Why can't you have such a fever?

Because the body is invaded by too many bacteria. There are bacteria in the human body more or less. When catching a cold, the human body's resistance drops, and bacteria take advantage of it. They will fight against white blood cells, the health guard of the human body. Because the human body's resistance drops, white blood cells sacrifice more, and the heat emitted by white blood cells and bacteria will gather when fighting, which will lead to the increase of human body temperature. At this time, people have a fever. As for what you have done, it shows that your resistance can adapt to the temperature of 16 degrees! The virus cannot attack your white blood cells yet.