北大医院李海潮谈新冠肺炎的几个问题 Thoughts on COVID-19
编者按
当前
新冠肺炎疫情呈全球蔓延趋势
北京大学校友会
特邀
北京大学第一医院副院长
呼吸和危重症医学科主任医师
北京大学援鄂医疗队成员
李海潮
针对近期出现的
关于COVID-19（新冠肺炎）的若干问题
进行详细解答
并翻译成英文
希望能够给海外友人提供经验借鉴
北大医院李海潮
谈新冠肺炎的几个问题
前情提要：
1.目前没有明确有效的抗病毒治疗药物；
2.长潜伏期不必担心；
3.完全符合出院标准，核酸复检阳性不代表复发；
4.出院患者目前宜在家继续隔离14天；
5.空气传播需要特定条件（封闭空间、长时间滞留），没有必要因此升级防护和消毒措施；
6.公共场所戴外科口罩，手卫生更为重要。
是否存在抗病毒治疗药物？
A:
可以说，目前没有明确有效的抗病毒治疗药物。至于正在进行临床研究的药物有没有用，等结果。因此，对于COVID患者，尤其是轻症患者，用各种抗病毒药物没有意义，反而可能有不少副作用。轻症患者绝大多数可以自愈，只需要对症处理即可。
关于长潜伏期的说法是否可信？
A:
目前公认的潜伏期是1-14天，最常见是3-7天，现在所有隔离规定的时间都是按照这个来设定的。是不是有报道说潜伏期长达20余天。我想：第一，这些都是极少见的个案，而且新闻工作者不是流行病学家，不一定能把可能接触的情况搞的非常清楚（当然流行病学调查也可能不一定搞清楚，何况还存在故意隐瞒信息的情况），所以，是否真的有这么长，存疑；第二，即便有这么长的，也是极小概率事件，其影响也是非常局限的，最坏的可能是造成一个点的传播。没有看到在长潜伏期者到处传播的情况。所以，长潜伏期可能有，需要注意，但从整体上看，其影响基本可以忽略不计，至少不必因此惊慌。
出院后核酸复检阳性意味着什么？
A:
如果确诊为新冠肺炎患者，经过治疗后症状显著改善、胸部CT显示阴影明显吸收，或遗留纤维索条影（以后还会再吸收一些）呈现为恢复期改变，两次核酸检测阴性，就可以出院。现在还增加了抗体阳性。这些病人在出院后再次核酸检测阳性不说明疾病又复发了！！！
有些患者恢复期相对长，是因为肺功能没有完全恢复，还会觉得易疲劳，活动后气短，只要情况在持续好转中就没有问题！！！这是核酸检测阳性，提示患者还可能带病毒，有可能排出病毒。这个情况的流行病学意义有待研究。
对于这种情况，目前的有些措施具有防范作用，比如出院后继续隔离14天。再增加一段时间，其转成阴性的可能性将随着时间的延长进一步增加。会不会出现类似于“伤寒玛丽”（传染病史上的著名个案，大家可以网上查）的持续排毒者，估计可能性极低。这些带“毒”者的传染病学意义有待进一步观察，因为核酸阳性并不意味着一定就会传染其他人。
我们目前是非常敏感的定性测量，不是定量测量，而病毒传播效果和病毒数量关系非常大。如果只是阳性，而数量很少，基本就没有意义。所以复检阳性的意义待确定后，出院是否需要隔离14天，需要等待研究结果（这是后话）。
因此，复查阳性的恢复期患者，第一，不要担心疾病复发，耐心康复；第二，执行出院后14天隔离。
如何科学有效防护？
A:
因为最重要的传播途径是飞沫传播和接触传播，所以在公共场所（有确诊感染患者的地方），佩戴医用外科口罩，勤洗手，养成不用手摸东西，尤其不去摸颜面五官的习惯非常重要。
带N95口罩没有必要，把它留给进感染病房的医务人员吧。
现在所说的空气传播，包括有宣传尿、便里有病毒，可能造成气溶胶传播，这是极小概率事件。传播发生的可能性是在病毒含量高的密闭空间滞留时间过长。因此，只要注意开窗通风，人与人之间保持距离，基本就不会发生。
关于公共场所消毒问题的建议。
A:
感觉目前消毒有些过了，像地面喷洒消毒剂意义不大。就算地面有病毒，存活时间也就几个小时。在它活着的这几个小时，第一，飞不起来（随飞沫掉到了地上），第二，即便是飞起来了，也达不到空气传播所需要的数量，构不成威胁。因此，没有必要在通风良好的区域使劲喷洒消毒剂。因为飞沫可能粘在衣物上的病毒数量也会很多，也会很快死掉，把衣服挂起来，晾一夜应该就没有问题了，没有必要不停的洗。
至于其他表面消毒，只在有确定患者停留或触摸过的区域需要重视，适当消毒即可——最最关键的还是注意个人的手卫生。我不提倡用纸巾触摸门把手或电梯按钮，太浪费纸巾了，关键是没有必要。凡是触摸过可疑或不确定表面的情况，回到家里或办公区域，把手洗干净最重要，就够啦，有手消毒剂也可以。
Thoughts on and Prevention Measures
against COVID-19
Author
Li Haichao
Division of Respiratory and Critical Care Medicine, Peking University First Hospital, A member of the national emergency medical rescue team from Peking University to Wuhan，Hubei.
Key points
