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nCoV Reporting and Control

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posted on 03.02.2020 by David Fisman, Ashleigh Tuite
The figure shows outputs from an R-Shiny tool that simulates the initial dynamics of the 2019-nCoV outbreak worldwide. The initial growth of the epidemic is based on introduction of the pathogen in mid-November 2019, with R_0 = 2.3 and a serial interval of 7 days. It can be seen that the model reproduces MRC/Imperial College estimates of case counts based on volume of internationally-exported cases (green squares). Daily cumulative counts of virologically confirmed cases are based on estimates published at https://bnonews.com/index.php/2020/02/the-latest-coronavirus-cases/ (blue circles).

It can be seen that under-reporting of cases, as compared to model estimates, decreases over time, as reported counts converge with model counts. Furthermore, lags in reporting (horizontal distance between model estimates and case counts for a given count) decrease over time.

In this iteration of the model, control is implemented on January 24, 2020, the day full quarantine was imposed in Wuhan, and control measures were implemented throughout China. It can be seen that reported counts as of February 3 are not compatible with reduction of average reproduction number to 1.0 during that interval (orange curve) but may be compatible with reduction to 1.5 (yellow curve), as reported case counts do not exceed modeled counts. Higher reproduction numbers with under-reporting are still possible.

If control is achieved, reported case counts will intersect horizontally with the contour lines on this graph. When reported cases move beyond contours vertically, the reproduction numbers represented by those contours become implausible.

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