We had what I think was a cold virus go through our household in October. Daughter had a sore throat and coughing for a couple days then got better. Wife had sore throat for one day then got better with no other symptoms. I was OK during that time then it hit me and progressively got worse and worse, had sore throat, coughing, sneezing, fever, etc. Began to get better after 5 days but the congestion and cough stuck for a good two weeks after that and I would feel fatigued and weak with any sort of exertion. I wonder if it could have been Covid-19 but at the time the symptoms kept leaning towards a cold (there was a good symptom checker quiz on the CDC website that gave guidance between Covid, cold, flu, or allergies) and I never felt I needed to risk going out to see a doc or get a test.
Anyhow, for years, we have seem similar behavior when a virus goes through our family. It happened a lot when my daughter was in pre-school -- after going 5-10 years between getting cold/flu, I was suddenly getting it 3-4 times a year. My daughter almost always had it pretty easy. Usually my wife or I would get it a lot worse, but never both of us the same way, or never both at the same time. There was a wide range of severity across the three of us. In that sense, Covid-19 is no different than other viruses (of course, some cold viruses are also corona viruses). I think where Covid differs are the oddball symptoms like loss of taste and smell, and rashes, which are atypical for cold and flu.
I have a friend who is a firefighter, and Covid-19 spread through the fire house back in May. He only had sore throat and headache, but other guys had a wide range of symptoms. Some had none at all. Figure that was about a dozen guys and there was a big range of symptoms. I remember reading an article where Fauci was explaining that past exposure to certain viruses could affect how a body responds to Covid. All depends on how the immune system has developed in a person and how responsive it can be. I am sure this would all be fascinating to learn about if it wasn't hurting our economy and suppressing many people's jobs and lifestyles...