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A Third Solution

paulbuchheit.blogspot.com

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Re: A Third Solution

#351

Post by hcknwscommenter »

joe_the_user wrote: post #343
mikepurvis wrote: post #290

Earlier quoted context omitted.

Hasn't that always been everyone's argument? That's the crux of Pueyo's "dance" [1], that as long as you've contained the initial outbreak, you can pretty much go back to normal if you track movement and have the capacity to test everyone who comes in contact with an infected person. [1]: https://medium.com/@tomaspueyo/coronavirus-learning-how-to-d...

This has been one major argument. The others have been: "flatten the curve - just extend the time until everyone gets it" (obvious problem, exponential growth can't work that way), "shelter in place 'till a vaccine appears" (not very practical) and "it's really not that bad, there are so many asymptomatic carriers that in the end it's not actually worse than the flu after all or at least there's nothing we can do." (…

""flatten the curve - just extend the time until everyone gets it" (obvious problem, exponential growth can't work that way)"

Huh? One goal is to flatten the curve so that we don't have exponential growth. Another is to flatten the curve so much that, even if might still be exponential growth, the growth is slow enough for our health care systems to absorb the peak.

Re: A Third Solution

#352

Post by nopinsight »

A very recent Yale study suggests promises for saliva-based detection:

“While saliva has shown promise for SARS-CoV-2 detection, very few studies have directly compared it to the current gold standard, nasopharyngeal (NP) swab. So, we compared NP and saliva samples from COVID-19 patients and self-collected samples from asymptomatic healthcare workers”

“COVID-19 patients: SARS-CoV-2 detection from saliva is comparable to (or better than!) NP swabs and more consistent over time ...”

“Plus, the detection of SARS-CoV-2 from the saliva of two asymptomatic healthcare workers (...and counting!) who tested negative from their NP swabs suggests that saliva could be a viable alternative for identifying mild or subclinical infections.”

https://twitter.com/awyllie13/status/1252996627217801218?s=2...

Re: A Third Solution

#353

Post by scythe »

argonaut wrote: post #329
scythe wrote: post #92

Earlier quoted context omitted.

If we assume (key) that the probability of becoming infected is directly proportional to the number of people you interact with, and consider that the probability of spreading infection given that you are infected is obviously directly proportional to the number of people you interact with, the product gives a quadratic function: [probability of becoming infected and spreading] = [probability of becoming infected] *…

This isn't quite right. For one, the probability of being infected is not linear (it's capped at 1). If you do the math, the expected number of people you infect (given you are not infected) is roughly linear-ish.

> the probability of being infected is not linear

Correct, it's not. But it is roughly linear in the limit of small numbers of people with a small constant probability of becoming infected per interaction. (This assumption becomes problematic when you see "clustering" of highly social people with other highly social people.)

To be specific, if P is the probability of becoming infected when interacting with a single person, then the probability of becoming infected after interacting with N people is 1-(1-P)^N = NP - O(N^2 P^2). It's easy to see that the limiting infection probability is 1 in this simplified model, and that if N*P < 1 you're looking at close-to-linear growth.

Re: A Third Solution

#354

Post by tempestn »

clairity wrote: post #199
tempestn wrote: post #70

Earlier quoted context omitted.

Exactly. While this plan would certainly result in some disruption, it would be a lot less than the current status quo. And you can't really compare it to simply "opening back up" without a plan like this, because the simple fact is that even without government-enforced lockdowns, many (perhaps most) people won't return to a normal level of activity if they don't feel safe doing so.

> “...because the simple fact is that even without government-enforced lockdowns, many (perhaps most) people won't return to a normal level of activity if they don't feel safe doing so.“ you’re underestimating the pain that many americans are feeling after just a few weeks of (soft) lockdown. it’s not that people want to be unsafe, it’s that their livelihoods are in grave danger if the lockdowns last for months. many…

All the more reason why extensive testing, allowing them to go back to work safely, would be great!

Re: A Third Solution

#355

Post by anon9001 »

joe_the_user wrote: post #343
mikepurvis wrote: post #290

Earlier quoted context omitted.

Hasn't that always been everyone's argument? That's the crux of Pueyo's "dance" [1], that as long as you've contained the initial outbreak, you can pretty much go back to normal if you track movement and have the capacity to test everyone who comes in contact with an infected person. [1]: https://medium.com/@tomaspueyo/coronavirus-learning-how-to-d...

This has been one major argument. The others have been: "flatten the curve - just extend the time until everyone gets it" (obvious problem, exponential growth can't work that way), "shelter in place 'till a vaccine appears" (not very practical) and "it's really not that bad, there are so many asymptomatic carriers that in the end it's not actually worse than the flu after all or at least there's nothing we can do." (…

> "flatten the curve - just extend the time until everyone gets it" (obvious problem, exponential growth can't work that way)

Just to nitpick a little here, it's more like "flatten the curve - stretch the time while everyone gets it, so we don't overwhelm hospitals". Even with exponential growth, you would rather deal with it over a longer period than have a massive spike where all services are overwhelmed.

