I don't think anything that Walensky said was incorrect. She just said that their studies thus far showed very low Covid infection rates and very low rates of virus detection in vaccinated people. In what way was what she said incorrect? Her starting the quote with "Our data from the CDC today suggests" indicates she is only commenting on what the data they have shows, and not making any promises or 100% guaranteed statements.

Then, someone under the same organization, a spokesperson whose job it is to speak about these things, further clarified that the statement was broad, but they never said it was incorrect or was not supported by the study cited by Walensky. This seems to be things working as intended, and anti-vaxx people then attempted to misconstrue this quote as a promise or guarantee.