It does vary quite enormously. We have no idea when or where my husband was infected - and really, if we hadn't known, we'd have just thought he had a slight cold (and he is 71 now, so in a fairly high-risk age group). And why didn't I get it? Our flat is far too small for us to live separately within it.....

I did read that when someone flies in from abroad and goes to the test centre in the airport, it's not going to pick up any infection he might have picked up on the plane... and so it goes.

I hope your colleague, wherever and whenever they were infected, hasn't already spread it round the office! And that they get well quickly with no after-effects.