How often are you tested? It's absurdly unlikely to not have had it at this point, especially working with patients every day.
If this is their first exposure (shockingly unlikely, unless they're something of a hermit) then their immunity may have waned somewhat since then.
The second or third time I had COVID I only found out I had it because of work, I was working on a clinical trial with cystic fibrosis patients so we were getting tested daily before we went on site. This was maybe 6 weeks after my third vaccine. I tested positive but at no point did I display any symptoms whatsoever, not even a cough or a fever of any kind. Had I not been doing regular testing for work I would have had no idea I'd had it.
I wonder if they could be persuaded to start posting on here...
Yup. Little pang of sadness seeing it finally gone. I got years of procrastination out of that app.
That and crypto scammers. That's basically all twitter is now.