Researchers who have examined the genomes of two coronavirus infections in Washington State say the similarities between the cases suggest that the virus may have been spreading in the state for weeks.
研究人员对华盛顿州两次冠状病毒感染的基因组进行了分析，他们说，两例病例之间的相似之处表明，该病毒可能已经在该州传播了数周。
Washington had the United States’ first confirmed case of coronavirus, announced by the Centers for Disease Control and Prevention on Jan. 20. Based on an analysis of the virus’s genetic sequence, another case that surfaced in the state and was announced on Friday probably was descended from that first case.
疾病控制与预防中心于1月20日宣布，华盛顿确诊美国首例冠状病毒病例。基于对该病毒基因序列的分析，华盛顿州周五宣布确诊的另一例病例很可能来源于首例病例。
The two people live in the same county, but are not known to have had contact with one another, and the second case occurred well after the first would no longer be expected to be contagious. So the genetic findings suggest that the virus has been spreading through other people in the community for close to six weeks, according to one of the scientists who compared the sequences, Trevor Bedford, an associate professor at the Fred Hutchinson Cancer Research Center and the University of Washington.
这两人生活在同一个县，但彼此之间不曾有过接触，而第二个确诊病例发生在首例确诊患者预计不会有传染性之后。根据比较基因序列的一位科学家的说法，基因对比表明该病毒已经在社区中传播了近六周。这位科学家是弗雷德哈钦森癌症研究中心和华盛顿大学的副教授特雷弗·贝德福特。
Dr. Bedford said it was possible that the two cases could be unrelated, and had been introduced separately into the United States. But he said that was unlikely, however, because in both cases the virus contained a genetic variation that appears to be rare — it was found in only two of the 59 samples whose sequences have been shared from China.
贝德福特博士说，这两例病例也许没有关联，并以不同的方式传到美国。但是他说，这可能性很低，因为在这两例病例中，病毒都包含一种遗传变异，这种变异似乎是罕见的——在中国的59个样本中，只有两个样本中发现了这样的基因序列。
State and local health officials have been hamstrung in their ability to test widely for the coronavirus. Until very recently, the C.D.C. had insisted that only its test could be used, and only on patients who met specific criteria — those who had traveled to China within 14 days of developing symptoms or had contact with a known coronavirus case.
各州以及地方卫生官员在广泛测试冠状病毒方面的能力上受到了阻碍。 此前，疾病控制与预防中心一直坚持只能使用那里的试剂检测，并且只能用于符合特定标准的患者，即14天前到过中国旅行或接触过确诊患者后出现类似症状的人。
If the virus has been spreading undetected in Washington since mid-January, that could mean that anywhere from 150 to 1,500 people may have it, with about 300 to 500 people the most likely range, said Dr. Mike Famulare, a principal research scientist at the Institute for Disease Modeling in Bellevue, Wa., who performed the analysis. These people “have either been infected and recovered, or currently are infected now,” he said.
华盛顿州贝尔维尤疾病模型研究所的首席研究科学家Mike Famulare博士说，如果自1月中旬以来该病毒一直在华盛顿传播，却未被发现，则意味着可能有150至1,500人感染该病毒，最可能的范围是300至500人。他说，这些人“已经被感染并康复了，或者现在还是被感染的状态”。
Dr. Famulare’s estimate was based on a simulation using what scientists have learned about the incubation period and transmissibility of the virus. He called his figures a “best guess, with broad uncertainty.” Another method, based on the size of the local population, the number of tests performed and the proportion of those that were positive, produced similar estimates of how widely the virus may have spread in the community.
Famulare博士的估算基于模拟分析，该模拟用到了科学家对病毒的潜伏期和传染性的了解。他称这些数据是“最佳猜测，不确定性很大。” 另一种方法是根据当地人口的数量，进行的检测次数以及阳性检测的比例，用以说明该病毒在社区中的传播范围的，两种方法估算的结果相近。
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