“During May–November 2021, case and hospitalization rates were highest among persons who were unvaccinated without a previous diagnosis. Before Delta became the predominant variant in June, case rates were higher among persons who survived a previous infection than persons who were vaccinated alone. By early October, persons who survived a previous infection had lower case rates than persons who were vaccinated alone.”
https://www.cdc.gov/mmwr/volumes/71/wr/mm7104e1.htm
Unvaccinated with an omicron infection is not necessarily the same thing, and isn't likely to have as strong an immune response.