Estimation of COVID-19 outbreak size in Italy based on international case exportations

Italy is currently experiencing an epidemic of COVID-19 which emerged in the Lombardy region ¹ . During the interval between February 25-29, 2020, we identified 46 cases of COVID-19 reported in 21 countries in Europe, Africa, North America, and South America which were either in individuals with recent travel from Italy, or who had presumed infection by a traveler from Italy ² . In six cases, in four of the affected countries (Switzerland, France, Austria, Croatia), land travel was a likely route of introduction, or was documented to have been the route of introduction ² .