FAQs on asymptomatic infections of COVID-19 关于新冠肺炎无症状感染者的问题解答

Q: How to define asymptomatic infected persons of COVID-19?

什么是新型冠状病毒无症状感染者？

Asymptomatic infected persons of COVID-19 (hereinafter referred to as asymptomatic infected persons) refer to those who do not show any relevant clinical symptoms, such as fever, cough, sore throat and other self-perceived or clinically recognizable symptoms, but whose respiratory tract specimens test positive for COVID-19. Asymptomatic infected persons can be divided into two categories:

新冠病毒无症状感染者（以下简称无症状感染者）是指无相关临床症状，如发热、咳嗽、咽痛等可自我感知或可临床识别的症状与体征，但呼吸道等标本新冠病毒病原学检测阳性者。无症状感染者可分为两种情形：

One is that infected persons who test positive in the nucleic acid test do not show any self-perceived or clinically recognizable symptoms after the 14-day observation of the incubation period and the infection has been asymptomatic. 

一是感染者核酸检测阳性，经过14天潜伏期的观察，均无任何可自我感知或可临床识别的症状与体征，始终为无症状感染状态；

The other is that infected persons who test positive in the nucleic acid test do not show any self-perceived or clinically recognizable symptoms when sampling, but later develop some clinical symptoms. That is "asymptomatic infection" during the incubation period.

二是感染者核酸检测阳性，采样时无任何可自我感知或可临床识别的症状与体征，但随后出现某种临床表现，即处于潜伏期的“无症状感染”状态。

Q: Can asymptomatic infected persons spread the disease?

无症状感染者有无传染性？ 

According to the monitoring data released by the State and some provinces, some asymptomatic infected persons have caused second-generation transmission among their close contacts, and they have set off a small number of clusters of infections according to epidemiological investigations. Studies with small sample sizes have shown that the viral loads in the respiratory samples of asymptomatic cases do not demonstrate distinct difference from those of confirmed cases.

根据国家和部分省份开展的密切接触者监测数据，无症状感染者的密切接触者存在二代病例续发，流行病学调查中发现个别由无症状感染者导致的聚集性疫情，有小样本量的研究显示无症状感染者呼吸道样本中的病毒载量与确诊病例没有太大差异。

According to the current monitoring data and research, asymptomatic infected persons are contagious, but the length of the contagion period, the strength and pathway of transmission need to be further studied.

综合目前的监测和研究，无症状感染者存在传染性，但其传染期长短、传染性强弱、传播方式等尚需开展进一步科学研究。

Some experts believe that the risk of spreading the virus caused by asymptomatic infected persons is relatively lower than that by confirmed patients because asymptomatic infected persons show no clinical symptoms such as cough and sneezing though the pathogenic nucleic acid can be found in their respiratory tract specimens. 

部分专家认为鉴于无症状感染者的呼吸道标本能检出病原核酸，但由于无咳嗽、打喷嚏等临床症状，病原排出体外引起传播的机会较确诊病例相对少一些。

Q: What are the requirements for the prevention and control of asymptomatic COVID-19 infections in China? 

我国关于新型冠状病毒无症状感染者的防控要求是什么？

Protocol for Prevention and Control of COVID-19 (Edition 3) released by the National Health Commission on January 28 included asymptomatic infected persons into the prevention and control management scope. In the subsequent revision process, the report and management requirements of asymptomatic infected persons have been clearly specified by the National Health Commission. Medical and health institutions at all levels and of all kinds shall report asymptomatic infected persons they have identified directly through online platforms within two hours.

国家卫生健康委在1月28日发布《新冠病毒感染的肺炎防控方案》（第三版）中就将新型冠状病毒无症状感染者纳入防控管理，在其后的修订过程中均对无症状感染者的报告、管理等提出了明确具体的要求。各级各类医疗卫生机构发现无症状感染者，应于2小时内进行网络直报。

Upon receiving the report of asymptomatic infected persons, CDCs at the county (district) level shall complete the case investigation within 24 hours and have the people in close contact with asymptomatic infected persons registered in time. The case investigation form or investigation report shall be timely reported through the report and management information system for infectious diseases.

县（区）级疾控机构接到无症状感染者报告后，24小时内完成个案调查，并及时进行密切接触者登记，将个案调查表或调查报告及时通过传染病报告管理信息系统进行上报。

Asymptomatic infected persons shall be collectively quarantined for 14 days. In principle, the quarantine can be lifted for those who have been quarantined for 14 days and tested negative for nucleic acid tests in two consecutive samples (the minimum interval of sampling time shall be at least 24 hours).

无症状感染者应集中隔离14天，原则上集中隔离满14天且两次连续标本核酸检测阴性者（采样时间至少间隔24小时）可解除隔离；

If the result of the nucleic acid test is still positive, the quarantine shall be continued.

