It's only by sheer coincidence that I learned I had it. In spite of testing twice (negative) after I developed a very slight cough following an event--which I wrote off to typical conference crud at that point--a couple weeks later I had to get tested before attending another event. (I had no symptoms of anything at that point.) And I tested weakly positive.

If I hadn't been attending the other (actually third) event, I'd never have known.

I believe that people who have been consistently super-cautious and generally avoided indoor crowds may have avoided catching it. But most people who travel, shop in sores, go to indoor events, etc. have probably had it even if they can't prove it.