Agree with sirfredfredgeorge.
Also immunity from prior infections is likely to have more meaningful impact on transmission since people with the highest number of social contacts tend to get infected first. If you vaccinate a 90 year old retiree living alone and shielding from the outside world, you reduce their personal risk but you do not change transmission dynamics. If a 30 year old factory worker catches Covid, recovers and gets taken out of the transmission chain, he/she can no longer infect their colleagues. The impact on the R ratio is much more meaningful.