【Cochrane简语概要】诸如洗手或戴口罩之类的物理措施会阻断或减缓呼吸道病毒的传播吗？

什么是呼吸道病毒？

呼吸道病毒是感染呼吸道，即鼻腔、咽喉和肺，内部细胞的病毒。这些感染会导致严重健康问题并影响正常呼吸。它们会引起流感（流行性感冒），严重急性呼吸综合征（非典，severe acute respiratory syndrome，SARS）和新型冠状病毒肺炎（COVID-19）。

呼吸道病毒如何传播？

感染呼吸道病毒的人咳嗽或打喷嚏时会将病毒微粒传播到空气中。当其他人通过空气或落有病毒微粒的物体表面与这些病毒微粒接触，就会被感染。呼吸道病毒可以在社区、人群和国家以及在世界各地迅速传播。在国家中传播被称为瘟疫（epidemics），在全球范围传播被称为大流行（pandemics）。

我们该如何阻断呼吸道病毒的传播？

阻断呼吸道病毒在人与人之间传播的物理措施包括：

· 经常洗手；

· 不要触摸眼睛、鼻子或嘴巴；

· 在打喷嚏或咳嗽的时候用肘部挡住嘴；

· 用消毒剂擦拭物体表面；

· 戴口罩、护目镜、手套和穿着防护服；

· 避免与其他人接触（患者隔离或检疫隔离）；

· 与他人保持一定距离；

· 检查从其他国家入境的人是否有感染迹象（筛查）。

我们为什么进行这项Cochrane综述

我们想知道物理措施是否阻断或减缓了呼吸道病毒的传播。

我们做了什么？

我们检索了通过物理措施阻断人们感染呼吸道病毒的相关研究。

我们感兴趣的是这些研究中有多少人感染了呼吸道病毒，以及这些物理措施是否造成任何不利影响。

检索日期：本综述为2007年首次发表的综述进行的更新。我们纳入了截至2020年4月1日发表的研究。

我们的发现

我们检索筛选出了67项相关研究。这些研究发生在世界各地的低、中、高收入国家，研究纳入人群来源自非流感时期、2009年全球H1N1流感大流行时期以及至2016年的流行性流感季时期的医院、学校、家庭、办公室、托儿所和社区。没有在COVID-19大流行期间进行的研究。我们检索筛选到6项正在进行的，尚未发表的研究，其中三项评估了戴口罩对COVID-19的影响。

1项研究着眼于检疫隔离的影响。没有关于护目镜、制服和手套、或者对进入国家的人进行检查的物理措施的研究。

我们评估了以下物理措施的影响：

· 医用或外科口罩；

· N95/P2呼吸器（经常被医务工作者而非普通民众使用的有过滤吸入的空气功能的紧密口罩）；

· 手卫生（洗手和使用手部消毒剂）。

本综述的结果是什么？

医用或外科口罩

七项研究是在社区中进行的，两项研究在医务工作者中进行。与不戴口罩相比，戴口罩对流感样疾病的人数没有或有很少影响（9项研究，涉及3507名受试者），对通过实验室检查确诊为流感的人数可能没有影响（6项研究，涉及3005名受试者）。很少有关于不良反应的报告，但有研究提到不适。

N95/P2呼吸器

四项研究是在医务工作者中进行的，一项小型研究在社区中进行。与戴医用或外科口罩相比，戴N95/P2呼吸器对确诊流感的人数影响不大或没有影响（5项研究，涉及8407名受试者），对流感样疾病发生人数（5项研究，涉及8407名受试者）或呼吸道疾病发生人数（3项研究，涉及7799名受试者）的影响也几乎没有差别。不良反应没有得到很好的报告。有研究提到不适。

手卫生

与未执行手卫生相比，进行手卫生可能减少呼吸道或流感样疾病人数和确诊流感人数（16项研究，涉及61372名受试者）。很少有研究衡量不良反应，但有提到使用手消毒剂的人的皮肤刺激情况。

这些研究结果的可靠性？

与呼吸系统疾病相关的主观结果的证据质量较低。但对于与口罩和N95/P2呼吸器相关的更精确定义的实验室确诊呼吸道病毒感染，证据为中等质量。当有更多证据出现时结果可能会改变。相对较少的人遵循了有关戴口罩或手卫生的指导，这可能会影响研究结果。

关键信息

我们不能确定是否戴着口罩或N95/P2呼吸器有助于减缓呼吸道病毒的传播。

手卫生可能有助于减缓呼吸道病毒的传播。

（图片来源于pixabay.com）

结论: 

试验的高偏倚风险、结局测量的多样性、以及研究期间对干预措施较低的依从性妨碍了明确结论的生成与研究结果到当前的COVID-19大流行的推广。

口罩的效果尚不确定。低中等质量证据意味着我们对干预措施效果估计的信心有限，并且真实可以造成的影响可能与通过观察估计的有所不同。随机试验的合并结果并未显示季节性流感期间使用医用/外科口罩可明显减少呼吸道病毒感染。作为减少呼吸道病毒感染的常规护理措施，医务工作者使用医用/外科口罩与N95/P2口罩比较，并没有明显的效果差异。手卫生可能会适度减轻呼吸道疾病的发生。与物理干预有关的危害未得到充分研究。

有必要进行大规模、设计良好的RCT，以研究这些各类干预措施在多种环境和人群中的有效性，特别是在最易发生ARIs的人群中的有效性。

译者：余泽宇，北京中医药大学循证医学中心；审校：李迅，北京中医药大学循证医学中心；编辑排版：郑偌祥、张晓雯，北京中医药大学循证医学中心

相关文章链接

【Cochrane Plain Language Summary】Do physical measures such as hand-washing or wearing masks stop or slow down the spread of respiratory viruses?

