When COVID actually hit we basically locked down our house and didn't allow anyone in for the next two years. When I went out, especially the first year I always wore gloves and a mask wherever I was. My wife and I both got our COVID shots in February and March of 2020, so we were about as protected and isolated as we could be.
Since then, I've made sure that I've stayed current on boosters and I still mask up every time I leave the house to go anywhere. She has not had any of the boosters because I can't get any place to get one.
However, we have relaxed the visitor situation although there have been times when her son and daughter-in-law who live close have not been able to come because they did have COVID or had traveled and been exposed to COVID.
All this resulted in a couple of years of pretty severe isolation for both of us. And probably hastened her mental decline in a sense because she had very little interaction with real people except me. I did buy an Amazon Echo 8 so that those in her family who had the technical ability could drop in and visit with her in the video call. That turned out to be a really good idea.
Bottom line is neither one of us has had any kind of illness since COVID started, in fact neither one of us has had any kind of illness in the last four or five years. I do feel that if she caught COVID it would probably be the end for her.