剑桥大学官网刊文：新冠病毒存在三个主要变体，分别流行在不同区域

The scientists have tracked COVID-19's movement /Peter Forster, Lucy Forster, Colin Renfrew, and Michael Forster /PNAS

当地时间4月9日，来自英国和德国的研究人员在剑桥大学官网上发表关于新冠病毒的几个变种和传播路径的研究报告。

研究人员分析了自2019年12月24日至2020年3月4日期间从世界各地采集的160个完整病毒基因组数据，发现了新冠病毒的三个不同但又紧密相关的“变种”，将其分别标记为“A”、“B”和“C”。

他们发现，A类病毒与在蝙蝠和穿山甲中发现的病毒类型最为接近，研究人员称其为“疫情的根源”。B类病毒从A类经由两次突变而来，而C类又来自于B类。

研究人员进一步发现，A类病毒的变体在据称曾经在武汉居住过的美国人身上检测到，同时该病毒本身也在大量美国和澳大利亚感染者中检测到；B类是中国境内（即武汉）以及东亚地区的主要类型；C类是欧洲主要类型，在早期法国、意大利、瑞典和英国新冠肺炎患者中检测到，且在中国大陆没有发现此类型的样本。

研究人员还表示，新冠肺炎的首例感染病例和人际传播或可最早追溯至2019年9月中旬至12月初。

The COVID-19 virus has mutated as it has spread, research has found, allowing scientists to track its origins and potentially predict future trends.

What is believed to be the original strain of the virus, most closely related to that found in pangolins and bats, is termed by the scientists as "Type A." Outside China, this mutated variation is commonly found in the U.S. and Australia. Type A appears to have mutated into "Type B," which then evolved into a "Type C," which is the predominant strain found in Europe.

The scientists noticed that Type B was almost exclusively found in East Asia, leading them to question whether people living outside the region had some kind of resistance to it.

The study, conducted by scientists from the University of Cambridge, the University of Kiel, the German Institute of Forensic Genetics and Fluxus Technology and Lakeside Healthcare in the UK, can be used to create a map of the coronavirus's journey around the world.

The research was published in the Proceedings of the National Academy of Sciences.

Subsequent work, which has not been peer-reviewed, allowed the researchers to conclude that the virus's first transmission to humans was between the middle of September and early December 2019.

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