1. There are no specific antiviral drugs.
2. There is no need to worry about the long incubation period.
3. For patients who are fully in line with the discharge criteria, positive results of the nucleic acid retest do not necessarily mean recurrence.
4. The discharged patients should quarantine themselves at home for 14 days.
5. Airborne transmission requires specific conditions (confined space, prolonged contact), so there is no need to upgrade protection and disinfection measures.
6. More important measures are to wear surgical masks in public spaces, and pay attention to hand hygiene.
Detailed explanations
1. Regarding possible antiviral drugs: It can be said that there are no definitely effective antiviral drugs at present. As for the effectiveness of the drugs under clinical trials, we must wait for the results. Therefore, for COVID-19 patients, especially for the mild cases, the use of a variety of antiviral drugs is not effective, and may lead to several side effects. Most mild patients can heal by themselves and only need symptomatic treatment.
2. About the long incubation period: Currently, the recognized incubation period is between 1 to 14 days, most commonly between 3 to 7 days. Now all the quarantine requirements are set in accordance with this knowledge. How about the report saying that the incubation period is as long as more than 20 days? In my opinion: First, these are extremely rare cases. Journalists are not epidemiologists, so they might not be able to get a clear picture of possible contacts (of course, epidemiological investigations may not be clear, either, especially when deliberate concealment of information occurs). Therefore, the actual incubation period of these cases is doubtful. Second, even if the incubation period lasts that long, it remains a small probability event. Its impact is also very limited, the worst of which may be point-spreaders.There is no case of super-spreaders with a long incubation period. To conclude, the incubation period may be long, which requires attention. In general, however, the impact is basically negligible. There is no need to panic.
