Hi Lake1952.
We have been doing laboratory based antibodies on all our hospital staff every 28 days since last summer as it is the best way to check the hospitals are safe - if they are safe no member of staff will develop antibodies!!! Nevertheless we had 15% of staff positive from March 2020 who got infected before we put up defenses. These people did NOT get a greater response to the first dose, although a minority did to the second dose. I am sorry to appear to contradict you but it is important those who get symptoms do NOT take it that they have already been infected and stop safeguarding.
In terms of the older pilots, Pfizer did do phase 3 arms in those 65-75 and over 75. They found that even less older volunteers got infected compared to younger people, so it appears the Pfizer vaccine is effective in older people. I suspect they got less infections than younger vaccinated volunteers merely because they went out less and got less exposure to the virus. This is not proof as the Phase 3 studies were only designed to show that the vaccine at 2 doses at least halved the risk of getting an infection - everything else is a hypothesis or rubbish from politicians - but the ONS will have this data in a month or so.