I will agree with you that the study’s wording is odd, and so can easily lead to confusion. But note that even in your post only vaccinated health care workers are mentioned. There is no mention of studying any unvaccinated folks.
And since unvaccinated folks weren’t studied, it is not proper to draw anything conclusions about them - based on this study, that is.
As a side note, it would have been nice if the researchers had also studied a few unvaccinated people while they were at it. That would have been most interesting.
Since this is such a hot button issue one can assume that the language used was proofed many times as not to be used in any other fashion than that was intended.
Given that it is reasonable to make that assumption here. which is there is an observed and significant difference observed as they eluded to the fact they did try to cross reference with other studies though scant as they are.
So no you can indeed feel confident that though not applied in the title correctly the articles conclusion is correct.
sorry took a phone call while penning that last sentence....in the previous post...lol