The Boston-area Covid sewage RNA counts have not improved in a year

I’ve been copying the Covid RNA-in-sewage measurements from the MWRA’s website for a few years now, mostly so I could replot it on a log scale, but also to answer (vaguely, sort of, with caveats) questions about how we are doing.  The short answer is we are not doing any better than we were last year, and have been behind more or less since mid-December.

This is the spreadsheet.

 

As a guide, since it has grown columns over the years, the MWRA’s data appears in columns A through I.  It is color-coded to show intensity, yellow is pretty common.  The two columns that matter are D and E, which show the geometric mean of the last 7 days reported for the South and North sewer systems.  7 days includes each day of the week, so it avoids weekend/weekday effects.  Geomean is used because it smooths out the noise in a process that grows exponentially

I experimentally also compute the median of the last 7 days, in columns J and K.  This is another way of smoothing out noise.  The weekly growth ratio, computed from the median, is in columns L and M, color coded with 1 is white, below one blue (blue is good!) and above one red (bad).  I further smooth this in column N; the compounding of 7 day smoothing means this is a lagging indicator ( 7 days total).

In columns O and P, is the ratio of the MWRA’s computed geomean, with the same date a year ago, for South and North sewer systems.  Same color coding, blue is good, red is bad.  At least one of the two systems has been above one every day since mid-December 2023 (it is mid-April now).

It’s not certain that RNA counts are exactly comparable after a year’s time, given changes in the infected population and changes in the virus itself.  Nonetheless, this is about the best data we’ve got, in terms of continuity and unbiased sample (everybody poops), and it says we’ve not made any progress.  It seems odd that so many people are ready to act like we have; if they could point to some data to support their claims, that would be nice.

(Yes I have heard of one paper reporting that the virus strain du jour overexpresses in sewage.  That’s one paper.  One.  How lucky do we feel, after a million-some dead?)