Estimating number of global importations of COVID-19 from Wuhan, risk of transmission outside mainland China and COVID-19 introduction index between countries outside mainland China

Haoyang Sun; Borame Lee Dickens; Mark Chen; Alex Richard Cook; Hannah Eleanor Clapham

Outside of mainland China, most countries or territories we estimate as having a large number of COVID-19 cases imported from Wuhan are located in Asia (Figure 1 and Table S1 ). Outside Asia, we estimate United States, Australia, and United Kingdom as having the highest imported case count estimates (Figure 1 and Table S1 ). In addition, we also identify countries whose reported number of imported cases from Wuhan is less than the 5 th percentile of the posterior predictive distribution of our imported case estimates (Table 1) , suggesting under-detected cases imported from Wuhan in these countries or territories. In particular, we estimate that Thailand received 97 (95% CI: 66-136) imported cases from Wuhan-the largest among all the countries analyzed but have only reported ~20 cases (Table 1) . For Indonesia there have not been any reported COVID-19 cases imported from Wuhan, and yet we estimate at least 19 (95% CI: 10-30) imported cases.