Herd immunity is natures way,up until now, with few exceptions.
So, put 2 n 2 together.
We can't stop it. Check.
It's highly contagious check
We may have a vaccine in 18 months, check,maybe
So, whats that leave us with?
As for the spanish flu, we simply didn't have enough doctors, nurses hospitals, no gloves, maybe rags for masks if worn, little aspirin, no communication for best patient handling, a far less healthy population, poor cares etc etc etc.
What can be learned is, both viruses were highly infectious, we could stop neither
We still don't have enough doctors, hospitals, and PPE to handle the herd immunity strategy... nor will we ever. Far less healthy population? We have better healthcare, which has prolonged the life of unhealthy individuals more than ever.. but make no mistake, our population is not healthier today than it was then.
We can't stop Covid-19 as of yet, but we can manage it and buy more time to figure out how to stop it. You'd think with all the technology in this world focused on one virus we would be able to at least figure out how to treat it in a reasonable amount of time.