Lessons learnt from 288 COVID-19 international cases: importations over time, effect of interventions, underdetection of imported cases

Francesco Pinotti; Laura Di Domenico; Ernesto Ortega; Marco Mancastroppa; Giulia Pullano; Eugenio Valdano; Pierre-Yves Boelle; Chiara Poletto; Vittoria Colizza

We reviewed here all confirmed cases out of China from January 3 to February 13, 2020 and gathered detailed information on case history and epidemiological links. We identified salient epidemiological features, and modeled the number of importations over time. International exportations from Hubei grew rapidly, fueled by the local epidemic, up to the closure of Wuhan airport preventing further travel of cases. Exportations from other Chinese provinces and other countries grew at a considerably slower pace. This is related to the difference in the increase of cases between Hubei province, origin of the outbreak, and the rest of the affected areas 1 . Such difference is likely an outcome of the implementation of containment measures in China 3,20,21 , and of the increased awareness at different phases of the outbreak 22-26 (i.e. before and after containment measures) leading to self-isolation and quarantine.