美國醫學會臨床醫學期刊於2020年3月4日報導指出，醫療用口罩和N95口罩都可用來預防呼吸道感染，兩者不同在於過濾顆粒的種類及大小，但建議有呼吸道感染症狀的人，例如：咳嗽、打噴嚏、發燒，才須配戴口罩；此外，醫護人員、照護病患者或與患者密切接觸的人，也應配戴口罩，目前沒有證據顯示，健康的人戴口罩能夠有效預防疾病。建議在配戴口罩之前，先正確洗淨雙手， 洗手洗得正確是達到最佳防疫效果的重要關鍵之一。

(財團法人國家衛生研究院 蔡慧如博士摘要整理)

Medical masks are a tool that can be used to prevent the spread of respiratory infection.

Medical masks are a type of personal protective equipment used to prevent the spread of respiratory infections. These masks cover the mouth and nose of the wearer and, if worn properly, may be effective at helping prevent transmission of respiratory viruses and bacteria.

There are 2 main types of masks used to prevent respiratory infection: surgical masks, sometimes referred to as face masks, and respirators. These masks differ by the type and size of infectious particles they are able to filter. Face masks are used more commonly for respiratory viruses that spread via droplets, which travel short distances and are transmitted by cough or sneeze. Face masks often fit loosely, and prevent the wearer from spreading large sprays and droplets, as well as preventing hand-to-face contact. N95 respirators block 95% of airborne particles. They are tight fitting and prevent inhalation of smaller infectious particles that can spread through the air over long distances after an infected person coughs or sneezes. Diseases that require use of an N95 respirator include tuberculosis, chickenpox, and measles. N95 respirators cannot be used by individuals with facial hair or by children because it is difficult to achieve a proper fit. In those cases, a special respirator called a powered air-purifying respirator may be used instead.

Face masks should be used only by individuals who have symptoms of respiratory infection such as coughing, sneezing, or, in some cases, fever. Face masks should also be worn by health care workers, by individuals who are taking care of or are in close contact with people who have respiratory infections, or otherwise as directed by a doctor. Face masks should not be worn by healthy individuals to protect themselves from acquiring respiratory infection because there is no evidence to suggest that face masks worn by healthy individuals are effective in preventing people from becoming ill. Face masks should be reserved for those who need them because masks can be in short supply during periods of widespread respiratory infection. Because N95 respirators require special fit testing, they are not recommended for use by the general public.

If wearing a face mask is indicated, it is important to wash your hands with soap and water for at least 20 seconds prior to putting on the face mask. An alcohol-based sanitizer that contains at least 60% alcohol can also be used if soap and water are unavailable.

After cleaning your hands, place the face mask over your nose and mouth. Make sure there are no gaps between the face mask and your face, and ensure a tight seal. Try to avoid touching the face mask when wearing it. If you do touch the face mask, wash your hands or use hand sanitizer again. When you are done using the face mask, remove it without touching the front of the face mask, and discard it into a closed bin. Wash your hands again after discarding the face mask.

Author：Angel N. Desai, Preeti Mehrotra
原文連結：https://jamanetwork.com/journals/jama/fullarticle/2762694