What ultimately matters is if the hospitals can handle the load, delta is problematic because it produces new cases more quickly even among vaccinated and a sufficiently large number ends up in the hospital for it to become problematic. Both of these are demonstrated in Israel without invoking any kind of statistical analysis. Qualitatively the vaccine alone does not work well enough to lead to an R0 < 1, even when the most susceptible people are almost all vaccinated. I think that is super disappointing and at the same time I think it is really worrying that some politicians have not got that message in Germany / other places.