-19 cases in Wuhan, China.
T146 180-408 Sentence denotes The model is a classic epidemic method to analyze the infectious disease, which has a definite latent period, and has proved to be predictive for a variety of acute infectious diseases in the past such as Ebola and SARS22,26–31.
T147 409-639 Sentence denotes Application of the mathematical model is of great guiding significance to assess the impact of isolation of symptomatic cases as well as observation of asymptomatic contact cases and to promote evidence-based decisions and policy.
T148 640-898 Sentence denotes We assumed no new transmissions from animals, no differences in individual immunity, the time-scale of the epidemic is much faster than characteristic times for demographic processes (natural birth and death), and no differences in natural births and deaths.
T149 899-1169 Sentence denotes In this model, individuals are classified into four types: susceptible (S; at risk of contracting the disease), exposed (E; infected but not yet infectious), infectious (I; capable of transmitting the disease), and removed (R; those who recover or die from the disease).
T150 1170-1230 Sentence denotes The total population size (N) is given by N = S + E + I + R.
T151 1231-1389 Sentence denotes It is assumed that susceptible individuals who have been infected first enter a latent (exposed) stage, during which they may have a low level of infectivity.
T152 1390-2275 Sentence denotes The differential equations of the SEIR model are given as:32,33\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\begin{array}{l}{\mathrm{d}}S/{\mathrm{d}}t = - {\beta}\,{S}\,{I}/{N},\\ {\mathrm{d}}E/{\mathrm{d}}t = {\beta}\,{S}\,{I}/{N} - {\sigma}\,{E},\\ {\mathrm{d}}I/{\mathrm{d}}t = {\sigma}\,{E} - {\gamma}\,{I},\\ {\mathrm{d}}R/{\mathrm{d}}t = {\gamma}\,{I},\\ {\beta} = {R}_{\mathrm{0}}{\gamma},\end{array}$$\end{document}dS∕dt=−βSI∕N,dE∕dt=βSI∕N−σE,dI∕dt=σE−γI,dR∕dt=γI,β=R0γ,where β is the transmission rate, σ is the infection rate calculated by the inverse of the mean latent period, and γ is the recovery rate calculated by the inverse of infectious period.
T153 2276-2375 Sentence denotes R software (version 3.6.2) was applied for all the calculations and estimates in the current study.
T154 2377-2413 Sentence denotes Data collection and parameter values
T155 2415-2509 Sentence denotes Estimation of the epidemic trend assuming the prevention and control measures are insufficient
T156 2510-2634 Sentence denotes We first estimated the epidemic trend in Wuhan, China assuming the current prevention and control measures are insufficient.
T157 2635-2719 Sentence denotes In this process, S was assumed to be the population of Wuhan City (11 million)15,34.
T158 2720-2834 Sentence denotes The initial assumed number of cases caused by zoonotic exposure was 40 (I) according to Imai et al.’s9 estimation.
T159 2835-2899 Sentence denotes We proposed E at 20 times of I in accordance with Read et al.13.
T160 2900-3054 Sentence denotes R was set as 0. σ was set as 1/5.2 according to the latest article by Li et al.15, which calculated the mean incubation period of COVID-19 to be 5.2 days.
T161 3055-3164 Sentence denotes Chen et al.6 calculated the average hospitalization period of 31 discharged patients to be 12.39 ± 4.77 days.
T162 3165-3331 Sentence denotes Yang et al.24 calculated the median time from disease onset to diagnosis among confirmed patients to be 5. γ was accordingly set as 1/18 (ceiling of 12.39 ± 5 is 18).
T163 3332-3449 Sentence denotes R0 was chosen based on Imai et al.’s9 estimation 2.6 (1.9–3.1) assuming 4000 (1000–9700) infections as of 18 January.
T164 3451-3543 Sentence denotes Estimation of the epidemic trend assuming the prevention and control measures are sufficient
T165 3544-3645 Sentence denotes This section discussed the scenario where the current prevention and control measures are sufficient.
T166 3646-3826 Sentence denotes The set of S, E, I, R, σ, and γ is the same as the first section except that we also explored the model with E at 30 times of I to provide a possible range of number of infections.
T167 3827-3925 Sentence denotes The absence of fever in COVID-19 cases is more frequent than in SARS-CoV and MERS-CoV infection35.
T168 3926-4035 Sentence denotes Such patients may be missed since the current surveillance case definition focused mainly on fever detection.
T169 4036-4106 Sentence denotes Accordingly, the possibility of E at 30 times of I cannot be excluded.
T170 4107-4147 Sentence denotes R0 in this section was chosen by phases.
T171 4148-4326 Sentence denotes The first phase ranges from 1 December 2019 to 23 January 2020 and can be regarded as the early phase of the epidemic when a few prevention and control measures were implemented.
T172 4327-4414 Sentence denotes R0 was set as 3.1 consistent with Imai et al.’s9 estimation of high transmission level.
T173 4415-4631 Sentence denotes On 23 January 2020, airplanes, trains, and other public transportation within the city were restricted and other prevention and control measures such as quarantine and isolation were gradually established in Wuhan20.
T174 4632-4768 Sentence denotes So, the second phase began on 24 January and Rt was set as 2.6 consistent with Imai et al.’s9 estimation of moderate transmission level.
T175 4769-4929 Sentence denotes Second February was the last day of the extended Spring Festival holiday and Chinese authorities mobilized more medical resources to support Wuhan ever since36.
T176 4930-5070 Sentence denotes The newly constructed hospital “Huoshenshan” came into service on this day37 and “Leishenshan,” mobile cabin hospitals several days later38.
T177 5071-5122 Sentence denotes Also, more and more medical teams arrived in Wuhan.
T178 5123-5252 Sentence denotes So the third phase began on 3 February and Rt was set as 1.9 consistent with Imai et al.’s9 estimation of low transmission level.
T179 5253-5329 Sentence denotes All of these measures may need one longest incubation period to take effect.
T180 5330-5583 Sentence denotes So, the last phase began on 16 February and Rt was set as 0.9 and 0.5, respectively, assuming the prevention and control measures are sufficient and effective to depict two different levels of effect of the measures in reducing transmission probability.