ChicagoGranny wrote: ↑Sat Sep 05, 2020 11:14 am
There are also ACE2 receptors on the surface of alveolar cells in the lungs.
Sure, but the mechanism is believed to be that the virus attaches to the ACE2s in the nose and starts replicating. Then after the volume of virus increases by a gazillion-fold, it travels down the respiratory tract and into the lungs. We know that in 60-80% of exposures, the virus doesn't get a foothold. Sometimes the initial exposure isn't enough and the virus just dies back. Sometimes the person's T-cells kill it. Some people get as far as antibodies and they produce enough of them and fast enough that they can beat the infection back. But, anyway, we are pretty sure that the virus can't attack the lungs directly, and it needs that beachhead in the nose to replicate and produce enough virus copies to seriously threaten the lungs.
It's believed that the reason that it is so difficult for children to get covid is that the density of ACE2 receptors in the nose goes up sharply by age (see the graph in this paper:
https://www.researchgate.net/publicatio ... and_Adults )
As an analogy, think about the D-Day invasion. Certainly from the beginning of the war the Allies could bomb the Germans, and sneak small numbers of saboteurs in, but we weren't going to win the war without an invasion which landed large numbers of troops on the continent. From Normandy, the Allied troops then advanced across France and invaded Germany. But before any of that could happen, the troops had to make it onto the beaches, and past the German defenders. That's not so different from what happens when an individual's nose gets invaded by Covid -- the virus has to battle through multiple layers of immune defense in order to get the opportunity to invade the lungs.
Now the reason that D-Day succeeded ultimately is that the entire coastline of France was too much to defend, and the Allies kept the landing site secret so that they only had to overwhelm a relatively small force of German defenders. As opposed to two nostrils which is a very small target to defend. And as all of us cpap users are completely aware, you don't need both mouth AND nose to breathe, you can totally get by with one or the other. The problem with wearing a facemask is that it covers both mouth and nose, and it can't cover them particularly completely or you can't breathe.
I'm just wondering if it would work to only protect the nose -- and completely protect It with something like these --
https://www.cpap.com/productpage/fisher ... racle-mask while leaving the mouth clear to breathe.
