One of the earliest, peer-reviewed studies looking into the Omicron variant of COVID-19 suggests that people previously infected with COVID, and those vaccinated, will have some, "stronger than basic" defence against this new strain of concern.
However, the test tube (or 'in-vitro', scientifically) samples of Omicron examined in this new research do show it "exceeds" all other variants in its potential capability to evade the protection gained from previous infection or vaccination.
For more details check out the link below:
Dr. Nandita Mohan
BDS, MDS( Pedodontics and Preventive Dentistry)