It was certainly discussed that we can't know how long the protection from the vaccines will last. But it also didn't matter much as we needed the protection now, and even a waning protection later is much better than no protection at all.

There were various studies about how the vaccines affected transmission of COVID-19. You don't need unethical studies for that, you can still get that data by observation. The data is a bit noisy as it's affected by all kinds of confounding factors. But we had that data at various points in time. One big problem was that the variants affected that enormously, so the data was out of date at some important points. This was also discussed a lot in the media.

There were various arguments around vaccine mandates that seemed to have missed the memo on the transmission studies for Omicron. This was still discussed in the media, though I found it very annoying that bad arguments were made here by people that should know better.