Wearing masks scientifically is an important measure to prevent novel coronavirus infection. In view of which situations or scenarios should wear masks, it is recommended to wear masks or not to wear masks, the epidemic prevention and control group of the joint prevention and control mechanism of the State Council issued the Guidelines for the Prevention of novel coronavirus Infection by the Public Wearing Masks (April 2023) on the 12th to provide authoritative guidance for the public to wear masks scientifically. Currently, China's epidemic prevention and control have achieved a smooth transition and achieved significant decisive victories. However, the global epidemic is still prevalent, and the virus strains are constantly mutating. There is still a risk of a rebound in the epidemic in China. In order to further improve epidemic prevention and control work and effectively prevent and control the spread of the epidemic, the Joint Prevention and Control Mechanism of the State Council has organized the development of a new version of mask wearing guidelines based on the first five editions. According to the guidelines, there are mainly three types of situations or scenarios where masks should be worn, including situations where there is a risk of epidemic transmission, situations or scenarios where there is a high risk of infection, and situations or scenarios where epidemic prevention is strictly prohibited from entering key institutions. Some members of the public are concerned about which situations or scenarios belong to the key institutions for strict epidemic prevention, and the guidelines clearly specify that foreign personnel should wear masks when entering places where vulnerable populations are concentrated, such as elderly care institutions and social welfare institutions. Medical, catering, cleaning, security and other public service personnel from key institutions such as elderly care institutions, social welfare institutions, childcare institutions, schools, and off campus training institutions should wear masks throughout their work to prevent the importation of the epidemic into relevant key institutions. The guidelines also specify that in situations or scenarios where the risk of infection is low, the risk of infection is effectively prevented, and the risk of infection is low, and wearing a mask may have a certain impact on work, life, and learning, masks may not be worn. For example, in outdoor places such as open-air squares and parks, or when people engage in sports. The relevant person in charge of the National Bureau of Disease Control and Prevention stated that the guidelines will be revised and improved based on changes in the epidemic situation and prevention and control needs. Each department in each region can formulate local and industry mask guidelines based on the actual situation of the local and industry, combined with the epidemic situation, and referring to this mask guide. The following is the full text of the guidelines: Guidelines for the Prevention of novel coronavirus Infection by the Public Wearing Masks (April 2023). Wearing masks scientifically is an important measure to prevent novel coronavirus infection. According to the requirements of the Overall Plan on the Implementation of "Class B and Class B Control" for novel coronavirus Infection and the Prevention and Control Plan for novel coronavirus Infection (Tenth Edition), the Guidelines are formulated to guide the public to wear masks scientifically and effectively protect public health. 1、 Circumstances or scenarios where masks should be worn 1. During the period when novel coronavirus antigen or nucleic acid test is positive. 2. During the period of fever, sore throat, cough, runny nose, muscle ache, fatigue and other suspected symptoms of novel coronavirus infection. 3. When a clustered epidemic occurs in the community or school where one lives, works or studies. 4. When seeking medical treatment, accompanying, accompanying, or visiting medical institutions. 5. When outsiders enter places where vulnerable populations are concentrated, such as elderly care institutions and social welfare institutions. During the working period of medical, catering, cleaning, security and other public service personnel in key institutions such as elderly care institutions, social welfare institutions, daycare institutions, schools, and off campus training institutions. 2、 Suggested wearing mouth