key: cord-0736309-5qupha9z
authors: Zhuang, Zian; Zhao, Shi; Lin, Qianying; Cao, Peihua; Lou, Yijun; Yang, Lin; Yang, Shu; He, Daihai; Xiao, Li
title: Preliminary estimating the reproduction number of the coronavirus disease (COVID-19) outbreak in Republic of Korea and Italy by 5 March 2020
date: 2020-04-22
journal: International Journal of Infectious Diseases
DOI: 10.1016/j.ijid.2020.04.044
sha: 5177749282d001a3bf94bc03c43e995ad8066bad
doc_id: 736309
cord_uid: 5qupha9z

Abstract The novel coronavirus disease 2019 (COVID-19) outbreak and Italy has caused 6088 cases and 41 deaths in Republic of Korea and 3144 cases and 107 death in Italy by 5 March 2020. We modeled the transmission process in Republic of Korea and Italy with a stochastic model and estimated the basic reproduction number R 0 as 2.6 (95% CI: 2.3-2.9) or 3.2 (95% CI: 2.9-3.5) in Republic of Korea, under the assumption that the exponential growth starting on 31 January or 5 February 2020, and 2.6 (95% CI: 2.3-2.9) or 3.3 (95% CI: 3.0-3.6) in Italy, under the assumption that the exponential growth starting on 5 February or 10 February 2020.

March 2020. We modeled the transmission process in Republic of Korea and Italy 28 with a stochastic model and estimated the basic reproduction number R 0 as 2.6 (95% 29 CI: 2.3-2.9) or 3.2 (95% CI: 2.9-3.5) in Republic of Korea, under the assumption that 30 the exponential growth starting on 31 January or 5 February 2020, and 2.6 (95% CI: 31 2.3-2.9) or 3.3 (95% CI: 3.0-3.6) in Italy, under the assumption that the exponential 32 growth starting on 5 February or 10 February 2020. An evaluation version of novaPDF was used to create this PDF file. Purchase a license to generate PDF files without this notice.

The coronavirus disease 2019 (COVID-19) first emerged in Wuhan, China in the end 42 of 2019 and spread to more than 60 foreign countries as of 1 March 2020 [1] . On 20 43 January 2020, the first imported COVID-19 case was detected in Republic of Korea, 44 and the epidemic curve appeared steadily until 15 February. In the second half of 45

February, the number of reported cases increased rapidly with more than 1200 cases a 46

week. As of 5 March 2020, there were 6088 cases confirmed including 41 deaths [1] . 47

In Italy, the first case was reported on 6 February 2020 and the epidemic curve was The onset date of each secondary case is the summation of the onset date of the 65 primary case (t) plus the serial interval (SI). In this work, the SI was assumed as a 66

Gamma distribution with a 4.5-day mean and a 3.1-day standard deviation (SD) [3] [4] [5] . 67

The transmission process was simulated stochastically. 68 69 An evaluation version of novaPDF was used to create this PDF file. Purchase a license to generate PDF files without this notice. outbreak in January 2020, we consider the sustaining exponential growth might start  5 February and 10 February 2020 for Italy 74 with one seed infection. The R 0 was estimated by the maximum likelihood estimates 75 approach that fit the reported cases with Poisson-distributed likelihood framework as 76 follows. 77

.

(1) 78

Here, the l(•) is the overall log-likelihood and T is the total number of days since the 79 start of exponential growth. The n t represents number of cases reported on t-th day. 80

We calculated 95% confidence intervals (95%CI) by using the profile likelihood 81 estimation approach determined by a Chi-square quantile. 82 83

In Table 1 , we estimated the R 0 in Republic of Korea at 2.6 (95% CI: 2.3−2.9) and 3.2 86 (95% CI: 2.9−3.5) with the transmission starting date on 31 January and 5 February 87 2020, and the R 0 in Italy at 2.6 (95% CI: 2.3-2.9) and 3.3 (95% CI: 3.0-3.6), with the 88 transmission starting date on 5 February and 10 February 2020. In the supplementary Fig S2, 

Open-source analytics tools for studying the 164

Ebola superspreading. The Lancet Infectious Diseases

Estimating the serial interval of the novel coronavirus 170 disease (COVID-19): A statistical analysis using the public data in Hong Kong 171 from

The serial interval 175 of COVID-19 from publicly reported confirmed cases

Serial interval of novel 179 coronavirus (2019-nCoV) infections

COVID-19 in Republic of Korea. medRxiv 2020

Preliminary estimation of the basic reproduction number 187 of novel coronavirus (2019-nCoV) in China

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Half of Republic of Korea's coronavirus cases are linked to a controversial 191 religious organization

Italian town shows zest for history with 'Battle of the Oranges' food fight

A new framework and 199 software to estimate time-varying reproduction numbers during 200 epidemics

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All data and materials used in this work were publicly available. 137

Not applicable. 

None. 145

The funding agencies had no role in the design and conduct of the study; collection, 147 management, analysis, and interpretation of the data; preparation, review, or approval 148 of the manuscript; or decision to submit the manuscript for publication. 149

Collaborative Research project. Other authors declare no competing interests. 152

All authors conceived the study, carried out the analysis, discussed the results, drafted 154 the first manuscript, critically read and revised the manuscript, and gave final 155 approval for publication. 156