What are respiratory viruses?

Respiratory viruses are viruses that infect the cells in your airways: nose, throat, and lungs. These infections can cause serious problems and affect normal breathing. They can cause flu (influenza), severe acute respiratory syndrome (SARS), and COVID-19.

How do respiratory viruses spread?

People infected with a respiratory virus spread virus particles into the air when they cough or sneeze. Other people become infected if they come into contact with these virus particles in the air or on surfaces on which they have landed. Respiratory viruses can spread quickly through a community, through populations and countries (causing epidemics), and around the world (causing pandemics).

How can we stop the spread of respiratory viruses?

Physical measures to try to stop respiratory viruses spreading between people include:

· washing hands often;

· not touching your eyes, nose, or mouth;

· sneezing or coughing into your elbow;

· wiping surfaces with disinfectant;

· wearing masks, eye protection, gloves, and protective gowns;

· avoiding contact with other people (isolation or quarantine);

· keeping a certain distance away from other people (distancing); 

· examining people entering a country for signs of infection (screening).

Why we did this Cochrane Review

We wanted to find out whether physical measures stop or slow the spread of respiratory viruses.

What did we do?

We searched for studies that looked at physical measures to stop people catching a respiratory virus infection.

We were interested in how many people in the studies caught a respiratory virus infection, and whether the physical measures had any unwanted effects.

Search date: This is an update of a review first published in 2007. We included evidence published up to 1 April 2020.

What we found

We identified 67 relevant studies. They took place in low-, middle-, and high-income countries worldwide: in hospitals, schools, homes, offices, childcare centres, and communities during non-epidemic influenza periods, the global H1N1 influenza pandemic in 2009, and epidemic influenza seasons up to 2016. No studies were conducted during the COVID-19 pandemic. We identified six ongoing, unpublished studies; three of them evaluate masks in COVID-19.

One study looked at quarantine, and none eye protection, gowns and gloves, or screening people when they entered a country.

We assessed the effects of:

· medical or surgical masks;

· N95/P2 respirators (close-fitting masks that filter the air breathed in, more commonly used by healthcare workers than the general public); 

· hand hygiene (hand-washing and using hand sanitiser).

What are the results of the review?

Medical or surgical masks

Seven studies took place in the community, and two studies in healthcare workers. Compared with wearing no mask, wearing a mask may make little to no difference in how many people caught a flu-like illness (9 studies; 3507 people); and probably makes no difference in how many people have flu confirmed by a laboratory test (6 studies; 3005 people). Unwanted effects were rarely reported, but included discomfort.

N95/P2 respirators

Four studies were in healthcare workers, and one small study was in the community. Compared with wearing medical or surgical masks, wearing N95/P2 respirators probably makes little to no difference in how many people have confirmed flu (5 studies; 8407 people); and may make little to no difference in how many people catch a flu-like illness (5 studies; 8407 people) or respiratory illness (3 studies; 7799 people). Unwanted effects were not well reported; discomfort was mentioned.

Hand hygiene

Following a hand hygiene programme may reduce the number of people who catch a respiratory or flu-like illness, or have confirmed flu, compared with people not following such a programme (16 studies; 61,372 people). Few studies measured unwanted effects; skin irritation in people using hand sanitiser was mentioned.

How reliable are these results?

Our confidence in these results is generally low for the subjective outcomes related to respiratory illness, but moderate for the more precisely defined laboratory-confirmed respiratory virus infection, related to  masks and N95/P2 respirators. The results might change when further evidence becomes available. Relatively low numbers of people followed the guidance about wearing masks or about hand hygiene, which may have affected the results of the studies.

Key messages

We are uncertain whether wearing masks or N95/P2 respirators helps to slow the spread of respiratory viruses.

Hand hygiene programmes may help to slow the spread of respiratory viruses.

Authors' conclusions: 

The high risk of bias in the trials, variation in outcome measurement, and relatively low compliance with the interventions during the studies hamper drawing firm conclusions and generalising the findings to the current COVID-19 pandemic.

There is uncertainty about the effects of face masks. The low-moderate certainty of the evidence means our confidence in the effect estimate is limited, and that the true effect may be different from the observed estimate of the effect. The pooled results of randomised trials did not show a clear reduction in respiratory viral infection with the use of medical/surgical masks during seasonal influenza. There were no clear differences between the use of medical/surgical masks compared with N95/P2 respirators in healthcare workers when used in routine care to reduce respiratory viral infection. Hand hygiene is likely to modestly reduce the burden of respiratory illness. Harms associated with physical interventions were under-investigated.

There is a need for large, well-designed RCTs addressing the effectiveness of many of these interventions in multiple settings and populations, especially in those most at risk of ARIs. 

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