During the vaccine trials, the test population was never tested for covid unless they developped symptoms. So you can't infer any information on whether the vaccine provided immunity against the virus (as in you won't get infected if you are vaccinated), or whether the vaccinated population got infected (and were possibly contagious) but without symptom. For that it would have required to test for covid the full test population regularly.

Claims that the vaccine provided immunity were always baseless. What the trials demonstrated was that the vaccine was effective at suppressing symptoms and hospitalisations.

And this is not something that came after the fact, I remember that this approach was discussed on HN when the results were initially published.