如果核酸检测仍为阳性者，则继续隔离医学观察。

Asymptomatic infected persons shall be defined as confirmed COVID-19 cases in time for standard treatment if they show clinical symptoms during the quarantine.

隔离医学观察期间如出现临床表现，应及时转归为确诊病例，进行规范治疗。

People in close contact with asymptomatic infected persons shall also be collectively quarantined for medical observation for 14 days.

无症状感染者密切接触者也要进行14天的集中隔离医学观察。

Q: How to identify asymptomatic infected persons? 

无症状感染者通过什么途径发现？

Asymptomatic infected persons are mainly identified proactively through the following ways:

1. Proactive nucleic acid tests for people under medical observation who were traced to have had close contact with confirmed COVID-19 patients;

2. Proactive nucleic acid tests for people who were traced to be related to COVID-19 case clusters according to relevant investigations; 

3. Proactive nucleic acid tests for people who were traced to have been exposed to sources of COVID-19 infection; 

4. Proactive nucleic acid tests for people who had a history of travel or residence in the COVID-19 outbreak areas home or abroad.

目前我们主要通过以下途径主动发现无症状感染者：

一是对新型冠状病毒肺炎病例的密切接触者开展医学观察期间的主动检测；

二是在聚集性疫情调查中开展的主动检测；

三是在新型冠状病毒肺炎病例的传染源追踪过程中对暴露人群主动检测；

四是对部分有境内外新型冠状病毒肺炎病例持续传播地区的旅行史和居住史人员开展主动检测。

Q: How to evaluate the risks posed by asymptomatic infected persons, and how to prevent and control the spread of COVID-19 caused by these persons?

如何做好无症状感染者的风险评估及其防控？

Asymptomatic infected persons pose risks of the spread of COVID-19.

1. The spread is latent. As asymptomatic infected persons do not exhibit any obvious symptoms of COVID-19, it is hard to identify them among crowds, and correspondingly, it is hard to prevent the spread of COVID-19 caused by them. 

2. The symptoms are subjective. Some asymptomatic infected persons only exhibit mild symptoms of COVID-19 or even exhibit non-typical symptoms. They may consider themselves not being infected with COVID-19, and will not seek medical treatment proactively, and therefore will be hard to be detected in the daily diagnosis.

3. The identification has limitations. Nucleic acid tests and serology tests are not able to identify all asymptomatic infected persons because there exists a window period from getting infected with COVID-19 to generating detectable antibodies. Those having been identified so far were mainly detected when they underwent tests because they were traced to have had close contact with confirmed patients, be related to case clusters, be exposed to sources of infection, or had a history of travel or residence in high-risk regions. Some asymptomatic infected persons remain hard to identify。

无症状感染者存在着传播风险。

一是传播的隐匿性。由于无症状感染者无任何明显的症状与体征，其在人群中难以被发现，其导致的传播也难以预防。

二是症状的主观性。症状轻微或不典型者可能认为自己没有感染新冠病毒，不主动去医疗机构就诊，在日常的诊疗工作中难以被发现。

三是发现的局限性。由于存在检测窗口期，采用核酸检测和血清学检测方法难以发现全部无症状感染者，现有的无症状感染者主要是通过病例的密切接触者主动筛查、感染来源调查、聚集性疫情调查和对高风险地区人员的主动检测发现的，尚有部分无症状感染者难以被发现。

It is therefore important to step up efforts to identify asymptomatic infected persons. Existing screening processes shall be intensified, and the scale of screening shall be expanded to include persons in close contact with confirmed cases and asymptomatic cases, key regions and key groups. Those being identified as asymptomatic infected persons shall be quarantined and undergo medical observation in strict accordance with the “early detection, early reporting, early isolation, and early treatment” principles. Those who have had close contact with asymptomatic infected persons shall also be quarantined for medical observation.

为此，要突出做好无症状感染者监测，有针对性加大筛查力度，将检测范围扩大至已发现病例和无症状感染者的密切接触者、重点地区和重点人群等。一旦发现无症状感染者，要立即按“四早”要求，严格集中隔离和医学观察，对密切接触者也要实施隔离医学观察。

As some asymptomatic infected persons will never exhibit symptoms of COVID-19, it is impractical to make the identification and quarantine of asymptomatic infected persons the main measure. Our emphasis will continue to be laid on the identification and quarantine of confirmed patients while enhancing management on those who have had close contact with the confirmed patients.

由于部分无症状感染者始终无症状，实际防控工作中无法将发现和隔离无症状感染者作为主导措施。因此我们仍将继续着重于及时发现隔离确诊患者，并做好密切接触者管理。

China’s experience has manifested that, if patients are being identified and quarantined in time, and measures such as reducing contact with people are implemented, the spread of COVID-19 can basically be curbed.

我国经验表明，做好确诊病例的及时发现和隔离，并适度采取减少人际接触等措施，可以基本阻断疫情传播。

Q: What measures will be taken to strengthen the prevention and control of asymptomatic COVID-19 infections?

