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 generates an ensemble of possible epidemic scenarios described by the number of newly generated infections, times of disease arrival in each subpopulation, and the number of traveling infection carriers. We assume a starting date of the epidemic that falls between 11/15/2019 and 12/1/2019, with 40 cases caused by zoonotic exposure(8; 9). The posterior distribution of the basic reproductive number R 0 is estimated by exploring the likelihood of importation of 2019-nCoV cases to international locations. We have performed a sensitivity analysis considering different combinations of average latency and infectious periods, exploring a generation time (T g ) interval ranging from 6 to 11 days based on plausible ranges from the SARS epidemic and recent analysis of the 2019-nCoV data (10; 11; 12; 13; 14; 15; 16) . Details and sensitivity analysis are reported in the Supplementary Material. In the following we report the results for a generation time T g =7.5 days (12) . The obtained posterior distribution provides an average reproductive number R 0 = 2.4 [90% CI 2.2-2.6], and a doubling time measured at T d = 4.6 days [90% CI 4.2-5.1]. The obtained values are in the same range as previous analyses based on early 2019-nCoV data (12; 17; 18; 19; 20) . Although the calibration obtained for different generation times provides different posterior distributions 2 . 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.