A SEIR-like model with a time-dependent contagion factor describes the dynamics of the Covid-19 pandemic
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Abstract
I consider a simple, deterministic SEIR-like model without spatial or age structure, including a presymptomatic state and distinguishing between reported and nonreported infected individuals. Using a time-dependent contagion factor β ( t ) (in the form a piecewise constant function) and literature values for other epidemiological parameters, I obtain good fits to observational data for the cumulative number of confirmed cases in over 160 regions (103 countries, 24 Brazilian states and 34 U.S. counties). The evolution of β is useful for characterizing the state of the epidemic. The analysis provides insight into general trends associated with the pandemic, such as the tendency toward reduced contagion, and the fraction of the population exposed to the virus.
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SciScore for 10.1101/2020.08.06.20169557: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Table 2: Resources
No key resources detected.
Results from OddPub: Thank you for sharing your code and data.
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:While the global (cumulative) number reported cases represents a small fraction of the world population, estimates of the prevalence of unreported infections (due to asymptomatic or weakly symptomatic cases, as well as to limitations in testing) suggest total case numbers larger than reported values by a factor of five, ten …
SciScore for 10.1101/2020.08.06.20169557: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Table 2: Resources
No key resources detected.
Results from OddPub: Thank you for sharing your code and data.
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:While the global (cumulative) number reported cases represents a small fraction of the world population, estimates of the prevalence of unreported infections (due to asymptomatic or weakly symptomatic cases, as well as to limitations in testing) suggest total case numbers larger than reported values by a factor of five, ten or even more. Subject to this uncertainty, the model employed here furnishes an estimate of the exposed fraction. For the parameters employed in the present analysis, about four fifths of cases go unreported. The cumulative fraction of exposed individuals on thefinal day of the time series, etot = 1 − xf, ranges from < 0.1% to about 25%, with a strong tendency toward small fractions in highly populated regions. In particular, all regions with etot > 0.1 have populations smaller than 2 × 107; only six regions have etot > 0.2, and these have populations smaller than β × 106. The general trend is illustrated in the scatter plot of Fig. 13, which shows that larger values of etot become increasingly rare as population size N increases. A population-weighted mean over the 103 countries studied yields a mean value of . Although the restriction to regions with 2000 or more cases means that many regions are excluded, it is worth noting that the 103 included regions correspond to about 70% of the world population. Two regions with rather high values of etot (as of 12 June 2020) are New York City and Suffolk County, Massachusetts, for which the model prediction is 15...
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
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