Coronavirus - how much infected?

Since maybe early April when the number of new cases in the U.S. began rapidly rising, I have wondered: Doesn't it matter to what extent a person is infected by the coronavirus? Mildly infected likely means no or mild symptoms. Severely infected likely means severe symptoms, maybe hospitalization or worse. Of course, the strength of the person's immune system can constrain the severity of symptoms.

I finally saw an article that has some answers to my question.

40% of people with coronavirus have no symptoms. Might they be the key to ending the pandemic?

The article taught me another word, inoculum, the amount of virus someone is exposed to. It also says that wearing a mask might constrain the degree of infection.

A different article includes the following.

“When we looked in the setting of Covid disease, we found that people who had prior vaccinations with a variety of vaccines — for pneumococcus, influenza, hepatitis and others — appeared to have a lower risk of getting Covid disease,” Dr. Andrew Badley, an infectious disease specialist at Mayo Clinic told CNN’s Anderson Cooper on Monday night.

It’s what immunologists call immune training: how your immune system creates an effective response to fight off infections, Badley says.

This article has more about the immune response.

This article has more about potential immunity to the coronavirus.