The effect of inter-city travel restrictions on geographical spread of COVID-19: Evidence from Wuhan, China

Billy J Quilty; Charlie Diamond; Yang Liu; Hamish Gibbs; Timothy W Russell; Christopher I Jarvis; Kiesha Prem; Carl A B Pearson; Samuel J Clifford; Stefan Flasche; Petra Klepac; Rosalind M Eggo; Mark Jit

We found that in all but one prefecture with over 7 million inhabitants, the cordon sanitaire on 23 January did not substantially change the time at which sustained transmission was likely to occur ( Figure S1 ), but the picture was more mixed in smaller cities. Of the four representative major cities selected for further analysis, during their pre-restriction travel phase in Scenario 1 (1 January -23 January, 2020): Beijing experienced a high volume of travel with approximately 1,510 (95% CI 1,200 -1,820) mean daily travellers from Wuhan; Chongqing had the highest at 1650 (95% CI 1,320 -1,970); Hangzhou received relatively fewer with 451 (95% CI 362 -541); and Shenzhen had a medium travel volume from Wuhan with 820 (95% CI 664 -976) mean daily travellers ( Figure 2A ).