> Two doses of the Pfizer vaccine had an effectiveness of 93.7% at preventing symptomatic alpha infections, and 88% for the delta variant.
[..]
> However, the effectiveness of the vaccines plummeted if a patient had only received one dose of either vaccine: the study found both to be just more than 48% effective against alpha and only about 30% effective against delta.
I'm a little confused as to what your point is? The vaccines are highly effective after two doses, but not very effective after only one dose.
50% (48%) is for Alpha (I'm actually a little surprised it's that low; IIRC it was a lot better in the initial studies, though those were on the ancestral variant, not Alpha). For Delta, it's 30%, per that article. I'd call that pretty low.
That said, other studies are available, and some have shown decent performance against Delta after one dose.
https://www.forbes.com/sites/carlieporterfield/2021/07/21/st...