Book excerpt: In recent days, people around the world are living in panic and panic when the severe coronary pneumonia virus is raging in Wuhan City - in central China. Currently, on January 31, 2020, the World Health Organization (WHO) has declared the corona virus epidemic to be a global emergency medical condition. This makes the people 's spirit even more confused. Where I live and work, in Vietnam, family members rushed to buy medical masks. Many businesses have taken advantage of this worrying psychology to profit, selling medical masks and hand sanitizer for 10 to 12 times the normal price. Of course the government and authorities have stepped in to stabilize the situation, but people's psychology is still insecure. As a doctor, I believe that the panic comes from people not being fully equipped with corona virus, how it spreads, as well as medical masks that help protect against viral infections or not, how to use medical masks properly and effectively. So I wrote this booklet, with the desire to give people a true - simple - useful understanding of corona virus and how to prevent it from spreading in the community. Specifically include: 1. Basic knowledge of corona virus, as well as how it is transmitted in the community. What to do if you have signs of someone infected with corona virus? 2. What types of medical masks are used and work to prevent corona virus infection in the community? And how to use medical masks properly and effectively. 3. Some important notes to improve the body's resistance, help fight corona virus effectively. Sincerely thank you!