Random discussion of Covid-19 not specifically related to restaurants or food

I say bring in the experts in feedback control and let them weigh in on this. That’s all. My opinion is that it does have value in the area of epidemiology. And I’m a little surprised that no one has even talked about it in your meetings, because feedback control is being used now.

There are people talking about it in such meetings but they don’t see great value in it in the current situation. In addition, with so many easy unforced errors already made in controlling the pandemic, adding such “fuzzy logic” approach would be way too risky and unknown to kill even more people - until now you still haven’t explained how you want to avoid even a single unnecessary death with your approach when you even admit that it might be necessary to further “notch up or down” during the process. Wouldn’t you agree that this would be too risky already ?

I think that we’ve waited way too long to exert control, and that by the time we’ve taken action, there have been far too many new infections. “Notching down” wouldn’t exclude complete closures over the same (long) time period that “full open” was allowed. It would start reducing opening days much earlier, thereby reducing transmission earlier and saving lives that were lost due to the long delay before a sudden “full stop”. Re-opening would be similarly ramped upwards a notch at a time, based on feedback. “Full open” would be a goal. Just not instantaneous either way. So I see it as less risky, not more.

I would implement a nation-wide lockdown for 1-2 months (similar as it was done in many parts of Europe) to get the numbers to a similar level as in those countries. They will also get some setbacks in the future but it is obvious what really works are nation-wide lockdowns (which are actually enforced) to crush the curve.

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National lockdowns are a waste of time if there’s not a national plan for the next step.

Moved content has no context on this thread.

Completely agree but without a national lockdown there won’t be any next steps which would have a chance to be successful. Any future plans can only work if we get the infection, hospitalization and deaths rates drastically down nationwide now (before in 2-3 months the flu season will start and the problems will really start)

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Meanwhile, back in Japan:

https://www.bbc.com/news/world-asia-53188847

There are no definite conclusions drawn in this article, but it’s certainly a worthwhile read in the context of the discussion here.

You and Robert are both probably right, though. In the absence of a national strategy that’s widely accepted by the public, “asking” doesn’t work very well here.

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On the subject of engineering-level feedback control as it applies to covid, here’s a very interesting and relevant article from the highly respected IEEE.

Note the date.

That article seems to me to describe pretty much what California has been doing. They track multiple indicators for each county and have five stages from lockdown to fully open.

I think you’re fantasizing about a level of granularity that’s impractical given the many unknowns about the disease, inadequate testing and contact tracing, and rushing on Newsom’s part. No county should have been allowed to go from one stage to another without a month of watching in between. And the practicality of having different counties on different timetables is pretty dubious given the state’s inability to limit travel by irresponsible citizens.

Control theory is not unfamiliar to epidemiologists.

Good grief.

The whole point of a rolling 14-day average is to smooth out granularity in the data. When that rolling average shows a distinctly rising trend, as it did after June 19 in SD County, it’s not at all a granular change. But I agree that working out a practical way to modulate opening days or hours would need careful thought.

Having, say, ten stages of reopening rather than five would take more and better data.

Ten more closely-spaced stages would be a first step in the right direction, IMO.

I agree that more and better data are needed to inform decision-making. So whatever became of “pool” testing?

In SD, testing capacity (due to supplies) is stretched to the point that tests are now going to revert to only symptomatic individuals and health care personnel. Or mostly, anyway. The result will be a skewed and misleadingly higher reported positivity rate. I continue to believe in random testing of the overall population, but of course those with symptoms really should be tested. So how to interpret the data under these circumstances?

Perhaps a metric other than the rolling average “positivity rate” should be considered, such as the hospitalization rate, for deciding on the timing of incremental changes.

In my opinion, business closure formulas like those in CA that are based on localized outbreak clusters and prescribe a “step-function” shut-down that chokes off entire business sectors for semi-arbitrary fixed intervals (based only on max infection/recovery times), are simplistic, mindless B.S.

In SD County, the number of hospitalizations has indeed been increasing since the week of June 22, but the number of hospitalizations relative to active, confirmed cases has hovered at about 10% for months, as new patients have come and gone .Our excess hospital capacity headroom is still very good.

