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Abstract

Background

On 20 February 2020, a locally acquired coronavirus disease (COVID-19) case was detected in Lombardy, Italy. This was the first signal of ongoing transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the country. The number of cases in Italy increased rapidly and the country became the first in Europe to experience a SARS-CoV-2 outbreak.

Aim

Our aim was to describe the epidemiology and transmission dynamics of the first COVID-19 cases in Italy amid ongoing control measures.

Methods

We analysed all RT-PCR-confirmed COVID-19 cases reported to the national integrated surveillance system until 31 March 2020. We provide a descriptive epidemiological summary and estimate the basic and net reproductive numbers by region.

Results

Of the 98,716 cases of COVID-19 analysed, 9,512 were healthcare workers. Of the 10,943 reported COVID-19-associated deaths (crude case fatality ratio: 11.1%) 49.5% occurred in cases older than 80 years. Male sex and age were independent risk factors for COVID-19 death. Estimates of R varied between 2.50 (95% confidence interval (CI): 2.18–2.83) in Tuscany and 3.00 (95% CI: 2.68–3.33) in Lazio. The net reproduction number R in northern regions started decreasing immediately after the first detection.

Conclusion

The COVID-19 outbreak in Italy showed a clustering onset similar to the one in Wuhan, China. R at 2.96 in Lombardy combined with delayed detection explains the high case load and rapid geographical spread. Overall, R in Italian regions showed early signs of decrease, with large diversity in incidence, supporting the importance of combined non-pharmacological control measures.

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/content/10.2807/1560-7917.ES.2020.25.49.2000790
2020-12-10
2024-04-18
http://instance.metastore.ingenta.com/content/10.2807/1560-7917.ES.2020.25.49.2000790
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Epidemiological characteristics of COVID-19 cases and estimates of the reproductive numbers 1 month into the epidemic, Italy, 28 January to 31 March 2020
<p class="citation"> <span>Citation style for this article:</span> <span class="meta-value authors"> <a href="/search?value1=Flavia+Riccardo&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Riccardo Flavia</a>, <a href="/search?value1=Marco+Ajelli&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Ajelli Marco</a>, <a href="/search?value1=Xanthi+D+Andrianou&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Andrianou Xanthi D</a>, <a href="/search?value1=Antonino+Bella&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Bella Antonino</a>, <a href="/search?value1=Martina+Del+Manso&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Del Manso Martina</a>, <a href="/search?value1=Massimo+Fabiani&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Fabiani Massimo</a>, <a href="/search?value1=Stefania+Bellino&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Bellino Stefania</a>, <a href="/search?value1=Stefano+Boros&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Boros Stefano</a>, <a href="/search?value1=Alberto+Mateo+Urdiales&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Urdiales Alberto Mateo</a>, <a href="/search?value1=Valentina+Marziano&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Marziano Valentina</a>, <a href="/search?value1=Maria+Cristina+Rota&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Rota Maria Cristina</a>, <a href="/search?value1=Antonietta+Filia&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Filia Antonietta</a>, <a href="/search?value1=Fortunato++D%26apos%3BAncona&option1=author&noRedirect=true" class="nonDisambigAuthorLink">D&apos;Ancona Fortunato </a>, <a href="/search?value1=Andrea+Siddu&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Siddu Andrea</a>, <a href="/search?value1=Ornella+Punzo&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Punzo Ornella</a>, <a href="/search?value1=Filippo+Trentini&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Trentini Filippo</a>, <a href="/search?value1=Giorgio+Guzzetta&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Guzzetta Giorgio</a>, <a href="/search?value1=Piero+Poletti&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Poletti Piero</a>, <a href="/search?value1=Paola+Stefanelli&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Stefanelli Paola</a>, <a href="/search?value1=Maria+Rita+Castrucci&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Castrucci Maria Rita</a>, <a href="/search?value1=Alessandra+Ciervo&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Ciervo Alessandra</a>, <a href="/search?value1=Corrado+Di+Benedetto&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Di Benedetto Corrado</a>, <a href="/search?value1=Marco+Tallon&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Tallon Marco</a>, <a href="/search?value1=Andrea+Piccioli&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Piccioli Andrea</a>, <a href="/search?value1=Silvio+Brusaferro&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Brusaferro Silvio</a>, <a href="/search?value1=Giovanni+Rezza&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Rezza Giovanni</a>, <a href="/search?value1=Stefano+Merler&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Merler Stefano</a>, <a href="/search?value1=Patrizio+Pezzotti&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Pezzotti Patrizio</a>, <a href="/search?value1=the+COVID-19+working+group&option1=author&noRedirect=true" class="nonDisambigAuthorLink">the COVID-19 working group</a></span>. Epidemiological characteristics of COVID-19 cases and estimates of the reproductive numbers 1 month into the epidemic, Italy, 28 January to 31 March 2020. <a href="/content/ecdc">Euro Surveill.</a> 2020;25(49):pii=2000790. <a href="https://doi.org/10.2807/1560-7917.ES.2020.25.49.2000790" title="doi link" target="_blank">https://doi.org/10.2807/1560-7917.ES.2020.25.49.2000790</a> <span class="ES_Article_citation"> <span class="generated">Received</span>: 03 May 2020;&nbsp;&nbsp; <span class="generated">Accepted</span>: 14 Aug 2020 </span> </p>
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