You could comment on the paucity of effective RNA virus vaccines - polio and measles are probably the only effective ones.
Just checking from a list on google, so I could be very wrong.
Rabies, Influenza A + B, yellow fever, Ebola (that one's recent), hep A, mumps, etc etc.
You do tend to find that you only get a vaccine when it's an illness that effects westerners, or is particularly nasty, and doesn't have effective treatments etc.
There's coronavirus vaccines for cattle (money is important, more than poor peoples lives). Anything that can actually earn money for research companies (as research is not cheap, and fails a lot), will have people trying for a vaccine. Anything that mainly effects poor africans/indians etc, isn't, there's no profit margin.
Until Sars, there was no need for a coronavirus vaccine in humans. Sars went away quickly, so what was the point. MERS is still around, and as I've said, that's why Oxford is so much further ahead, because they've used a similar basis for covid19 as they had for Mers, meaning they could safely skip a few steps.