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

As with many infectious diseases, there is a risk of under reporting of cases, as some people who are infected do not seek care, some who seek care are not diagnosed and, in some settings, those who are diagnosed may not reported. There are also particular issues in an outbreak of a novel pathogen due to difficulties in mobilizing the response and in development of testing capacities, as well as changes over time in the definition of SARS-CoV-2 infection symptoms. There are therefore concerns the reported cases in countries outside of China may be an under-report of what is actually occurring. Previous work has estimated significant under reporting of COVID-19 cases in a number of countries such as Indonesia, Cambodia and Thailand. 6 A detailed understanding of the geographical distribution of case importation will help to guide resources to places with currently limited capacity to test, and provide support to perform control measures and support for clinical care.