We've seen what B.1.1.7 does even when you're mostly locked down as it takes over.
What happens if it takes over and you're not locked down?
Let's check in on Ireland.
18 days ago, they were at 1/6 of our rate. Today, they're nearly double.
This is why the UK has to do a 1st-dose only strategy. This is why the UK has a harsh national lockdown.
And it's why we can't afford to screw up our vaccine delivery.
A few tragic notes:
At any point this summer, they could have taken a New Zealand strategy with very little effort. They had days with single digit case counts.
Unlike the UK, they rolled back their restrictions for the Christmas holiday. In retrospect, this was as B.1.1.7 was at about 25% and growing.
Despite the rapid climb, they went ahead with reopening schools on Jan 3.
Test % positive has jumped from 2-3% to 30%. That 30% means that their latest case counts are significantly underestimating the spread.
B.1.1.7 will increase its share about 6x monthly, but doesn't really move Rt until it approaches dominance. At < 10%, the numbers don't really change.
Remember, we only need 30% vaccinated to balance the lift from B.1.1.7 totally taking over. It will delay herd immunity, but that needs to be our first target to prevent meltdown.