A very good start to the description of the immune response. One of the most important aspects of everything is that our immune system has to make two distinct determinations about any object it encounters: is this object _foreign_ (thus not made by our own body), and is this object _malicious_? The interesting aspect is how long we too as a community to realize the second requirement exists and is extremely important. The first suggestion that we might have a system to independently determine whether an object is pathogenic was only made in 1989, which is very late for such a fundamental discovery indeed. Whether it's a virus or bacteria, our immune system has to primarily ascertain that it's pathogenic before it can do anything about it.

Importantly, when the immune system goes haywire like it does in Covid, it's because of some fuckery with this system that is at the root cause more often than not.