COVID-19 Epidemic Outside China: 34 Founders and Exponential Growth

Yi Li; Meng Liang; Xianhong Yin; Xiaoyu Liu; Meng Hao; Zixin Hu; Yi Wang; Li Jin

In early December of 2019, pneumonia cases of unknown cause emerged in Wuhan, the capital of Hubei province, China. 1 A novel coronavirus (now named as COVID-19) was verified and identified as the seventh member of enveloped RNA coronavirus (subgenus sarbecovirus, Orthocoronavirinae subfamily) through high-throughput sequencing. [2] [3] [4] Human-to-human transmission in hospital and family settings had been accumulating 5-7 and has occurred among close contacts since the middle of December 2019 based on evidence from early transmission dynamics. 8 According to WHO statistics, the accumulating number of diagnosed patients in China was 78,961 in Feb 28, 2020. 9 COVID-19 raised intension not only within China but internationally. Since the first case of pneumonia caused by COVID-19 was reported from Wuhan, COVID-19 patients had rapidly been diagnosed in other cities of China and the neighboring countries including Thailand, South Korea, Japan, and even to a few Western countries. 10-12 On January13 2020, the Ministry of Public Health of Thailand reported the first imported case of lab-confirmed novel coronavirus (2019-nCoV). 13 As of Feb28 2020, cases had been reported in 52 countries and territories. The number of confirmed COVID-19 cases had reached 4,691 outside China, 9 and the number is still increasing. South Korea, the worst affected country outside China, has reported another jump. The 571 new cases brought South Korea's total confirmed cases to 2,337. A surge in cases of COVID-19 in Italy, Japan and Iran also heightened fears that the world is on the brink of a pandemic. 14 In Feb 28, WHO increased the assessment of the risk of spread and risk of impact of COVID-19 to very high at the global level.