Installation of a gas heating system in new construction 2023/2024

If you deal intensively with how the effect is and also is supposed to be, then you understand that the immune system is kept on its toes … in some more, in others less … and when the RSV comes, the body has nothing left to oppose it.

Aha. Are you a medical professional? Otherwise, you probably don't have the basis to deal with something like this "intensively."
It's like an acquaintance who told me that at 0°C and 100% humidity, you shouldn't ventilate. Because the air outside is supposedly more humid than inside at 25°C and 80%.

Unfortunately, you often discuss with such "specialists"...

The discussion is pointless. There is a small group of people who base their opinions on sources that are provably false, presumably to feel "elitist," to not belong to the mainstream. That's how conspiracy things have always worked; there is (interesting) research and documentaries about that as well. We live in a world where practically all accumulated knowledge of humanity is only a mouse click away. Nevertheless, groups arise in this time claiming the Earth is flat, and mean it seriously. If someone wants to believe nonsense to be different, you unfortunately won’t change that with factual argumentation.

They do exist, but there are very few who believe in Reptilians, etc. However, there is also a group that only believes what is reported in the public broadcasting. Neither really cares about facts, but rather about their clients.

But anyone who considers "die Welt" an unreliable source is probably hard to "catch" again and would rather go through life with their eyes closed :).

Yep, Springer Press is highly reputable. You can tell from Mr. Döpfner, Mr. Reichelt, and all the other clowns who publish articles with personal opinions without properly labeling them. In the first half of the pandemic, I still found Tim Röhn somewhat worth reading when he still made an effort to look for facts amid all the madness. Then he switched to Welt and well… Unfortunately, not much of that remained.

What I find remarkable about Welt's online presence, by the way, is the linking of articles with the faces of the authors. I only know that from Fox News.