I. Coronavirus is very small, can wearing a mask keep it out? Yes. Because the role of the mask is to block the “carrier” of virus transmission, rather than directly blocking the virus. There are two common modes of transmission of respiratory viruses: close contact and long-distance aerosol transmission. The so-called “aerosols” that we can generally come into contact with are droplets from patients. Properly worn masks can effectively block the droplets, which will also block the virus from entering the human body directly. It should be reminded that it is not necessary to wear KN95 or N95 masks, general surgical masks can also block most of the viruses stuck on the droplets from entering the respiratory tract. Second, the coronavirus is so powerful, soap and water hand washing can work? Yes. Washing hands regularly is one of the clear measures to prevent viral infections such as rhinovirus and coronavirus. By applying soap adequately and rubbing the action, it can effectively remove dirt and microorganisms from the skin surface, while rinsing off the soap with running water can also minimize the irritation to the skin. For this reason, the National Center for Disease Control and Prevention, WHO and the U.S. CDC and other authorities recommend adequate hand washing with soap and water (running water). What can I do if I don’t have water to wash my hands with when I travel? You can use alcohol-based disinfectant products to clean your hands. Human coronavirus is acid- and alkali-intolerant and sensitive to organic solvents and disinfectants. 75% alcohol can inactivate the virus, so an alcohol-based disinfectant at a certain concentration can be an alternative to soap and running water.