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《AnnalsofIM，2月5日，Reporting, Epidemic Growth, and Reproduction Numbers for the 2019 Novel Coronavirus (2019-nCoV) Epidemic》

  • 来源专题：COVID-19科研动态监测
  • 编译者： zhangmin
  • 发布时间：2020-02-06

  • Reporting, Epidemic Growth, and Reproduction Numbers for the 2019 Novel Coronavirus (2019-nCoV) Epidemic

    Ashleigh R Tuite , David N Fisman

    PMID: 32023340 DOI: 10.7326/M20-0358

    Background: Virologically confirmed cases of 2019 novel coronavirus (2019-nCoV) in China and other countries have increased sharply (1, 2), leading to concerns regarding its pandemic potential. Viral epidemiology has been characterized sufficiently to permit construction of transmission models that predict the future course of this epidemic (3).

    Objective: To provide insight into the changing nature of case findings and epidemic growth.

    Methods: We developed a simple disease-transmission model in which the 2019-nCoV epidemic was modeled as a branching process starting in mid-November 2019, with a serial interval of 7 days (time between cases) and a basic reproduction number (R0) of 2.3 (new cases from each old case), based on available data and assuming no intervention (Figure 1). The epidemic start date aligned our modeled case counts to point estimates from international case exportation data (4). The model estimated plausible values of the effective reproduction number (Re; reproduction number in the presence of control efforts) after implementation of a quarantine in Wuhan and surrounding areas of China on 24 January 2020 (3) (Figure 1).

  • 原文来源：https://annals.org/aim/fullarticle/2760912/reporting-epidemic-growth-reproduction-numbers-2019-novel-coronavirus-2019-ncov
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  • 《MedRixv，2月11日，Estimation of the Time-Varying Reproduction Number of 2019-nCoV Outbreak in China》
    • 来源专题：COVID-19科研动态监测
    • 编译者：xuwenwhlib
    • 发布时间：2020-02-12
    • Estimation of the Time-Varying Reproduction Number of 2019-nCoV Outbreak in China Chong You, Yuhao Deng, Wenjie Hu, Jiarui Sun, Qiushi Lin, Feng Zhou, Cheng Heng Pang, Yuan Zhang, Zhengchao Chen, XIao-Hua Zhou doi: https://doi.org/10.1101/2020.02.08.20021253 Abstract Background: The 2019-nCoV outbreak in Wuhan, China has attracted world-wide attention. As of February 5, 2020, a total of 24433 cases of novel coronavirus-infected pneumonia associated with 2019-nCov were confirmed by the National Health Commission of China. Methods: Three approaches, namely Poisson likelihood-based method (ML), exponential growth rate-based method (EGR) and stochastic Susceptible-Infected-Removed dynamic model-based method (SIR), were implemented to estimate the basic and controlled reproduction numbers. Results: A total of 71 chains of transmission together with dates of symptoms onset and 67 dates of infections were identified among 5405 confirmed cases outside Hubei as reported by February 2, 2020. Based on this information, we find the serial interval having an average of 4.41 days with a standard deviation of 3.17 days and the infectious period having an average of 10.91 days with a standard deviation of 3.95 days. Although the estimated controlled reproduction numbers R_c produced by all three methods in all different regions are significantly smaller compared with the basic reproduction numbers R_0, they are still greater than one. Conclusions: Although the controlled reproduction number is declining, it is still larger than one. Additional efforts are needed to further reduce the R_c to below one in order to end the current epidemic. *注，本文为预印本论文手稿，是未经同行评审的初步报告，其观点仅供科研同行交流，并不是结论性内容，请使用者谨慎使用.
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  • 《medRxiv，2月9日，Analysis of the epidemic growth of the early 2019-nCoV outbreak using internationally confirmed cases》
    • 来源专题：COVID-19科研动态监测
    • 编译者：zhangzx
    • 发布时间：2020-02-10
    • Analysis of the epidemic growth of the early 2019-nCoV outbreak using internationally confirmed cases Qingyuan Zhao, Yang Chen, Dylan S Small doi: https://doi.org/10.1101/2020.02.06.20020941 Abstract Background: On January 23, 2020, a quarantine was imposed on travel in and out of Wuhan, where the 2019 novel coronavirus (2019-nCoV) outbreak originated from. Previous analyses estimated the basic epidemiological parameters using symptom onset dates of the confirmed cases in Wuhan and outside China. Methods: We obtained information on the 46 coronavirus cases who traveled from Wuhan before January 23 and have been subsequently confirmed in Hong Kong, Japan, Korea, Macau, Singapore, and Taiwan as of February 5, 2020. Most cases have detailed travel history and disease progress. Compared to previous analyses, an important distinction is that we used this data to informatively simulate the infection time of each case using the symptom onset time, previously reported incubation interval, and travel history. We then fitted a simple exponential growth model with adjustment for the January 23 travel ban to the distribution of the simulated infection time. We used a Bayesian analysis with diffuse priors to quantify the uncertainty of the estimated epidemiological parameters. We performed sensitivity analysis to different choices of incubation interval and the hyperparameters in the prior specification. Results: We found that our model provides good fit to the distribution of the infection time. Assuming the travel rate to the selected countries and regions is constant over the study period, we found that the epidemic was doubling in size every 2.9 days (95% credible interval [CrI], 2 days--4.1 days). Using previously reported serial interval for 2019-nCoV, the estimated basic reproduction number is 5.7 (95% CrI, 3.4--9.2). The estimates did not change substantially if we assumed the travel rate doubled in the last 3 days before January 23, when we used previously reported incubation interval for severe acute respiratory syndrome (SARS), or when we changed the hyperparameters in our prior specification. Conclusions: Our estimated epidemiological parameters are higher than an earlier report using confirmed cases in Wuhan. This indicates the 2019-nCoV could have been spreading faster than previous estimates.
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