I didn't get into this question in the weekly post. The answer does not seem obvious to me.
Eventually, it will be obvious either way. Either the strain will spread rapidly across many locations, or it won't. But we would like to get the information as fast as possible, whatever the answer turns out to be. So the open question is, what numbers or other information can we use in the short term to generate useful evidence for or against the new strain being a lot more infectious than older ones?
The obvious first things to look at are England's case numbers, and how rapidly the new strain continues to outcompete the old strain. Certainly the percent dominance continuing to go up, or stabilizing, is evidence.
Alas, tonight is Christmas, and I haven't been keeping up in detail with English reporting and testing dynamics. We saw only a small bump on Christmas Eve, after big jumps in the previous post-announcement days, and I can't tell how much of that was the holiday. Same will apply to today's number, to Boxing Day, and then there are issues of either lag or catchup, and then New Year's. Can anyone shed light on these details, and how seriously we should take them? Even if we get a new mix of strain results, should we worry about lags in the south versus the north, where different strains dominate, warping numbers?
What are good data sources to check for the strain in other nations? Who is checking enough that if it was present, we would notice, or we'd have a good handle on its numbers? Can we make this data happen somewhere? 'Has been spotted in' isn't much to work with.
Also making this a place for people to say how they're updating their estimates based on information that comes in.
Can't update on #4. Of course a rapidly growing new strain will have a negligible impact on total numbers early on; it's a question of whether it will dominate the total numbers in a few months.