https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7252012/
So far COVID-19 has killed about 0.04% of the world population.
> It's still endemic today, but most of us get infected as youths which provides some immunity later in life.
Right! That's why it's really a great analogy for SARS-2. I've been trying to get people to understand for awhile now that unlike say a really bad flu pandemic [flu has a bi-modal death distribution], SARS-2 kills the very elderly and the very sickly, but doesn't touch the very young. That means that once it's more-or-less fully spread through the population (as it has been doing the last 1.5 years or so), we're basically done with COVID-19 mortality forever.
Why? Because of exactly that reason: children will get exposed to SARS-2 young the same way they get exposed to the other circulating non-SARS hCoVs. And like any infection, once infected and recovered immunological memory persists for decades upon decades. Memory B/T cells hang around, ready and waiting to respond to the characteristic antigen when presented with them in the future.