Post #1088: COVID-19 trend to 4/1/2021

Posted on April 2, 2021

No real changes from a few days ago.  The U.S. as a whole as a modest upward trend in new COVID-19 cases per day.  Five of the six regions have an upward trend.

Michigan now clearly has the highest rate of new cases per day in the U.S.  The large, oddly-shaped spike at the end of the line for New York (below) is due to a disruption of reporting by New York City, followed by a catch-up.  (Per the NY Times).

Cases are rising in almost all states in the Midwest and Northeast.

California and Florida remain stable.

The elderly continue to get vaccinated, although at a slowing rate.  Well over half the elderly are now fully vaccinated.  For the past two days, the increase in the fraction of elderly with some vaccination slowed from 0.35 to 0.30 percentage points per day, while the overall pace of vaccinations picked up to 3M/day.

The CDC updated its page on the proportion of the new, more infectious variants in the U.S.  It can be found at this URL:

For the two weeks ending 3/13/2021, their preliminary data show that the U.K. variant B.1.1.7 accounted for 27 percent of all cases.  

That means my “simple model” is running further and further ahead of reality.  And that seems to be because the doubling time for that virus is lengthening.  In this most recent period covered by the CDC, the doubling time increased to 13 days.  Not clear what might be causing that, but vaccination is a possibility.  Per the CDC data above, we’re almost at the point where 40% of the adult population has had at least one dose of vaccine.

Basically, my simple model is now well out of date, running far too fast, and I have to recalibrate it if I want to keep using it.

That’s also consistent with the most recent data from the Helix Corporation COVID-19 dashboard.  They show that maybe 57% of all U.S. cases were the U.K. variant B.1.1.7, circa March 27, 2021.  That information is available at this URL:

The CDC data (older, but more representative of the U.S.) and the Helix data (freshers, but possibly non-representative) appear to be in very good agreement.   That means that, as of today, the U.S. is almost certainly well beyond the point where the U.K. variant accounts for half of new cases.

The same Helix data show that about two-thirds of Florida’s cases were the U.K. variant, as of a few days ago.  And Florida appears to be stable.

I’d have to say, so far, so good.  I have no idea why Michigan appears to be so different from the rest of the U.S.  But I think that Florida shows that the spread of these new variants does not necessarily translate  into an uncontrolled outbreak and the need for further shutdowns or other invasive measures.