The evidence is mounting of vaccine and pre-infection evasion with omicron.
The UK Health Security Agency looekd at 581 people globally with confirmed omicron and they see reduced vaccine effectiveness with both the Astrazeneca and Pfizer vaccines against mild disease.
In lab experiments, they see decreased neutralization by 20-40x compared to the original virus and 10-20 compared to delta.
I don't think any of this is new information for markets. The bulls are hanging their hats on the idea that it leads to mild infection and that it might rip through the entire globe at a very rapid pace, offering some immunity to everyone. I think even if that means there's a short period where hospitals are overwhelmed and the sick can't be treated, then it's a net positive (as grim as that sounds).
Since this update, cable has been surging higher but I think that's more due to the clock than due to this news, which doesn't reflect anything new about GBP. There's also positive Brexit/Irish border talk doing the rounds but I don't think the market cares about that either. In any case, GBP/USD is at a session high, up 45 pips to 1.3264.