Vaccine efficacy is not "yet unknown." It's literally the most studied scientific question in the world right now, and possibly ever, with billions of data points.
The overwhelming majority of new cases are among the unvaccinated by a tremedous margin. Adding "exclusively" to the end of the sentence just repeats the same nonsense: that the vaccine is not perfect. There are breakthrough cases, but they are quite rare and remain so, perhaps not as rare as was hoped, but still rare. Verifying this fact takes mere seconds:
After the COVID-19 B.1.617.2 (Delta) variant reached predominance, fully vaccinated people had less risk of infection, hospitalization, and death.
www.cdc.gov
There was a time not long ago where there were 20x more infections in unvaccinated than vaccinated, that number has diminished but it is nowhere near 1. It is several times more than that. Those numbers are not close.
A year ago, we were all hoping for a 60 or 70% effective vaccine. It sounds like you wanted a 100% effective one. I never thought there was going to be a vaccine at all for a coronavirus, so I'm thrilled that it's way more effective than I expectd.