Title is inaccurate clickbait. You make it sound like getting vaccinated makes you infectious. And they are not "admitting" something, they are just reporting the latest data which has been collected on delta cases.

As to efficacy, the data out of Israel is the most concerning, with signs that vaccination effectiveness may be waning over time (as anti-bodies drop). But the "key excerpt" you are quoting is not, since it is about a single-dose of pfizer, which was known from the very beginning to be not nearly as effective as the two dose regime.