Scotland has vaccinated 99% of all care home residents and 93% of all over-80s: https://www.gov.scot/publications/coronavirus-covid-19-daily-data-for-scotland/
England’s world-beating system claims 90% of all ‘eligible’ care home residents but has, according to Channel 4, managed only 80% of all care home residents and 88.1% of over-80s. Worryingly for any attempts at future relaxation of lock-down, London has only done 74.9% of its over-80s.
From the World Health Organisation:
The percentage of people who need to be immune in order to achieve herd immunity varies with each disease. For example, herd immunity against measles requires about 95% of a population to be vaccinated. The remaining 5% will be protected by the fact that measles will not spread among those who are vaccinated.