The correct answer to this open question is the following.
In many different pages can be searched to find information. But I think that the federal government page takes you to some interesting links regarding public schools and prevention measures. That is where I focused my research.
So I found general recommendations that seem understandable. For instance, the detection of the temperature at the main gates of the schools. If students are sick, they better stay at home. You have to avoid contact with people sick. When coughing or when sneezing, the main recommendation is to cover your mouth with both hands or a tissue. Wash your hands constantly if you were outside. Do not touch your face. Stay at home if you can. And instead of using masks, eat well, have nutritious foods, improve your immune system, and do not have fear due to misinformation.
If there are people infected, they have to go to hospitals to get a diagnosis and receive the best treatment. The use of homeopathic medicine is a great and valid alternative that is working very well in other countries.