It's a
headline. The headline isn't written by the CDC, it's not even written by the journalist, it's just a one-line summary written by the newspaper editor meant to get people to look at the article. If you read the article you can see that it's a %, not 100%, but they're not going to turn every newspaper headline into a math problem.
If you see a headline that states "Poor black defendants don't get fair trials" or "California's students aren't passing their reading exams", would you assume that meant absolutely 100% or would you just assume it's a generalization and then read the article to find out the answer?
The CDC clarified her statement immediately. As in within hours:
Can Vaccinated People Spread the Virus? We Don’t Know, Scientists Say. (Published 2021)
“Dr. Walensky spoke broadly during this interview,” an agency spokesman told The Times. “It’s possible that some people who are fully vaccinated could get Covid-19. The evidence isn’t clear whether they can spread the virus to others. We are continuing to evaluate the evidence.”
There were literally thousands of statements released by the CDC and literally thousands of interviews done, and you're trying to cherry-pick a single line out of a single interview that was immediately clarified and create an entire narrative from it.
The CDC was linking their info constantly, directing you to their site over and over again, where the exact information was available with the exact %'s at all moments. They were never hiding shyt, they were begging you to look at the full info. Every doctor was getting the same information too, you could ask any of them. But you flip over one loose generalization in an interview. The standard you're asking isn't one that would be possible or demanded from any other issue at any other time.