On the over 80's, don't we have the situation where no-one who was in hospital or under treatment for anything else would've been vaccinated (Like Captain Tom), and also no care homes where there was an active outbreak would've had any vaccinations.
And those are the over 80's most likely to be exposed to the vaccine, and hence still very likely to become a case, as they were before vaccination. The community over 80's who have much lower chances of being exposed to the virus, are the ones who were vaccinated, and care homes where there was no virus - so only the care homes where it was introduced after vaccination would be seeing if vaccinated exposure made a difference.