There’s good reason to think that Omicron spreads more rapidly than previous versions of the SARS-CoV-2 virus. That would be both because of inherent transmissibility and because of greater likelihood of breakthrough infections for those that have had Covid-19 before as well as those fully vaccinated (and even boosted) against it, though boosters do appear to provide greater protection than mere vaccination.
With Omicron appearing headed towards dominance in parts of Europe, outcompeting Delta, and with cases rising rapidly we are facing a conundrum.