For winter sports, the NCAA has updated their guidelines to accommodate for the Omnicron variant for tier 1 individuals (those with the highest exposure). These guidelines follow the most recent updates made by the CDC and include recommendations/mandates for quarantine, isolation and vaccination status among other variables.
To paraphrase the NCAA Website, Tier 1 individuals, including student-athletes, officials coaches and other relevant staff member, are considered fully vaccinated if they are:
Within two months of having completed the primary series of the Johnson & Johnson vaccine (one dose).
Within five months of having completed the primary series of the mRNA Pfizer vaccine, or within six months of having completed the primary series of the mRNA Moderna vaccine (two doses for both).
An individual that has received a booster vaccine if they are beyond two months of the Johnson & Johnson vaccine or beyond five or six months of the mRNA Pfizer or Moderna vaccine, respectively.
If an individual has had a documented COVID-19 infection in the past 90 days, they are considered the equivalent of "fully vaccinated."
In terms of quarantining, it is recommended that anyone that receives a positive test quarantine for a total of 5 days with an additional five days recommended if they still exhibit symptoms. The individual can participate in athletic activities after the initial five days if they have a negative PCR/NAAT test or antigen test.
Close contacts that are considered fully vaccinated or have had a recent infection do not need to quarantine. However, the NCAA recommends wearing a mask around others socially for 10 days when not actively training/competing. Athletic activities are permitted without a mask. Individuals should test on day five, if possible, and test if symptomatic.