CDC director says number of U.S. Omicron cases "likely to rise"

• Whether Omicron is more transmissible than prior variants is not yet known, but there are some signs that it may not cause more severe disease than the other variants, Axios' Caitlin Owens writes.
• Speaking on ABC's "This Week," Walensky stressed that the more mutations a variant possesses, the more immunity an individual needs to prevent infection, adding that "we're really pushing to get more people vaccinated and more people boosted."

What they're saying: "We know it has many mutations ... and many of those mutations have been associated with more transmissible variants," Walensky told host Martha Raddatz.

• "What we don't yet know is how transmissible it will be, how well our vaccines will work, whether it will lead to more severe disease," she added.
• "We're really hopeful that our vaccines will work in a way that even if they don't prevent disease entirely, prevent infection entirely, that they can work to protect severe disease and keep people out of the hospital."