@Meowser72 prior to 2020 people were actively encouraged to go into work if they had a 'sniffle' or mild flu. Adverts for things like Lemsip sent the message that you can take a pill and get on with your day, flu or not. I'm willing to bet the house that you yourself went to work/got on public transport/went on a trip with a cold, cough or worse at some point.
The fact is that all these things always had the potential to make immunosuppressed people (like me) extremely ill. DH's colleague who he sat next to in January 2019 had a nasty dose of flu, which he brought home, gave to me, and I was very ill indeed.
You say the world has changed - maybe for you. For those of us who are immunosuppressed, it's business as usual but with one other thing to watch out for.
Thing is, I would never have called anyone selfish prior to 2020 for simply going about their lives, and neither would I now. Earning a living, going shopping, socialising - none of that is selfishness. It's just normal, human activity. And if everyone was happy to do it prior to covid, why shouldn't they be now?
I've had covid five times (and I'm a size 18 with high BP, so you'll be fine OP). I'm also quadruple vaxxed, so I've never been particularly ill, never needed medical intervention. I was a lot worse with flu.
It's time to quit it with all this 'selfish' crap. Seriously.