The early phase of the COVID-19 outbreak in Lombardy, Italy
D Cereda, M Tirani, F Rovida, V Demicheli, M Ajelli, P Poletti, F, Trentini, G Guzzetta, V Marziano, A Barone, M Magoni, S Deandrea, G Diurno, M, Lombardo, M Faccini, A Pan, R Bruno, E Pariani, G Grasselli, A Piatti, M, Gramegna, F Baldanti, A Melegaro, S Merler

TL;DR
This study characterizes the early COVID-19 outbreak in Lombardy, Italy, revealing rapid spread, high transmission potential, and the urgent need for containment strategies to prevent healthcare system overload.
Contribution
It provides the first detailed epidemiological analysis of COVID-19 in a Western country, including estimates of reproduction number and serial interval, and highlights the early undetected spread.
Findings
Median age of cases is 69 years.
Estimated basic reproduction number is 3.1.
Serial interval is approximately 6.6 days.
Abstract
In the night of February 20, 2020, the first case of novel coronavirus disease (COVID-19) was confirmed in the Lombardy Region, Italy. In the week that followed, Lombardy experienced a very rapid increase in the number of cases. We analyzed the first 5,830 laboratory-confirmed cases to provide the first epidemiological characterization of a COVID-19 outbreak in a Western Country. Epidemiological data were collected through standardized interviews of confirmed cases and their close contacts. We collected demographic backgrounds, dates of symptom onset, clinical features, respiratory tract specimen results, hospitalization, contact tracing. We provide estimates of the reproduction number and serial interval. The epidemic in Italy started much earlier than February 20, 2020. At the time of detection of the first COVID-19 case, the epidemic had already spread in most municipalities of…
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Taxonomy
TopicsCOVID-19 epidemiological studies · COVID-19 diagnosis using AI · COVID-19 Pandemic Impacts
