Post #1007: Below 30 new cases/ 100,000 / day, and projecting the impact of the U.K. variant

Posted on February 14, 2021

The seven-day moving average of new COVID-19 cases per 100,000 / day is now just below 30.  We’re now down 62% from the early January peak.



So far, the decline still appears to be going on at a steady rate.  Virtually all states show continued declines, and virtually all show them at a rate of about a 20% decline new new cases per week.




If the most recent estimates of the U.K. variant bear out, that will change over the next few weeks.  Below, I’ve taken some of the data as presented in the full version of “Genomic epidemiology identifies emergence and rapid transmission of SARS-CoV-2 B.1.1.7 in the United States“, and done my best simple-minded extrapolation.

This simulation only looks at the projected growth of the U.K. coronavirus variant.  It does not include any offsetting effects for the increasing fraction of the population that will be immune to COVID-19 via either prior infection or vaccination.

What that in mind, this table just extrapolates current growth rates, as estimated in the scholarly work cited above.  Right now (“You are here”) we’re shown as having 32 new cases / 100,000 / day.  That would continue to fall, but at an ever-slower rate, reaching a minimum of 20 / 100,000 / day in the second week of March.  At that point, the U.K. variant then becomes common enough to begin driving up the new case rate.

This is a rapid enough change that if it plays out as modeled above, it will be readily visible in the graphs a few weeks before we actually hit the end of the U.S. third wave.  The upshot is that we only have another two or three weeks before we ought to know, one way or the other, whether this is an accurate projection of the future.  Or, whether other factors — increasing immunity in the population, “seasonality”, or possibly the post-Super-Bowl “explosion” of cases — will put us on a different course.

I would say that the only sure thing, in this projection, is that by the time we should be able to see any Super Bowl effect in the data — no earlier than the end of this week — the popular media will have forgotten about it.