[wim]

That is incorrect. While other viruses also can be round, "corona" typically used for common cold and SARS/MERS viruses (also common cold viruses, which just hide better before the immune system detects and fights them, causing more damage by bigger numbers).
The "flu" is short for influenza. There are 4 types of flu viruses, none of which are named "corona".
Short overview of influenza viruses:
https://www.cdc.gov/flu/about/viruses/types.htm

Corona viruses are cold viruses (there are other virus types that are also called "cold" virus).
Short overview of corona viruses:
https://coronavirusexplained.ukri.org/en...e/cad0003/

Overview of common cold viruses:
https://www.webmd.com/cold-and-flu/cold-...old_causes

So, while corona viruses have their name because of their round shape, not all round viruses are corona viruses. Red Robins (roodborstje) are named after their red (orange) breast. But other birds with red in their plumage are not all red robins...

Nope, you're (partly) wrong. I read articles on corona-viruses which cause flu many years ago already, even before SARS-type infections started.

A simple, quick search showed this, f.e.: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4703274/

IOW, Corona-viruses (HCoV) have been known to cause flu-like symptoms, and were known already in the 1960s . I also know that there have been at least several flu-vaccines over the years to provide protection against these as well, depending on what the expectations were for a particular year with regard to flu-strains to be going around.

The main difference is that these were, and are, HCoVs (H for Human), rather than CoVs, which may originate from a non-human host, and which are the strains currently causing havoc worldwide.