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From://news.northeastern.edu/2020/04/26/covid-19-was-in-the-us-in-january-we-need-to-understand-how-we-missed-it/ 6park.com早在今年1月，在中国武汉市如雨后春笋般冒出来的“新型冠状病毒”，对美国许多人来说，至多是一个遥远的担忧。 6park.com
6park.com斯特恩伯格家族杰出大学教授亚历山德罗·韦斯皮尼亚尼（Alessandro Vespignani）说，但是导致COVID-19的冠状病毒SARS-CoV-2已经在美国主要城市中传播。而且，如果我们想确保社区安全向前发展，我们需要了解我们是如何漏掉了鼻子下面的病毒的。 6park.com
6park.comVespignani说：“我们不想在将来陷入这个陷阱。” 6park.com
6park.comVespignani和他的同事一直在使用一种模型来研究和预测该病毒的全球传播，这一发现表明该病毒已经在一月份在美国流行。该模型依赖于人类的流动性和相互作用方式，以及病毒的感染动态。 6park.com维斯皮尼亚尼说：“该模型使我们能够进入所谓的美国流行病的无形阶段。” “我们可以模拟开始本地传播链的感染者的到来。” 6park.com
6park.com该组织上个月发布的研究表明，封锁中国城市以及全球各国实施的出行限制为时已晚。冠状病毒已经出来。 6park.com
6park.com但是我们怎么想念它呢？为什么我们没有注意到人们生病？ 6park.com“在美国和欧洲，没有大规模的测试能力，并且指导原则是仅测试有旅行记录的人，” 6park.com维斯皮尼亚尼说。 “但是当您从已经在美国的某个人身上感染后，就没有旅行记录了。” 6park.com那是一月，是流感季节，冬季感冒和其他呼吸系统疾病的高峰期。如果没有近期来华的历史，就算是少数重症患者也不会引起太多关注。 6park.com
6park.com维斯皮尼亚尼说：“所以发生了一个半月的时间，这种流行病没有引起人们的注意。” “直到您遇到大量案件为止。然后，在那一点上，您开始看到冰山的一角。” 6park.com
6park.com作为从中国出发的国际旅行的枢纽城市，纽约，西雅图，旧金山，洛杉矶等，在美国看到的病例最早，但类似的感染链条已开始在世界范围内传播。到美国拒之门外或隔离来自中国的旅客时，冠状病毒已经在美国城市中传播，欧洲和其他地区也有新病例出现。 6park.com
6park.com考虑到过去几个月我们生活中发生的巨大变化，回首一月可能感觉就像是古老的历史。但是，了解这些疾病爆发的方式和时间可以帮助研究人员做出预测。 6park.com
6park.com“如果我从一月初开始流行，我可以预测一定的轨迹；如果我的流行从三月初开始，那么一切都将转移两个月，”维斯皮尼亚尼说。 “对于像这样的疾病，那是一个无限的时光。因此，您真的想尽可能地精打细算，直到一个星期的水平，现在就拥有正确的时间表，以告知我们未来几周或几个月内的情况。” 6park.com研究人员正在学习的知识还将帮助我们在感染数量下降并且我们开始采取物理疏导措施时做出明智的决定。 6park.comVespignani说，仅根据到国家或国际热点的旅行历史来测试该病毒还不够。如果我们没有进行更广泛的测试，并且能够追踪每个被感染者的联系方式，那么在我们不知情的情况下，第二波感染可能正在建立。 6park.comVespignani说：“我们不想陷入同样的境地。” “我们需要拥有所有这些，以便我们可以使原则上不可见的内容可见。” 6park.com[b]The coronavirus was in the US in January. We need to understand how we missed it.[/b] 6park.comBack in January, the “novel coronavirus” that had sprung up in the Chinese city of Wuhan was at most a distant worry for many people in the United States. 6park.com
6park.comBut SARS-CoV-2, the coronavirus that causes COVID-19, was already circulating in major U.S. cities, according to Alessandro Vespignani, Sternberg Family distinguished university professor, who directs Northeastern’s Network Science Institute. And if we want to keep our communities safe going forward, we need to understand how we missed a virus that was right under our noses. 6park.com
6park.com“We don’t want to fall into this trap in the future,” Vespignani says. 6park.com
6park.comThe discovery that the virus was already circulating in the U.S. in January comes from a model that Vespignani and his colleagues have been using to study and predict the global spread of the virus. The model relies on human mobility and patterns of interaction, as well as the infection dynamics of the virus. 6park.com“The model allows us to go into what we call the invisible stage of the epidemic in the United States,” Vespignani says. “We can simulate the arrival of infected people that were starting local transmission chains.” 6park.com
6park.comResearch that the group released last month shows that the cordoning off of cities within China, as well as travel restrictions implemented by countries around the globe, came too late. The coronavirus was already out. 6park.com
6park.comBut how did we miss it? Why didn’t we notice people getting sick? 6park.com“There was no large scale testing capacity in the U.S. and Europe, and the guidelines were to test only people with a travel history,” 6park.comVespignani says. “But when you get an infection from somebody who is already in the United States, you don’t have a travel history.” 6park.comIt was January—the height of flu season, winter colds, and other respiratory illnesses. Even the few people with severe cases would not have drawn much attention without a history of recent travel to China. 6park.com
6park.com“So what happened is that for a month and a half, the epidemic had gone unnoticed,” Vespignani says. “Until you have a critical mass of cases. Then, at that point, you start to see the tip of the iceberg.” 6park.com
6park.comCities that are hubs for international travel from China—New York, Seattle, San Francisco, Los Angeles—saw the earliest cases in the U.S. But similar chains of infection were beginning all over the world. By the time the U.S. was turning away or quarantining travelers from China, the coronavirus was already spreading through U.S. cities, and new cases were coming from Europe and other areas. 6park.com
6park.comGiven the amount of change our lives have undergone in the past few months, looking back to January may feel like ancient history. But understanding how and when these outbreaks started can help researchers make predictions down the line. 6park.com
6park.com“If I have an epidemic that starts in early January, I can project a certain trajectory; if I have an epidemic that starts in early March, everything is shifted by two months,” Vespignani says. “That’s an infinite time for a disease like this one. So you really want to be as sharp as possible, down to the level of a single week, to have the right timeline now to inform what we will see in the next weeks or months.” 6park.comAnd what the researchers are learning will also help us make smart decisions when the number of infections has dropped off and we begin to lift physical-distancing measures. 6park.comIt wasn’t enough to only test for the virus based on travel history to national or international hotspots, Vespignani says. If we don’t have more extensive testing, and the ability to trace the contacts of each infected person, a second wave of infection could be building without our knowledge. 6park.com
6park.com“We don’t want to find ourselves in the same situation,” Vespignani says. “We need to have all that so that we can make visible what, in principle, could be invisible.”
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