>So, why aren’t they all dead?
maybe it's because
The CDC recently updated survival rates (i.e., IF infected) for COVID-19:
0-19 yrs old: 99.997%
20-49 yrs old: 99.98%
50-69 yrs old: 99.5%
70+ yrs old: 94.6%
These statistics do not factor in comorbidities. Assuming 10-15% of people infected are already in poor health or have some sort of immune deficiency, even the 70+ age group has a high rate of survival.
Put another way, healthy people, regardless of age, have more than 99% chance of surviving COVID-19 if they ever get it. In fact, using traditional statistical rounding, only 70+ is less than 100% survival rate and that is 95% of infected people. It is safe to say, many people who are otherwise healthy may get a little sick and get through it without even realizing it.