The effect of travel restrictions on the spread of the 2019 novel coronavirus (2019-nCoV) outbreak

Matteo Chinazzi; Jessica T. Davis; Marco Ajelli; Corrado Gioannini; Maria Litvinova; Stefano Merler; Ana Pastore y Piontti; Luca Rossi; Kaiyuan Sun; Cécile Viboud; Xinyue Xiong; Hongjie Yu; M. Elizabeth Halloran; Ira M. Longini; Alessandro Vespignani

The model allows us to estimate the number of case importations in international locations from Mainland China. We analyze how this number would increase according to projections in a fully status quo scenario compared to the presence of a travel ban. In Fig. 1C ) we report the mean number of total international importation events in the two scenarios. We find an 80% reduction in cases imported from Mainland China to other countries until the end of February. While the number of cases imported internationally initially has a marked decrease, it picks up again in the following weeks with importation from other locations in China. The model indicates that after the travel restrictions in Wuhan are implemented on January 23, the top 5 ranked cities as the origin of international case importations are Shanghai, Beijing, Shenzhen, Guangzhou, and Kunming. Similarly, the model allows ranking countries across the world according to the relative risk of importing cases from Mainland China. More precisely the relative risk is defined for each country Y , as the relative probability P (Y ) that a single infected individual travels from the index areas to that specific destination Y . In other words, given the occurrence of one exported case, P (Y ) is the relative probability that the disease carrier will appear in location Y , with respect to any 3 . CC-BY-NC-ND 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity. 4 . CC-BY-NC-ND 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.