Re: A Third Solution

#356

Post by [deleted] »

tmsh wrote: post #135

If the proposed test takes 10 minutes, as Steve Jobs would say, that's not good enough. Try to make it work in 10 seconds. Like a breathalyzer. Add more liquid to the solution if necessary. I am not a doctor, but am just imagining TSA-style x-ray detectors that you walk through, while issued a disposable container to blow into, and put back into the large spinner machine. A quick search actually reveals something: ht…

[deleted]

Re: A Third Solution

#357

Post by vikramkr »

IdoRA wrote: post #275
predxionbio wrote: post #255

Earlier quoted context omitted.

Hi, Walker here, one of the PreDxion co-founders. Up until recently we've been focused on developing our technogy as a point of care biosensor for us in patients experiencing dysfunctional immune responses (e.g., sepsis, ARDS, and the immune responses induced by certain cancer immumotherapies). The technical implementation of a viral detection assay is much simiplier to implement than our quantitative, multiplexed sm…

What TRL are you at for the original POC test, and what TRL are you at for viral detection? Any published papers for viral detection?

Are TRLs usually used outside of government R&D related things? If they got an SBIR I guess they'd be familiar with the technology, but I'm only familiar with it because of DoD funding applications and stuff, it's not terminology I've seen used in the private sector too much. Maybe it is, I'm curious to know if that's the case. I've usually only heard stages of tech development discussed in terms of preclinical, clinical stage, and other regulatory frameworks rather than tech readiness level necessarily.

Re: A Third Solution

#358

Post by aheilbut »

predxionbio wrote: post #282
lvs wrote: post #232

Earlier quoted context omitted.

How is chip fabrication is more scalable than plastic 384-well plates and cotton swabs? Nothing shy of a home pregnancy test is more scalable than qPCR.

Great question. This is one of the implementations we're actually developing. One of the challenges with the implementation of testing on this scale is not necessarily on the technology/assay but on implementation. How do you reasonably test millions of folks each and every day, or said another way actually get millions of nasal swabs, saliva, etc on 384 well plate? I think our ultimate approach is much more akin, al…

50 or 100 sites, each with say a few dozen liquid handling robots. Let’s say each site runs 200 plates per day.. doesn’t seem unreasonable. The only hard parts are the funding and regulatory requirements.

Re: A Third Solution

#359

Post by amirhirsch »

predxionbio wrote: post #278
zmmmmm wrote: post #212

The post refers to an alternative method of testing for COVID-19 based on surface plasmon resonance that would have significant advantages, but unfortunately it provides absolutely no real substantiation that the test exists or works. The link about surface plasmon resonance goes to a generic Wikipedia page, the link about saliva is a small scale study that was conducted on RT-PCR not surface plasmon resonance, and t…

Hi, Walker here, one of the PreDxion Bio co-founders. Heres a some more information on the technology underlying the test we are developing: https://pubmed.ncbi.nlm.nih.gov/25790830/ . Unfortunately, up until about a month ago us like many folks, were blissfully minding our business developing a rapid point of care cytokine detection platform for use in monitoring patients experiencing certain immune responses follow…

I worked at Integrated Plasmonics in 2012–14, the major problem you will face is fluidics and sample handling not so much the sensor design. You should consider stochastic plasmonic features grown using dna self-assembly on the surface of a cmos sensor (lots more recent work on DNA-based plasmonic nanostructures). I worked on varieties of ways to characterize a chemical signal even from stochastically distributed plasmonic features by running calibration during manufacturing. We were able to use support vector regression to characterize known chemical reaction signals on a per sensor basis.

Re: A Third Solution

#360

Post by johncalvinyoung »

taneq wrote: post #345
behnamoh wrote: post #340

Earlier quoted context omitted.

Ever since 2000, we've have a pandemic once every decade. The next one will occur soon, but it's not certain whether it'll be as scary as COVID-19. > We need to start building social distancing into our culture the same way we built protection for sex into our culture. While I agree with the general gist of your comment, I should emphasize that what we need is physical -distancing, not social . Humans are social bein…

> I should emphasize that what we need is physical -distancing, not social. Good distinction. We should be focusing more on hygiene while finding ways to connect remotely with the people who are important to us.

> while finding ways to connect remotely with the people who are important to us

Good stop-gap, but not remotely viable long-term. Humans aren't made for isolation, even if video calls help take the edge off soon. FaceTime and Zoom have a significant cognitive load, too. As long as we're talking about how society should adapt to this sort of risk, we can't just go to living in individual hermetic pods with internet connections. The mental health cost will be monstrous.

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