Hopefully... the history of diseases before vaccines (polio, measles, smallpox, black plague, etc) doesn't exactly fill me with a lot of hope for it just becoming less deadly naturally, even if there are examples (Spanish flu) where they have.

What are the histories of the other coronaviruses? And would those histories be more relevant than histories of non coronaviruses?

Another coronavirus probably caused a worldwide pandemic starting in 1889. It killed a lot of people, but the survivors gained natural immunity which gave them significant protection against symptomatic reinfections. The same virus HCoV-OC43 is still endemic today. This seems relevant to the current pandemic.

https://sfamjournals.onlinelibrary.wiley.com/doi/10.1111/175...

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7252012/

'The evidence 1889-1890 outbreak was caused by a coronavirus has been referred to as "weak" and "conjectural" in an analysis of the literature'

Seems this theory has only gained traction in the last 2 years.

Looking into it further, case fatality rate of during the 1889-90 outbreak seemed to be 0.1-0.28, much lower than Covid-19 has been.

Our data on the 1889-90 pandemic is pretty thin. We don't have any reliable records on deaths in poorer countries so the error bars are quite wide.

A lower infection fatality rate in that previous pandemic is not at all surprising. Back in 1889 elderly people made up a much lower fraction of the population. And there was a lower rate of co-morbid conditions such as obesity, diabetes, and hypertension.

Sure, there have been a lot of Flu pandemics with lower case fatality rates as well. Prior to this pandemic, they had actually narrowed down the flu subtype:

"the reanalysis of seroarcheological data suggested Influenza A subtype H3 (possibly the H3N8 subtype) as a more likely cause for the 1889–1890 pandemic"

There was no thoughts that it was Coronavirus related before this pandemic.

edit: Interestingly though, the 1889-90 pandemic was thought to have originated in Bukhara, part of the Russian empire at the time, which has been historically a cattle raising area. H3N8 is Equine influenza virus, where as HCoV-OC43 was a Bovine coronavirus.

I understand this is a reoccurring theme throughout history that lead to most of the endemic coronaviruses today. Omicron is truly fantastic; for example look at Ontario’s case count vs ICU count. Omicron has completely decoupled those graphs.

It's not really clear whether that is because it is less severe or if it is because there are lots more breakthrough infections.

(but a larger number of mild breakthrough infections is not itself terrible news either as the mildness indicates a population becoming more resilient against the virus)

It’s perfectly clear, across the world vaccinated or unvaccinated hospitalizations and severities are reduced. South Africa on one extreme and New South Wales on the other. Ontario a textbook example of a first world society’s expectation vis a vis vaccination, age curves, and severity.

Common cold has a variety of coronaviruses

Do you have sources for that? Because isn’t that exactly what has not happened with all the existing variants?