I verified the CDC guidance.
Seems they are back to the soft carrot policy language approach, however they have used some danger words that can be used to rapidly expand under new conditions:
Protection provided by the current vaccine against symptomatic infection and transmission is less than that against severe disease and diminishes over time, especially against the currently circulating variants. For this reason, it is important to stay up to date, especially as new vaccines become available.
"Up to date" will perhaps be very integral in the design of a new app waiting to be rolled out?
Concerning isolation, the drafters have used one "need" word, as opposed to 'should' word:
There is much difference between the words you 'should' and you 'need' to.