COVID isn’t special in terms of viruses or disease. What’s making it different is that it’s effectively a new virus that NOBODY was immune to back in late 2019/early 2020. So at first, it was going to spread without any real hindrance through the population, as there was no immunity to it.
Eventually enough people will end up mostly immune one way or another (either via vaccination or catching COVID) that it won’t spread very fast or hardly at all anymore. Or the disease itself will mutate into something less lethal or less transmissible. It’ll happen at some point- that’s what happens in all pandemics. The Black Death eventually ended, and so have the various influenza pandemics over the past several centuries.
That was the pie-in-the-sky hope with the vaccines- that enough people would get vaccinated fast enough that we could sort of jump the line and not have a LOT of people catching it and a smaller, but significant number dying as a result. That didn’t come to pass, for reasons we’re all aware of.
What will end up happening is that once we hit a certain point of immunity in the population, the spread will be extremely low, and basically it’ll be treated much the same as say… the flu. People will get periodic vaccines against the variants that are in play, and the unvaccinated will just get sick and deal with it. Nobody will have to wear masks or social distance or any of that- there won’t be a need.
This will happen in rich and poor countries, with the main distinction being how the immunity is acquired- richer countries will have higher vaccination rates, and poorer ones will have higher rates of people catching it and surviving.
Ultimately it will be endemic- it already is. But what we’re seeing right now is the Delta variant ripping through the unvaccinated. This is unfortunate and largely preventable, but at some point fairly soon, enough of the “right” people will become immune (right in the sense of people who are very mobile and social and spread the disease effectively), and the spread will slow dramatically. Hopefully having had Delta will confer immunity in whole or part to other variants, and the spread will be very slow.