据位于纽约的“西奈山伊坎医学院”(Icahn School of Medicine at Mount Sinai)和纽约大学医学院分别进行的最新基因研究表明，新冠病毒早在2月中旬就开始在纽约地区传播，也就是说，在纽约第一个确诊病例出现前的几周，主要是来自欧洲的旅行者带来了这种病毒，而不是来自亚洲的旅行者。
看看作者的官网解释：
https://www.cam.ac.uk/research/news/covid-19-genetic-network-analysis-provides-snapshot-of-pandemic-origins?from=singlemessage&isappinstalled=0
“ Study charts the “incipient supernova” of COVID-19 through genetic mutations as it spread from China and Asia to Australia, Europe and North America. Researchers say their methods could be used to help identify undocumented infection sources. ”
从中国亚洲散布到世界的哈。
跟上次意大利科学家发表文章一样。人家一直澄清他们科研发现是从11月新冠就从武汉传到了意大利。
结果大陆媒体自顾自一个劲的说，科学家发现意大利11月就有新冠。
科学家如果证实病毒来源是美国，一定会明说，一定会写标题里。想通过同行审阅不能有阴谋论的脑回路。一切只能基于证据。
“There are two subclusters of A which are distinguished by the synonymous mutation T29095C. In the T-allele subcluster, four Chinese individuals (from the southern coastal Chinese province of Guangdong) carry the ancestral genome, while three Japanese and two American patients differ from it by a number of mutations. These American patients are reported to have had a history of residence in the presumed source of the outbreak in Wuhan. ”
专门去PNAS上去看一下。根据中国的病毒来源假设，即病毒来源于一种来自云南的蝙蝠（同源性96.2)，于其最近基因序列为A。A有两个分组，区别就在于一个基因突变。第一组，来自中国广东，第二组是三个日本人和两个美国人。日本人的情况没有提，美国人有武汉居住史。
原文：“There are two subclusters of A which are distinguished by the synonymous mutation T29095C. In the T-allele subcluster, four Chinese individuals (from the southern coastal Chinese province of Guangdong) carry the ancestral genome, while three Japanese and two American patients differ from it by a number of mutations. These American patients are reported to have had a history of residence in the presumed source of the outbreak in Wuhan. The C-allele subcluster sports relatively long mutational branches and includes five individuals from Wuhan, two of which are represented in the ancestral node, and eight other East Asians from China and adjacent countries. It is noteworthy that nearly half (15/33) of the types in this subcluster, however, are found outside East Asia, mainly in the United States and Australia.”
直译：
A株有两种子类，一种叫T，一种叫C。T类里面的上游在四个中国人身上发现，T也在3个日本人，2个美国人身上发现，他们都在武汉居住过。C类有5例武汉的病毒，包括2例被认为是C类中的上游。中国之外的亚洲也有8例。亚洲之外有15/33例，大部分是美国或者澳大利亚。
Forster and colleagues found that the closest type of COVID-19 to the one discovered in bats – type ‘A’, the “original human virus genome” – was present in Wuhan, but surprisingly was not the city’s predominant virus type.
Mutated versions of ‘A’ were seen in Americans reported to have lived in Wuhan, and a large number of A-type viruses were found in patients from the US and Australia.
翻译是在装傻吗？还是故意没有准确翻译？
:
无毛阉狗真不是一般的不要脸，学口交部赵立贱学出了新高度哈。
颠倒黑白，是不是以为别人也像你一样不懂英语不读原文？下面是原文摘要里的原话
The A and C types are found in significant proportions outside East Asia, that is, in Europeans and Americans. In contrast, the B type is the most common type in East Asia, and its ancestral genome appears not to have spread outside East Asia without first mutating into derived B types, pointing to founder effects or immunological or environmental resistance against this type outside Asia.
