COVID is Collapsing in Washington State: Just as Predicted!

Three weeks ago, there were fears that COVID was increasing again and Governor Inslee was thinking of backtracking on reopening the State.  

Local papers were carrying stories warning that herd immunity was impossible.

But a careful analysis of the numbers, as  >provided in my blog of May 1st, showed the opposite:  that Washington COVID cases were about to plummet.

And that is exactly what has happened.   

Consider a plot of Washington COVID cases from March 1st to May 16th below, showing both daily cases and a 7-day average (data from the WA Department of Health website).

The daily cases (and 7-day average) peaked in late April and then declined rapidly by roughly 40% through mid-May.  Note there is a weekly cycle of collection, with some days with better collection than others.

Washington State COVID is collapsing.  And it makes perfect sense.

If you read my earlier blog, the analysis started by trying to get a measure of the percentage of residents (of each state) that possessed antibodies to COVID,  This was done by adding the percentage vaccinated to the percent that was immune because of contracting COVID.  

You simply can't look at vaccinations alone, as some have done.  And to estimate the percentage with COVID immunity, I multiplied the number of reported cases by three, since there are many cases that are not reported or are asymptomatic.   There is strong support in the scientific literature for this multiplier, with several papers/reports based on serology data.

Then I compared this measure of the population's antibody rate to the change of COVID for the previous two weeks (last half of April) for all 50 states.

 I was stunned with the result.  Once my measure of COVID immunity got to roughly 70%, the number of cases collapsed.   A transition to herd immunity was occurring.

Oregon's cases dropped like Washington's:  Exactly as Expected

At the end of April, Washington State and Oregon were national outliers with rising cases, while the rest of the country had declining new cases of  COVID.  Why?  My index explained it all. WA and OR were LOW outliers in my index, mainly because our states had not had as many COVID occurrences.   Thus,  WA and OR were fertile grounds for COVID spread. 

But we were getting close to the 70% level and within days we would cross the magic number as vaccinations continued apace and plenty of folks (mainly young people) were getting COVID.

And it happened just like clockwork.

Our state crossed the threshold of approximately 70% total of my immunity index in early May and the state COVID case rate rapidly declined.  

And it won't be going up....both because increasing numbers are getting the vaccine (and, yes, some are catching COVID).  Plus, the warming weather is highly favorable, with people spending more time IN THE COMPLETELY SAFE outdoor air and opening their windows.  Plus, increased sunshine is a potent killer of COVID.  Only a radically different viral variant could change the story....and there is no hint of that at this point.

But what is happening now you ask?  

And is every country in Washington State showing declines?   The answer is no and that demonstrates the power of my approach.

Consider the ten most populated counties in Washington State.  Here are their corresponding immunity indices.  There are BIG differences. King and Yakima counties have the highest indices (about .7--70%), mainly because both had a lot of COVID cases.  But Whatcom and Clark counties are low--around .55.

So what happened in these counties the past months?  First, the counties with high values (over .7)

King County has been in decline all month.

And Yakima has been falling for longer because many COVID cases got them to .7 early.

Contrast their experience with Whatcom County, where the immunity index is low.  Rising well into May.  Same with Clark County.

I have looked at all counties in the State and the signal is clear:  once the immunity index gets to approximately .70, the case rate declines.

I could show you more, but the message is clear, an immunity index based upon BOTH past infection and vaccinations appears to be highly useful in explaining past COVID cases and provides a way to see into the future.    

Several epidemiologists contacted me after my first blog, and they supported my analysis.  And if any have any concerns with the above, let me know.   If there are flaws, I want to know them.

This is a good example of the scientific method:  creating a hypothesis based on data and then making a prediction based on the hypothesis (that COVID herd immunity accelerates when the immunity index gets to roughly .7).   If the prediction fails, one goes back to the drawing board. This time the hypothesis appears to be supported by new data.

My question:  why isn't the Washington State Department of Health doing such an analysis?