Dr. Stuart Campbell Ray, an infectious disease expert at Johns Hopkins University explainin elusive herd immunity, or "universal immunizition"

Omicron is more likely[?!] than delta to reinfect individuals who previously had COVID-19 and to cause "breakthrough infections" in vaccinated people while also attacking the unvaccinated.
[...]
"People have wondered whether the virus will evolve to mildness. But there's no particular reason for it to do so," he said.

except the 100-year transformation of 1918 H1N1 AKA Spanish Flu into "seasonal strains"

Experts say the virus won't become endemic like the flu as long as global vaccination rates are so low. ...

Moderna hopes to market combined COVID and flu booster in 2023