The early phase of the COVID-19 epidemic in Lombardy, Italy

• DOI: 10.1016/j.epidem.2021.100528
• Publication Date: 2021-11-20T22:27:14Z
• Authors: Danilo Cereda; Mattia Manica; Marcello Tirani; Francesca Rovida; Vittorio Demicheli; Marco Ajelli; Piero Poletti; Filippo Trentini; Giorgio Guzzetta; Valentina Marziano; Raffaella Piccarreta; Antonio Barone; Michele Magoni; Silvia Deandrea; Giulio Diurno; Massimo Lombardo; Marino Faccini; Angelo Pan; Raffaele Bruno; Elena Pariani; Giacomo Grasselli; Alessandra Piatti; Maria Gramegna; Fausto Baldanti; Alessia Melegaro; Stefano Merler
• Keywords: Basic reproduction number; Pandemic

In the night of February 20, 2020, first epidemic novel coronavirus disease (COVID-19) outside Asia was uncovered by identification its patient in Lombardy region, Italy. following weeks, experienced a sudden increase number ascertained infections and strict measures were imposed to contain spread.We analyzed official records cases occurred characterize epidemiology SARS-CoV-2 during early phase outbreak. A line list laboratory-confirmed set up later retrospectively consolidated, using standardized interviews their close contacts. We provide estimates serial interval, basic reproduction number, temporal variation net SARS-CoV-2.Epidemiological investigations detected over 500 (median age: 69, IQR: 57-78) before COVID-19 diagnosed (February 2020), suggested that already circulating at least 222 out 1506 (14.7%) municipalities with sustained transmission across all provinces. estimated mean interval be 6.6 days (95% CrI, 0.7-19). Our range from 2.6 Pavia CI, 2.1-3.2) 3.3 Milan 2.9-3.8). decreasing trend observed detection case.At time case notification, widespread entire region. This may explain large critical this region very short timeframe. The slight decrease after 2020 might due increased population awareness interventions implemented regional lockdown on March 8, 2020.