![]() ![]() ![]() As an independent validation test, we assessed the cumulative number of cases in mainland China provinces through 1 February 2020 ( Fig. The model clearly indicates that, as of 23 January 2020, the epidemic was seeded in several locations across mainland China. These results are in agreement with estimates from the combination of epidemiological and human mobility data ( 27). With a doubling time of 4 to 5 days, this level of reduction corresponds to only a modest delay (1 to 6 days) of the epidemic trajectory in mainland China. The overall reduction of infections in mainland China, excluding Wuhan, was close to 10% by 31 January 2020, with a relative reduction of infections across specific locations ranging from 1 to 58% ( Fig. The model output shows no noticeable differences in the epidemic trajectory of Wuhan but a delay of ~3 days for other locations in mainland China ( Fig. Initially, we assumed no changes in transmissibility and disease dynamics (the status quo scenario). Although the calibration obtained for different generation times provides different posterior distributions for R 0, in the early stages of the epidemic the prevalence of infections and case importations is determined by the epidemic growth rate, and the obtained results ( 12) are consistent with those reported here. The obtained values are in the same range as previous analyses based on early COVID-19 data ( 9, 20, 24– 26). The obtained posterior distribution provides an average R 0 = 2.57 and a doubling time of T d = 4.2 days (90% CI: 3.8 to 4.7 days). Here we report the results for T g = 7.5 days ( 20). Details and sensitivity analysis on all parameters are reported in the supplementary materials ( 12). We performed a sensitivity analysis by considering different combinations of average latent and infectious periods, detection rates, initial conditions, and a generation time ( T g) ranging from 6 to 11 days on the basis of plausible ranges from the SARS epidemic and recent analysis of COVID-19 data ( 16, 18– 23). Removed individuals are those who can no longer infect others (i.e., they are isolated, hospitalized, have recovered, or have died). ![]() The sum of the mean latent and infectious periods defines the generation time. Latent individuals progress to the infectious stage at a rate inversely proportional to the latent period (which we assume to have the same duration as the incubation period), and infectious individuals progress to the removed stage at a rate inversely proportional to the infectious period. Susceptible individuals can acquire the virus through contacts with individuals in the infectious category and can subsequently become latent (i.e., infected but not yet able to transmit the infection). Within each subpopulation, the human-to-human transmission of COVID-19 is modeled by using a compartmental representation of the disease in which individuals can occupy one of the following states: susceptible, latent, infectious, and removed. Mobility variations in mainland China were derived from Baidu location-based services (LBS). The airline transportation data encompass daily origin-destination traffic flows from the Official Aviation Guide (OAG) and International Air Transport Association (IATA) databases (updated in 2019), whereas ground mobility flows are derived from the analysis and modeling of data collected from the statistics offices of 30 countries on five continents ( 5). The model includes more than 3200 subpopulations in roughly 200 different countries and territories. The subpopulations are connected by the flux of individuals traveling daily among them. GLEAM uses a metapopulation network approach integrated with real-world data where the world is divided into subpopulations centered around major transportation hubs (usually airports). If you are unable to resolve a claim or dispute directly with us, you may seek the assistance of theĬanadian Transportation Agency’s website External site which may not meet accessibility guidelinesĮxternal site which may not meet accessibility guidelines.To model the international spread of the COVID-19 outbreak, we used the global epidemic and mobility model (GLEAM), an individual-based, stochastic, and spatial epidemic model ( 4– 7). Normally, a full response and explanation will be given within 30 days or as soon as reasonably possible.Ĭustomer Relations, Porter Airlines Inc., Some complaints may, however, require more time and effort to address. We review all complaints and concerns promptly and respond as quickly as reasonably possible. Please submit your written comments or complaints to our Central Baggage Department.Įmail: will receive a confirmation email that includes a case number. If you have questions or concerns about your claim, please contact our Central Baggage Department.
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