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. 2020 Apr:93:339-344.
doi: 10.1016/j.ijid.2020.03.031. Epub 2020 Mar 18.

Transmission potential and severity of COVID-19 in South Korea

Eunha Shim  1 , Amna Tariq  2 , Wongyeong Choi  3 , Yiseul Lee  4 , Gerardo Chowell  5
Affiliations

Transmission potential and severity of COVID-19 in South Korea

Eunha Shim et al. Int J Infect Dis. 2020 Apr.

Abstract

Objectives: Since the first case of 2019 novel coronavirus (COVID-19) identified on Jan 20, 2020, in South Korea, the number of cases rapidly increased, resulting in 6284 cases including 42 deaths as of Mar 6, 2020. To examine the growth rate of the outbreak, we present the first study to report the reproduction number of COVID-19 in South Korea.

Methods: The daily confirmed cases of COVID-19 in South Korea were extracted from publicly available sources. By using the empirical reporting delay distribution and simulating the generalized growth model, we estimated the effective reproduction number based on the discretized probability distribution of the generation interval.

Results: We identified four major clusters and estimated the reproduction number at 1.5 (95% CI: 1.4-1.6). In addition, the intrinsic growth rate was estimated at 0.6 (95% CI: 0.6, 0.7), and the scaling of growth parameter was estimated at 0.8 (95% CI: 0.7, 0.8), indicating sub-exponential growth dynamics of COVID-19. The crude case fatality rate is higher among males (1.1%) compared to females (0.4%) and increases with older age.

Conclusions: Our results indicate an early sustained transmission of COVID-19 in South Korea and support the implementation of social distancing measures to rapidly control the outbreak.

Keywords: COVID-19; Coronavirus; Korea; Reproduction number.

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Figures

Figure 1
Figure 1
Reconstructed epidemic curve for the local Korean COVID-19 cases by the dates of onset as of February 26, 2020. The blue triangles represent the local cases, red triangles represent the imported cases and the gray curves correspond to the uncertainty in the local cases because of missing onset dates.
Figure 2
Figure 2
The mean reproduction number with 95% CI estimated by adjusting for the imported cases with α = 0.15. Estimates for growth rate (r) and the scaling of the growth rate parameter (p) are also provided. The plot at the bottom depicts the fit of the Generalized Growth Model to the Korean data assuming Poisson error structure as of February 26, 2020.
Figure 3
Figure 3
Map depicting the spatial distribution of the four largest clusters of COVID-19 in Korea as of March 8, 2020.
See this image and copyright information in PMC

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