I suppose the thing about omicron being so transmissable, but apparently with some of the same weird anomalies as earlier strains, is that you can't be absolutely sure it was the contact they know about that was the point of transmission. It's a minefield - we've had people living in the same house as a positive person and never getting a positive LFT, and people who only left the house to go round a supermarket (masked) and have now had a positive LFT. Luckily, among people I know at least, it's proving to be fairly mild (which still means on a par with a very nasty cold/mild flu) so far. And numbers have finally started to go down here *sigh of relief*.