In any case, there has to be a better way to govern things than telling all of the people in targeted business sectors that they will abruptly have no livelihood at all, with one day’s notice or less.

And surely there has to be a better way to even out the pain, rather than abrupt full-open or full-closed (for three weeks), for some. I think most businesses would understand and go along with that as brotherhood in the larger community.

As a state and as a country we really have to come to understand that “full stop, wait period, full start” is unstable and costing lives and livelihoods.

Once again I’m going to suggest this article to all. The sample at the end illustrating instability with On-Off control is particularly salient. And this was published in mid-April.

It’s mostly a verbal discussion, very little math, about the history of covid controls and what might have been – and presumably could still be. Easy and interesting to read, and very clearly articulated.

[There are a many edits and additions in my posts sometimes because I “compose at the piano”. This one is a record, though.]

Testing as it’s done now, with a seven day delay to results, will find some people who are probably still infected, but not likely all. The “rolling 14 day average” of positivity rate helps to smooth this out to some extent, but I have two other issues with testing as it’s currently being done.

First, a given person’s test result may come back negative, based on the day they were tested. They could in principle become infected and contagious the very next day after their test without any form of detection.

Second, for now the people in SD County being tested are those showing symptoms (plus health care workers and high-risk individuals). Limiting those tested to this cohort will obviously result in a higher positivity rate among those tested, leading to decisions that could be excessively heavy-handed (abrupt “Off” and delayed “On”)

I see that the FDA has approved pool testing of up to four people, as of today. That’s a very good idea in my opinion, and the max pool size is probably OK. Even two people in a pool would greatly increase the overall test results rate (and might be even better than four because a pool size of two wouldn’t dilute the samples as much and would minimize false positive pools by the largest possible amount).

Perhaps two pools of two people each, one carried out in the manner done now (those in line) and the other fully randomized over the entire population, would be an improvement. The latter would give a snapshot of the actual amount of prevalence of the disease at a given time, IMO.

When the positivity rate is in single digits, a pool of two would be wasteful. E.g. if the positivity rate is 5%, that’s one out of 20.

WIth a group of four, for every 20 people, Quest does five tests, one comes back positive, they need to retest four, that’s a total of nine.

With a group of two, Quest does ten tests, one comes back positive, they need to retest two, that’s a total of eleven.

That needs to be adjusted slightly for false positives, but for a 5% positivity rate the sweet spot is still probably four tests.

Quest probably has a formula for this and they can just plug values into a spreadsheet to get the optimal pool size.

https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-issues-first-emergency-authorization-sample-pooling-diagnostic

I hadn’t run any of the math, so the numbers in your example are interesting – and especially germane in SD County because the positivity rate here is not far (at the moment) from the value you chose.

And yes, no doubt Quest has done their homework on this. (Well, at least I hope so.)

Wishful (on my part) statement by Dr. Fauci:

"The patchwork of out-of-phase, state-mandated controls has not worked in our country.

Based on all of the scientific and engineering knowledge available at this time, I am very strongly recommending that the governments of all states simultaneously institute the following state-wide policy as of Aug 1, 2020:

  1. Uniformly implement the science and engineering-based feedback controls that I and other epidemiologists and engineers have designed, evaluated, and endorsed. These regard highly flexible and responsive obligatory social controls enacted to control aggregate physical distancing; airborne transmission; movement and gatherings; and business operations. These measures will lead to our recovery in health and social-economic stability in the shortest amount of time. Specific details will follow shortly

  2. Discontinue all state- and locally-mandated controls in favor of the remedies that my Institute will specifically prescribe, in order to maintain uniformity and stability throughout the country.

  3. Adhere to all of all specific updates from our Institute which could be announced as frequently as twice a week; be watchful for these

Taking this unified nation-wide action now will reduce total US deaths from the covid and shorten the time for our personal, social, and economic recovery. I’m sure all will participate and cooperate because we all want this to calm down."

I wish our Covid Doctor in Chief would say something more specific like that, rather than just “wear a mask” and “wash your hands” and stand six feet apart. And in effect, “a vaccine in January is hopeful but only maybe possible. I hope. Cautiously.” And “yeah, things are gonna get worse”. Yada, yada, yada…