In healthcare, we often talk about "number needed to treat," or NNT, per outcome obtained or event avoided. (In diagnostics, the equivalent metric is "number needed to test," also NNT.
While I am sure experts vary in their calculations, see a tweet from former biopharma executive Dr. Thomas Wilckens (here), pointing to a new article by Prof. Hermann Brenner of Heidelberg on number needed to vaccinate per death avoided in COVID - article here.
He argues that NNV in COVID is as low as 8 in the institutionalized elderly, to 167, in relatively healthy 65-74 year olds, to 12,873 in the low risk population < 65. He also calculates that 99% of deaths avoided are reached with 33% of population vaccinated (being older or higher risk).
The paper is open access.