美国疾控中心日前修改了疫情防控指导意见中关于密切接触者的定义，将时间较短但反复接触的情况也包括在内。新的定义明确，只要在24小时内与新冠病毒感染者接触时间累计达15分钟，就会被认定为密切接触者。

Federal health officials issued new guidance on Wednesday that greatly expands the pool of people considered at risk of contracting the novel coronavirus by changing the definition of who is a “close contact” of an infected individual.

美国联邦卫生官员本周三（10月21日）发布了新指导意见，该意见更改了新冠病毒感染者的“密切接触者”的定义，从而大大扩展了有感染新冠病毒风险的人群范围。

The change by the Centers for Disease Control and Prevention is likely to have its biggest impact in schools, workplaces and other group settings where people are in contact with others for long periods of time. It also underscores the importance of mask-wearing to prevent spread of the virus.

美国疾病控制与预防中心的这一改动可能对学校、办公场所和其他人与人长时间接触的聚集环境影响最大。该指导意见还强调了佩戴口罩以防止病毒传播的重要性。

The CDC had previously defined a “close contact” as someone who spent at least 15 consecutive minutes within six feet of a confirmed coronavirus case. The updated guidance, which health departments rely on to conduct contact tracing, now defines a close contact as someone who was within six feet of an infected individual for a total of 15 minutes or more over a 24-hour period, according to a CDC statement Wednesday.

美国疾控中心先前将“密切接触者”定义为在新冠肺炎确诊患者6英尺（1.8米）范围内持续停留至少15分钟的人。根据疾控中心周三发布的声明，新版指导意见现在将密切接触者定义为24小时内在感染者6英尺范围内停留时间总计达15分钟以上的人。该指导意见是美国卫生部门追踪密切接触者的依据。

The update comes as the United States is “unfortunately seeing a distressing trend, with cases increasing in nearly 75 percent of the country,” Jay Butler, the CDC’s deputy director for infectious diseases, said Wednesday at CDC headquarters in Atlanta, in the first news conference administration officials permitted in more than eight weeks. People may be tired of the advice, Butler said, but mask-wearing is more important than ever this fall and winter as Americans head indoors, where transmission risks are greater.

美国疾控中心负责传染病的副主任杰伊·巴特勒本周三在疾控中心位于亚特兰大的总部召开的新闻发布会上称，当前美国“不幸地呈现出一种令人不安的趋势，全国近75%的地区新冠确诊病例都在增加”。这是八周多以来政府官员许可召开的第一个新闻发布会。巴特勒说，人们也许听烦了这一建议，但是今年秋冬随着美国人待在室内时间变长，病毒传播风险变大，佩戴口罩比以往都更重要。

The guidance about transmission of the coronavirus, which causes covid-19, had been discussed by CDC scientists for several weeks, according to a CDC official who spoke on the condition of anonymity. Then came unsettling new evidence in a report published Wednesday. CDC and Vermont health officials discovered the virus was contracted by a 20-year-old prison employee who in an eight-hour shift had 22 interactions — for a total of over 17 minutes — with individuals who later tested positive for the virus.

疾控中心的一名官员匿名透露，关于新冠病毒传播的最新指导意见，疾控中心的科学家已经讨论了好几周。但是周三发布的一份报告提出了让人不安的新证据。疾控中心和佛蒙特州的卫生官员发现，一名20岁的监狱工作人员感染了新冠病毒，他在8个小时的值班过程中有过22次人员接触，总时长超过17分钟，和他接触过的人后来新冠病毒检测为阳性。

"This article adds to the scientific knowledge of the risk to contacts of those with covid-19 and highlights again the importance of wearing face masks to prevent transmission,” the CDC said.

疾控中心称：“这份报告增进了人们对于新冠病毒接触者风险的科学认识，再次凸显了佩戴口罩对于防止病毒传播的重要性。”

As many as half of all people who have the virus don’t show symptoms, “so it’s critical to wear a mask because you could be carrying the virus and not know it,” the CDC said. “While a mask provides some limited protection to the wearer, each additional person who wears a mask increases the individual protection for everyone. When more people wear masks, more people are protected.”

疾控中心表示，多达一半的新冠病毒感染者没有症状，“因此佩戴口罩很关键，因为你可能携带病毒而不自知。尽管口罩对佩戴者的保护作用有限，但是每多一个人佩戴口罩，就对每个人多一份保护。如果更多人佩戴口罩，就有更多人受到保护。”

Caitlin Rivers, an epidemiologist at the Johns Hopkins Center for Health Security, called the updated guidance an important change.

约翰斯·霍普金斯大学健康安全中心的流行病学家凯特琳·里弗斯称，指导意见的这一更新是重要改变。

"It’s easy to accumulate 15 minutes in small increments when you spend all day together — a few minutes at the water cooler, a few minutes in the elevator, and so on,” Rivers said. “I expect this will result in many more people being identified as close contacts.”

里弗斯说：“当你一整天都和其他人在一起时，碎片化的接触时间很容易就能累积到15分钟，比如饮水机边的几分钟，电梯里的几分钟，等等。我认为这将导致更多人被认定为密切接触者。”

She added: “This change underscores the importance of vigilant social distancing — even multiple brief interactions can pose a risk.”

她补充道：“这一改变强调了提高社交隔离警惕的重要性，因为即使是几次短暂的互动也会构成风险。”