Chang Hyuk-Jun
School of Electrical Engineering, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, 136-702, Seoul, Korea.
Biomed Eng Online. 2017 Jun 13;16(1):79. doi: 10.1186/s12938-017-0370-7.
In South Korea, an outbreak of Middle East respiratory syndrome (MERS) occurred in 2015. It was the second largest MERS outbreak. As a result of the outbreak in South Korea, 186 infections were reported, and 36 patients died. At least 16,693 people were isolated with suspicious symptoms. This paper estimates the basic reproduction number of the MERS coronavirus (CoV), using data on the spread of MERS in South Korea.
The basic reproduction number of an epidemic is defined as the average number of secondary cases that an infected subject produces over its infectious period in a susceptible and uninfected population. To estimate the basic reproduction number of the MERS-CoV, we employ data from the 2015 South Korea MERS outbreak and the susceptible-infected-removed (SIR) model, a mathematical model that uses a set of ordinary differential equations (ODEs).
We fit the model to the epidemic data of the South Korea outbreak minimizing the sum of the squared errors to identify model parameters. Also we derive the basic reproductive number as the terms of the parameters of the SIR model. Then we determine the basic reproduction number of the MERS-CoV in South Korea in 2015 as 8.0977. It is worth comparing with the basic reproductive number of the 2014 Ebola outbreak in West Africa including Guinea, Sierra Leone, and Liberia, which had values of 1.5-2.5.
There was no intervention to control the infection in the early phase of the outbreak, thus the data used here provide the best conditions to evaluate the epidemic characteristics of MERS, such as the basic reproduction number. An evaluation of basic reproduction number using epidemic data could be problematic if there are stochastic fluctuations in the early phase of the outbreak, or if the report is not accurate and there is bias in the data. Such problems are not relevant to this study because the data used here were precisely reported and verified by Korea Hospital Association.
2015年韩国爆发了中东呼吸综合征（MERS）。这是第二大MERS疫情。韩国此次疫情导致报告了186例感染病例，36名患者死亡。至少16,693人因出现可疑症状而被隔离。本文利用韩国MERS疫情传播数据估算了MERS冠状病毒（CoV）的基本再生数。
传染病的基本再生数定义为在易感且未感染人群中，一名感染个体在其传染期内产生的二代病例的平均数量。为估算MERS-CoV的基本再生数，我们采用了2015年韩国MERS疫情的数据以及易感-感染-移除（SIR）模型，这是一个使用一组常微分方程（ODEs）的数学模型。
我们将该模型与韩国疫情的流行数据进行拟合，通过最小化平方误差之和来确定模型参数。我们还将基本再生数推导为SIR模型参数的表达式。然后我们确定2015年韩国MERS-CoV的基本再生数为8.0977。值得将其与2014年在包括几内亚、塞拉利昂和利比里亚在内的西非爆发的埃博拉疫情的基本再生数进行比较，后者的值为1.5 - 2.5。
在疫情爆发的早期阶段没有采取控制感染的干预措施，因此这里使用的数据为评估MERS的流行特征（如基本再生数）提供了最佳条件。如果在疫情爆发的早期阶段存在随机波动，或者报告不准确且数据存在偏差，那么利用疫情数据评估基本再生数可能会有问题。本研究不存在此类问题，因为这里使用的数据是由韩国医院协会精确报告并核实的。
