“It seems that the basic principle is that anything touching on the welfare of the public, or the removal of harm from it, is all considered danger to life, because anything bound up with the public’s welfare has, indirectly, an element of danger to life. The livelihood of an individual, for example, does not involve danger to life; but if the public lacks livelihood, then even if this does not relate to bread, it is unavoidable that among the many there will be someone who needs better food, such that for him this could be a matter of danger to life. And likewise any war that brings prosperity, and by means of that makes it possible to care better for the sick and the weak—something not possible when economic conditions are poor. And likewise a war whose purpose is to increase the king’s renown—it may be assumed that because of this enemies will fear to attack, and more will wish to enter into alliance with him, which also brings about a better economic situation, and through that public health increases. And similarly, regarding the removal of public harm in the case of a burning ember: although in itself this is not dangerous, it is still possible that the injured person will be unable to go out to work, and it is also possible that he is alone and will be unable to tell someone to come help him, and thus this small matter can lead to danger to life. And so too with all sorts of similar scenarios: if we consider them regarding an individual, this is remote, and there is no need to be concerned; nevertheless, on a public scale it ultimately does happen, and with regard to danger to life this too is taken into account” (Rabbi S. Yisraeli, Amud HaYemini, pp. 214–215)

Can there really be any doubt about the above???

There can. In the case of the ember, it is itself a complete danger; only the chance of damage is small. Here, the harmful party itself is not a complete danger.

Could the Rabbi explain his words—what does “not a complete danger” mean?

This is an assessment of reality. An ember certainly burns (it is definitely harmful); the question is only whether there is someone for it to harm. The chance of the harm being realized is small. In contrast, when one person meets another and neither of them is known to be ill, there is no definite harmful agent here, only a possible one. The problem is not only whether the meeting will cause infection, but whether the person being met is even contagious at all. Here there is no harmful agent to begin with. The doubt is whether there is any harmful agent, and whether that harmful agent will in fact infect. That is a double disadvantage, unlike the ember.

Binyomine said

As for your question, there’s a simple solution: you can walk over to the commander-in-chief in the war on corona, the great rabbi, mighty and towering, our master Rabbi Y. Litzman, may he live long, and he will do whatever is needed to stop the plague with the help of the energetic Gur Hasidim. Even if you have to walk an hour in the pouring rain, it’s worth it in place of danger to life for the public 🙂

However, a question remains about your own precious life: after all, you can’t know about every single case of some Haredi person somewhere in their crowded neighborhoods full of human flocks, and therefore all your reporting is like putting a finger in the dike, and you’ve achieved nothing in stopping the plague.

Therefore the recommended advice is: “Flee, my beloved”—keep your feet from dwelling in their neighborhoods, and even staying there for the time it takes to eat a half-loaf should be avoided; you should refrain from entering their settlements altogether. And as the wise man said: “My son, do not go on the way with them; keep your foot from their path.” Keep your way far from them, and then you will dwell in safety, quiet and at ease.

Signed, in honor of enlightenment and its seekers,
Dr. R. M. From-Man, secular Haredi

Even in a triple doubt case, such as clearing away rubble from on top of a person when there is doubt whether he is there or not, and also doubt whether he is alive or dead, and also doubt whether he is a Jew or a gentile, one desecrates the Sabbath—yet the collapse is not definitely harmful, and maybe there is no harmful agent here at all?

??
A collapse is not definitely harmful? When there is already a person under it?

??
Coronavirus is not definitely harmful? When there is already a person “under” it?
I really don’t understand the distinction…

It really is not harmful. Even someone who is affected by coronavirus has almost no chance that anything will happen to him. So with coronavirus the doubt is about the harmful agent itself, whereas with a collapse or an ember the doubt is only whether it will cause harm.