3. About the positive results of the nucleic acid retest after discharge: For a COVID-19 patient, discharge should be approved once symptoms are significantly improved after treatment and the chest CT shows obvious shadow absorption, or the remaining fibrous cord shadow (some will be absorbed later) shows convalescent changes, and two nucleic acid tests are negative. Now another criterion has been added that the antibody test should be positive. The fact that a discharged patient is tested positive for nucleic acid again does not mean recurrence!!! The recovery period of some patients is relatively long, because their lung function has not fully recovered. They may easily feel tired, and will be short of breath after exercises. As long as their condition continues to improve, it will be fine!!! Positive results of the nucleic acid retest suggest that a discharged patient may still carry the virus, but it is also possible for the virus to be expelled. The epidemiological significance of this situation needs further research. For this situation, some current measures demonstrate preventive effects, such as a prolonged quarantine period of 14 days after discharge. With the passage of time, the possibility of the test result turning negative will be further increased. Will there be a continuous spreader like "Typhoid Mary" (a famous case in the history of infectious diseases)?The estimation is highly unlikely. The infectious significance of these "poisonous" people remains to be seen, because a case with a positive nucleic acid test result is not necessarily infectious. At present, we employ very sensitive qualitative measurement, not quantitative measurement, but the effect of virus transmission is closely related to the number of the virus. If the test is positive, while the virus number is very small, it is basically non-significant. Therefore, the significance of positive retests remains to be determined. More researches are needed in the future to decide whether discharged patients are required a 14-day quarantine. In summary, for convalescent patients who are retested positive: first, do not worry about recurrence. Be patient and wait for recovery. Second, follow the 14-day quarantine protocol after discharge.
4. About protection: Since the commonest routes of transmission are droplet transmission and contact transmission, it is very important in public places (and places where patients are diagnosed) to wear medical surgical masks, wash hands frequently, and avoid touching things, especially the face. There is no need to wear an N95 mask, which is needed by the medical staff in the infection ward. Airborne transmission is a small probability event, which is also the case for the news that the presence of virus in urine and stool may cause aerosol transmission. Transmission is possible on the condition of a prolonged stay in a confined space with high virus content. Therefore, as long as we pay attention to ventilation and keep the distance between people, transmission will basically not happen.
5. About disinfection in public space: My feeling is that disinfection measures have gone too far now. Spraying disinfectant on the ground is of little significance. Even if there is virus on the ground, it will only survive for a few hours. During the time, firstly, it cannot fly (as it falls to the ground with droplets). Secondly, even if it flies, it cannot accumulate the number needed for airborne transmission, hence no threat. So there is no need to spray massive disinfectant in well-ventilated areas. Because droplets may stick to clothes, there could be a large number of the virus on the clothes. But the virus will die soon, so there should be no problem as long as the clothes are hung overnight. It is unnecessary to keep washing clothes. As for other surface disinfection, attention should only be paid to areas where patients definitely stay or touch. Proper disinfection is enough.
6. About hand hygiene facilities：The most, most important thing is to pay attention to hand hygiene. I do not advocate touching doorknobs or elevator buttons with paper towels, which is a huge waste, as well as an unnecessary measure. If you have touched a suspicious or uncertain surface, it is of vital importance to wash your hands after you go back to your home or the office area. Hand-washing is enough. Hand disinfectant is also recommended.
Translated by Huang Rong
School of Health Humanities, Peking University
日前，“微医互联网总医院”针对新冠肺炎推出全球抗疫平台，联合中国医师协会和中国医促会，为海外侨胞免费提供24小时线上咨询、心理援助和防疫知识科普服务，供有需要的海外校友参考使用。具体信息如下：
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亦可点击文末“阅读原文”链接，直接进入服务页面。
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功能介绍
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我们再次提醒广大海外校友，在线咨询是特殊时期给海外侨胞提供的一个便利咨询渠道，并不能替代实际医疗机构的诊断治疗。如出现疑似症状或身体不适，请第一时间联系当地医疗机构寻求帮助。
亲爱的海外校友们
从未名湖畔到天南海北
请相信
未名博雅，日月盈仄
北大，从未离开
我们也始终与你们同在
请相信
爱与希望，无远弗届
我们终将战胜疫情
虽隔千万里
心意总相连
这里有你想念的一草一木
也有时刻关心牵挂你的人们
我们在你我共同的家
愿你平安健康
等你欢聚团圆
作者：李海潮 北京大学第一医院副院长、北京大学援鄂医疗队成员、北京大学第一医院呼吸和危重症医学科主任医师
翻译：黄蓉 北京大学医学人文学院博士后
感谢：郭莉萍 北京大学医学人文学院教授
责编：陈韩梅