[Aromasin]

From my very basic understanding as an interested electronic engineer, while symptomatically pulmonary for the most part, COVID is a largely cardiovascular disease. Medical professionals please correct me if I'm wrong, but I've read that the most dangerous symptom, pneumonia, stems from fluid leaking into the lungs due to dilation of the blood vessels, along with causing joint pain, loss of taste and smell, and swollen limbs.

[shmooper]

COVID's most dangerous symptom is a condition called cytokine storm[1]. Cytokines are molecules used by the immune system as a means for communication, such as calling for help, cell destruction and more. COVID creates a "storm" of signals, driving the immune system crazy. As a part of the immune system reaction to those signals, inflammation can occur (as a way to isolate and fight a specific infected zone). During this attack, the immune system sends out cells from the blood and into the organs[2], making the blood vessels more permeable. I'm not certain but I believe that's the cardiovascular symptoms you're referring to.

1. The COVID-19 Cytokine Storm; What We Know So Far https://www.frontiersin.org/articles/10.3389/fimmu.2020.0144... 2. Leukocyte Migration into Inflamed Tissues https://www.sciencedirect.com/science/article/pii/S107476131...

[agumonkey]

From my even more basic understanding, the "vascular" part comes from covid affection for epithelial cell receptors, epithelial cells being about everywhere in your body (that's why it can propagate from nose to brain). I assumed the liver had similar tissue lining it's entry points.