下一步如何做好无症状感染者防控管理？

First, improve the prevention and treatment plans. A certain proportion of samples will be taken from areas severely affected by COVID-19 to investigate asymptomatic infected persons and conduct epidemiological analysis and research so as to improve prevention and control measures and enhance the prevention, control and treatment plans. Scientific measures will be taken to cope with risks of contagion caused by asymptomatic infected persons and contain further possible spread of the virus.

一是完善防治方案。抓紧在疫情重点地区抽取一定比例样本，开展无症状感染者调查和流行病学分析研究，完善防控措施，修订完善防控方案和诊疗方案，科学应对无症状感染者带来的感染风险，遏制可能形成新的疫情传播。

Second, intensify screening and detection. The screening will be stepped up in a targeted manner and the detection range will be expanded to people in close contact with confirmed patients and asymptomatic infected persons, key areas and key groups. The monitoring of key cities, key groups and key venues should be intensified while taking into consideration the resumption of work, production and schools, to identify hidden risks as much as possible. Efforts should be made to prevent cross-border transmission, and all travelers entering the country should take nucleic acid tests. Once an asymptomatic infected person is identified, an epidemiological investigation should be carried out to trace the source and related information should be released in an open and transparent way.

二是加大筛查监测。有针对性加大筛查力度，将检测范围扩大至已发现病例和无症状感染者的密切接触者、重点地区和重点人群等。结合复工复产复学实际，加强对重点城市、重点人群、重点场所的监测，最大程度发现隐患。做好疫情跨境输入输出防范，对所有入境人员进行核酸检测。发现无症状感染者后，及时开展流行病学调查，查清来源，公开透明发布信息。

Third, strengthen management and treatment. Once an asymptomatic infected person is identified, the patient should be put under collective quarantine and medical management, as required by the principles of “early detection, early reporting, early isolation, and early treatment”. People who have had close contact with the infected person should be put under quarantine for medical observation as well. If any of them shows symptoms of COVID-19, he/she should be transferred to a designated hospital for treatment.

三是强化管理救治。一旦发现无症状感染者，要立即按“四早”要求，严格集中隔离和医学管理，对密切接触者也要实施隔离医学观察。隔离期间出现症状，立即转运至定点医疗机构进行救治。

Fourth, intensify mass prevention and control. The public and the government should work together. More efforts should be made to promote knowledge on epidemic prevention among the public and guide the public in scientific prevention and protection. Training should be held extensively to improve the epidemic prevention and control capability of CDC personnel, medical staff and community staff at the grass-roots level. From April 1, information on asymptomatic infections including the report of new cases, their development into symptomatic cases, and the management of the cases will be released in the COVID-19 updates in response to public concerns.

四是加强群防群控。坚持群专结合，加大防疫知识科普宣传力度，指导公众科学防护，广泛开展培训，提高基层疾控人员、医务人员和社区工作人员等的防控能力和水平。从4月1日起在疫情通报中公布无症状感染者报告、转归和管理情况，及时回应社会关切。

Q: What personal protective measures should be taken?

如何做好个人防护？

The public should strengthen the self-protection and health awareness, and improve environmental sanitation as well as personal hygiene habits, adopting a healthy lifestyle including washing hands regularly, wearing face masks, sanitizing hands, keeping at least one meter away from others, keep windows open for ventilation, regular disinfection, packing food in separate servings, avoiding crowded places while sick, and wearing face masks properly. 

公众要加强自我保护和健康文明意识，强化环境卫生及个人卫生防护，养成勤洗手、戴口罩、讲究手卫生、一米线、开窗通风、清洁消毒、分餐制、生病时减少去人员聚集场所和科学戴口罩等健康生活行为方式。

The public should engage in the patriotic health campaign. For protecting the health of ourselves and others, health knowledge shall be disseminated to every family and individual. The public shall develop good hygiene habits, adopt a civilized, healthy and green lifestyle, and improve mental as well as physical health.

要广泛开展爱国卫生运动，本着既保护自己，也要保护他人健康的理念，将健康知识传播到每个家庭和个人，形成良好卫生习惯和文明健康、绿色环保的生活方式，提升心理健康水平和健康素养水平。

Don’t panic if you test positive in nucleic acid tests and cooperate with medical institutions in health monitoring, quarantine and medical observation. If you show any symptoms like fever or cough, please make timely reports and accept standard treatment in a medical institution.

如个人核酸检测阳性后不必恐慌，要主动配合医疗卫生机构做好健康监测和隔离医学观察，出现发热、咳嗽等症状后及时报告，接受医疗机构规范诊治。

Foreign Affairs Office of Shenzhen Municipal People’s Government

Shenzhen Municipal Health Commission

April 2, 2020

深圳市人民政府外事办公室

深圳市卫生健康委员会

2020年4月2日