懂不懂什么叫“pointing to founder effects or immunological or environmental resistance against this type outside Asia.”？
来，无毛阉狗，再来读读这段，啪啪啪地打你的逼脸啊。
One practical application of the phylogenetic network is to reconstruct infection paths where they are unknown and pose a public health risk. The following cases where the infection history is well documented may serve as illustrations (SI Appendix). On 25 February 2020, the first Brazilian was reported to have been infected following a visit to Italy, and the network algorithm reflects this with a mutational link between an Italian and his Brazilian viral genome in cluster C (SI Appendix, Fig. S1). In another case, a man from Ontario had traveled from Wuhan in central China to Guangdong in southern China and then returned to Canada, where he fell ill and was conclusively diagnosed with coronavirus disease 2019 (COVID-19) on 27 January 2020. In the phylogenetic network (SI Appendix, Fig. S2), his virus genome branches from a reconstructed ancestral node, with derived virus variants in Foshan and Shenzhen (both in Guangdong province), in agreement with his travel history. His virus genome now coexists with those of other infected North Americans (one Canadian and two Californians) who evidently share a common viral genealogy. The case of the single Mexican viral genome in the network is a documented infection diagnosed on 28 February 2020 in a Mexi
一场突如其来的疫情打乱了人们原本的生活节奏，目前COVID-19已成为全球大流行。而自疫情发生以来，关于“病毒从哪里来”的追问就没有停止过。
最近，剑桥大学研究人员发表在《美国科学院院刊》(PANS)上一篇针对新冠病毒溯源的研究发现，目前全球感染的新冠病毒实际上并非是同一种，而是变异分化成A、B、C三种类型，并且这三种类型的病毒在全球分布范围不同。
研究人员通过绘制2019年12月至今年3月新冠病毒的基因发展史，发现了上述三种不同但又密切相关的病毒类型;然后通过在全球范围内收集的160份感染样本发现了不同类型的新冠病毒在全球传播的轨迹。
让人比较意外的是，A型--最原始的毒株，被认为是从蝙蝠传播到人类中的新冠病毒祖先--虽然最先在中国被发现，但却在美国最为普遍。研究发现有三分之二的美国样本感染A型病毒，但其中受感染的患者大多数来自西海岸，而非纽约--纽约目前为美国疫情的“震中”。
而至于B型--被认为是经过A型在中国变异而来的--则在东亚最为普遍。在93个感染B型的样本中，除19个外，其他全部分布在中国或与中国邻近的亚洲国家。具体来看，武汉样本为22个，中国东部及其他地区为31个，与中国邻近的亚洲国家发现21个。
虽然目前关于B型为何在中国最为普遍的原因还没找到答案，但研究人员猜测可能是由于B型最能攻击中国人免疫力，因此不需要变异。
最后C型--被认为是由B型衍生而来，在中国大陆样本中不存在，但却在欧洲非常普遍。研究人员认为它可能是通过新加坡传播的。
（图片来源：论文《Phylogenetic network analysis of SARS-CoV-2 genomes》）
综合上述结论，研究人员认为，为了精准攻击不同人群的免疫系统，新冠病毒正在不断发生变异。该研究可以帮助预测未来全球疫情传播和激增的热点。
不过，尽管上述研究成果得到了同行评审，但是由于它分析的样本较小——仅追踪了全球160名患者的样本，是否具有普遍性还不得而知。为了弥补这一局限，目前该研究团队已经更新了他们的数据，纳入了截至到3月底1000多例的COVID-19病例（该样本未得到同行评审）。
纽约疫情存多条传播链，但主要来自欧洲
此外，针对为何纽约感染病毒的情况与美国西海岸不同，另外两项研究给出了答案。
据位于纽约的“西奈山伊坎医学院”(Icahn School of Medicine at Mount Sinai)和纽约大学医学院分别进行的最新基因研究表明，新冠病毒早在2月中旬就开始在纽约地区传播，也就是说，在纽约第一个确诊病例出现前的几周，主要是来自欧洲的旅行者带来了这种病毒，而不是来自亚洲的旅行者。
这两个团队都从3月中旬开始，分析了来自纽约确诊病例的新冠病毒基因组。研究发现，新冠病毒较早前很有可能在隐藏的状态下传播。
研究也指出，并非所有纽约的病毒样本都来源于欧洲。其中一些似乎来自美国西海岸，而另一些似乎与亚洲直接相关。这表明纽约的疫情有许多传播链。
参考资料：https://www.pnas.org/content/early/2020/04/07/2004999117/tab-figures-data