Virus in wastewater: nothing to panic about

Editorializing in COVID news

Vincent J. Curtis

29 Mar 22

RE: COVID-19 cases are on the rise again in Hamilton.  “Wastewater surveillance to monitor virus missing at key time.”  By Joanna Frketich.  The Hamilton Spectator 29 Mar 22.

Let’s ramp up the panic again!  And to make sure people get the message, the article contains the following bit of editorializing: “Hamilton is missing a key tool used by the province to as an early warning system.”  No, it’s not!!

First, let’s be clear.  This wave is already fizzling.  It’s not going to have legs.

Dr. Elizabeth Richardson is rightfully skeptical about the “missing tool,” viral count in wastewater.  There is no cause-effect relationship between viral load in wastewater and case numbers because one really sick person can put as many viruses down the toilet as ten slightly sick people.  The ‘virus in wastewater’ is too remote an indicator anyhow to what really matters to spend public money on it.  If it worked perfectly it would only forecast rising case numbers by less than a week.

What matters is hospitalization and ICU usage.  But rising case numbers themselves precede rising hospitalization by ten days or so; and ICU usage about a week after rising hospitalization.  So, case number is the important leading indicator.  Viral load in waste water is unreliable in forecasting verified cases, and if nobody’s sick enough to get tested, then they certainly won’t be hospitalized.

On viral loading, Dr. Richardson is right.  If there are people pushing for virus in waste water analysis, you have to wonder what financial interests they have in the matter.

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