据中国政府网和国家卫生健康委联合提供的“疫情风险等级查询”小程序信息显示，截至4月19日18时，北京市朝阳区为高风险地区，成为全国唯一高风险地区。
As of 6 pm Sunday, Chaoyang district in Beijing had a red alert indicating the highest risk classification on the health-tracking app. Other Chinese cities — including Wuhan, the hardest hit city in China during the COVID-19 outbreak; the northeastern cities of Harbin and Suifenhe; and the southern city of Guangzhou — are all marked as low- or middle-risk areas.
截至4月19日18时，北京市朝阳区在该健康追踪小程序中被列为红色高风险地区，而国内新冠肺炎疫情最严重的武汉市、东北地区的哈尔滨以及绥芬河，还有华南地区的广州市均被标注为低风险或中风险地区。
4月20日下午，在北京市新型冠状病毒肺炎疫情防控工作新闻发布会上，北京市疾控中心副主任庞星火介绍了朝阳区被列为高风险地区的相关情况。
按照国家《关于依法科学精准做好新冠肺炎疫情防控工作的通知》要求，各地需要根据当地新冠肺炎疫情情况进行风险分级和分类防控。
【知识点】
依据国务院应对新型冠状病毒感染肺炎疫情联防联控机制《关于科学防治精准施策分区分级做好新冠肺炎疫情防控工作的指导意见》中的风险划定标准：
Cities, counties and districts with no newly confirmed cases in the last 14 days are categorized as low-risk regions, those with fewer than 50 cases or those with over 50 but without a concentrated outbreak are classified as medium-risk regions, and those with over 50 cases as well as a concentrated outbreak are classified as high-risk regions.
即以县市区为单位，无确诊病例或连续14天无新增确诊病例为低风险地区;14天内有新增确诊病例，累计确诊病例不超过50例，或累计确诊病例超过50例，14天内未发生聚集性疫情为中风险地区;累计病例超过50例，14天内有聚集性疫情发生为高风险地区。
照此标准，4月14日，北京朝阳区确诊的一例境外输入性病例(imported case)造成其家庭3人的关联性病例，成为一起聚集性疫情(concentrated outbreak)。因此，朝阳区疫情风险级别定为高风险地区。
Up to 62 of his close contacts were put under medical isolation and observation.
该病例的62名密切接触者已进行医学隔离和观察。
针对这起疫情，北京已迅速隔离治疗病例，严密开展流行病学调查(epidemiological investigation)和隔离密切接触者(isolate close contacts)，并对病例同楼相关居民和环境进行了核酸检测，结果均呈阴性。对病例曾经活动场所和区域均进行了终末消毒(terminal disinfection)。
【相关词汇】
传染病检疫及监测
quarantining and monitoring of infectious diseases
病毒携带者
virus carrier
传染途径
route of transmission
输入病例
imported case
流行病学调查
epidemiological investigation
集中观察
concentrated observation
外防输入、内防反弹
to prevent the coronavirus from re-entering the country to cause a new epidemic
境外输入关联病例
cases resulting from virus carriers traveling from abroad; patients infected by virus carriers traveling from abroad
参考来源：Sixth Tone
