This video is the very first of the ones I shot to answer the questions that were posed to me.

Here is what the question’s author wrote:
“Susceptibility. What exactly is this? What triggers it? What can cause a previously harmless factor, such as a bacterium, to become harmful?”

He hit the nail right on the head.
That is, regarding the most important point – which is also known to medical science, and yet we do not apply it in everyday life.

Familiarize yourself with it!