The facts are in. When it comes to COVID-19, New York did it right.
Until today, I thought no state had a realistic plan for school re-opening. Today New York governor Andrew Cuomo offered the first sensible talk I’ve heard on the subject.
Because whether or not schools are open is a question that remains always open, and the answer depends on data. Everybody can watch the numbers, everybody can tell what the result will be if they get out of hand. Whether schools are open or closed can change from week to week, depending on how well the state handles the pandemic. Bottom line: if your state can’t keep COVID-19 under control, you’re not ready to open schools.
Key to their plan is that it is data-driven. They have selected a “green light” and “red light” test (green light means go, red light means stop) based on the positive fraction of testing:
The 14-day average positivity rate must be no more than 0.05 to set the light to “green.” Once you’re there, if the positivity rate rises as high as 0.09, the light changes to “red.”
I’ve suggested a similar idea based, not on the positive fraction of tests, but on the case load (daily new cases per million population). Here it is again, on a logarithmic plot:
I selected the “green zone” as case load no higher than 40 per day per million population. Based on New York’s choice, I would modify it this way: When the 7-day average case load is at or below 30 per day per million population, the light turns “green.” When it rises above 50, the light turns “red.”
I much prefer using the case load as a test statistic, rather than the positive fraction, because there are situations where the positive fraction can be low enough to suggest safety when the case load is high enough to contradict that. Despite my quibble, I am delighted to see a rational, data-driven metric used to set policy.
I’ll point out an addition advantage: it gives people yet another incentive to wear masks and practice social distancing. When you know that your business, your job, and/or your kids’ school depends on keeping the numbers down, you’ll work extra hard to keep the numbers down.
I haven’t seen enough of the next part of New York state’s plan, because after answering the question “IF” schools re-open, you have to say “HOW.” Much remains to be done, but I am at least encouraged that one state seems to be asking the right questions and making best use of the science.
Meanwhile, Florida is not in the green zone, they’re in the red zone. But governor DeSantis seems dead set on opening schools. He also seems dead set on clinging to the myth that Florida has things under control.
Pun intended.
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Open Mind 
“I much prefer using the case load as a test statistic, rather than the positive fraction, because there are situations where the positive fraction can be low enough to suggest safety when the case load is high enough to contradict that.”
Ok, now I see a crack in my earlier argument (where I disagreed).
New York State has around 19 million residents. Supposing all of them could be tested in single day, then an “acceptable” positivity rate of 5% would mean 950,000 residents tested positive. Not terribly safe.
Just a brief comment on your posting style, Billy. Your name is fairly new here, and you’ve said some things you’ve been challenged on, but in my view you have shown a tendency to listen to counterarguments and think things through a little more.
To come back and say “I see a crack i my earlier argument” shows a willingness to learn, to change your mind, and admit it. This behavior is nice to see, respected on good science blogs like this one, and will encourage others to engage in honest discussion with you.
Thanks Bob,
I enjoy the smart feedback.
So that last graph shows Florida now significantly worse than New York (is that city or state?) ever got. That’s ‘quite bad’ isn’t it? Is the problem concentrated in some cities in Florida or spread across the whole state?
[Response: That’s compared to NY state. Florida is raging all over the state.]
Re: HOW.
I listen to a podcast called “This Week in Virology”, a.k.a. TWiV. Top flight epidemiologists, immunologists, etc., gather via Zoom and discuss developments in Virology each week. Since the pandemic started, the topic is SARS-CoV-2 and Covid-19. A leading clinician who is supervising thousands of doctors treating Covid-19 patients in NYC starts off many of the podcasts with a short report on developments in Covid-19 treatment.
Some recent discussion on TWiV has been about how to open schools safely. The resident epidemiologists were very enthusiastic about what Colby College is saying they are going to do. Colby College has published its “The Plan for Returning to Campus”.
Colby says their plan is “guided by the latest scientific knowledge”, and the TWiV epidemiologists agree.