Beijing International Center for Mathematical Research, Peking University, China.
School of Mathematical Sciences, Peking University, China.
Int J Hyg Environ Health. 2020 Jul;228:113555. doi: 10.1016/j.ijheh.2020.113555. Epub 2020 May 11.
The 2019 novel coronavirus (COVID-19) outbreak in Wuhan, China has attracted world-wide attention. As of March 31, 2020, a total of 82,631 cases of COVID-19 in China were confirmed by the National Health Commission (NHC) of China.
Three approaches, namely Poisson likelihood-based method (ML), exponential growth rate-based method (EGR) and stochastic Susceptible-Infected-Removed dynamic model-based method (SIR), were implemented to estimate the basic and controlled reproduction numbers.
A total of 198 chains of transmission together with dates of symptoms onset and 139 dates of infections were identified among 14,829 confirmed cases outside Hubei Province as reported as of March 31, 2020. Based on this information, we found that the serial interval had an average of 4.60 days with a standard deviation of 5.55 days, the incubation period had an average of 8.00 days with a standard deviation of 4.75 days and the infectious period had an average of 13.96 days with a standard deviation of 5.20 days. The estimated controlled reproduction numbers, R, produced by all three methods in all analyzed regions of China are significantly smaller compared with the basic reproduction numbers R.
The controlled reproduction number in China is much lower than one in all regions of China by now. It fell below one within 30 days from the implementations of unprecedent containment measures, which indicates that the strong measures taken by China government was effective to contain the epidemic. Nonetheless, efforts are still needed in order to end the current epidemic as imported cases from overseas pose a high risk of a second outbreak.
中国武汉发生的 2019 年新型冠状病毒（COVID-19）疫情引起了全球关注。截至 2020 年 3 月 31 日，中国国家卫生健康委员会（NHC）共确诊 COVID-19 病例 82631 例。
采用泊松似然法（ML）、指数增长率法（EGR）和随机易感感染清除动力学模型法（SIR）三种方法估计基本和控制繁殖数。
截至 2020 年 3 月 31 日，共报告了 14829 例湖北省以外确诊病例，其中共发现 198 条传播链，以及症状发作日期和 139 例感染日期。基于这些信息，我们发现序列间隔的平均值为 4.60 天，标准差为 5.55 天，潜伏期的平均值为 8.00 天，标准差为 4.75 天，传染期的平均值为 13.96 天，标准差为 5.20 天。所有三种方法在分析的中国所有地区的估计控制繁殖数 R 均明显小于基本繁殖数 R。
到目前为止，中国的控制繁殖数在所有地区都远低于 1。从采取前所未有的遏制措施之日起 30 天内，该数就降至 1 以下，这表明中国政府采取的有力措施有效地遏制了疫情。尽管如此，由于从海外输入的病例带来了二次爆发的高风险，仍需努力以结束当前的疫情。
