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Tornus — LessWrong

This stuff is super hard.

I'd recommend (with reservations) Consent Academy, who do a lot of training on incident response, accountability processes, etc. They're good folks who have figured out a lot of really useful things about doing this kind of work.

Their classes can sometimes get pretty rambling and theoretical, but I've learned a lot from them.

Replying toMERV Filters for Covid?

Tornus4y

MERV Filters for Covid?

Strong work: thank you!

I believe there's a small mistake: in the first table (after "In equilibrium, we see the following amounts of sars-cov-2 relative to no filtration:"), I believe the second column should be labeled "presence", not "reduction".

Replying toHow Big Are Covid Particles?

Tornus4y

How Big Are Covid Particles?

Lots of cool data here—thank you!

(Edited to remove a comment based on misremembering the Most Penetrating Particle Size)

Replying toLong COVID risk: How to maintain an up to date risk assessment so we can go back to normal life?

Tornus4y

Long COVID risk: How to maintain an up to date risk assessment so we can go back to normal life?

I'm overdue for making another pass through the latest data, so my opinions on this are weakly held. But briefly: my current thinking is that many people (including Zvi and me) have made the mistake of conflating a number of different phenomena into the single category of "long covid". I believe Zvi is correct that if a large number of people were suffering long-term debilitating impact, we'd know it.

I suspect that after I plow through the data again, I'll update significantly in the direction of believing that:

"Long covid" is a debilitating phenomenon that affects a very small number of people for a long time.
"Post-acute covid" is significantly impactful and impacts a non-trivial

Tornus4y

Long COVID risk: How to maintain an up to date risk assessment so we can go back to normal life?

Eliezer, back in 2009:

Yet there is, I think, more absent than present in this "art of rationality"—defeating akrasia and coordinating groups are two of the deficits I feel most keenly.

This is not a small project, and I'm too new here to have a clear sense of how it might happen. But this feels important.

Replying toLong COVID risk: How to maintain an up to date risk assessment so we can go back to normal life?

TornusMay 08, 2022

Long COVID risk: How to maintain an up to date risk assessment so we can go back to normal life?

To more directly address your initial question: to my mind, Zvi's analysis isn't obviously wrong, but it's pretty far to the optimistic end of what I see as the reasonable range.

My best model suggests that for me (55 but very healthy), 1,000 µCoV of risk has an expected life cost of about 15 minutes.

Based on that, my approach to risk is very situational. Is eating in a restaurant worth 75 minutes of lying in bed with flu wishing I was dead (based on today's numbers)? No, it isn't. Is going to a friend's wedding worth that? Yes, it probably is.

Replying toLong COVID risk: How to maintain an up to date risk assessment so we can go back to normal life?

TornusMay 08, 2022

Long COVID risk: How to maintain an up to date risk assessment so we can go back to normal life?

I'd love to see a more structured approach to the kinds of questions you're raising here. LW does a good job of creating a space for smart people to share their thoughts about individual topics, but isn't so good at building toward a coherent synthesis of all those pieces.

The original microCOVID white paper did a good job of summarizing a lot of relevant evidence back in the day, but (like the rest of the site) has been only sporadically updated.

Put me down as tentatively interested in being part of some larger project, if one comes together.

Also: may I humbly request that if this ever takes off, it be named LessSick?

Replying toHome Antigen Tests Aren’t Useful For Covid Screening

Tornus4y

Home Antigen Tests Aren’t Useful For Covid Screening

That all makes complete sense.

And yes, the specifics of the population make a huge difference. Honestly, I think that accounts for the breadth of my estimate range more than uncertainty about abstract test performance does.

Replying toHome Antigen Tests Aren’t Useful For Covid Screening

Tornus4y

Home Antigen Tests Aren’t Useful For Covid Screening

I think it's important to emphasize that antigen+ people are much more contagious than antigen-. It's hard to quantify that, but based on typical differences in Ct value, it's probably a very substantial difference (factor of 10+?).

You're absolutely right that the reference class is the key issue (if there's one thing I've learned from hanging out with epidemiologists, it's that they're always grumpy about people using the wrong denominator).

In a perfect world, where everyone with any symptoms whatsoever stayed home and was scrupulous about following what the CDC exit guidance ought to be, antigen tests would be significantly less useful. But in the real world, people absolutely go out when they have... (read more)

Replying toHome Antigen Tests Aren’t Useful For Covid Screening

Tornus4y

Home Antigen Tests Aren’t Useful For Covid Screening

Let me give you two answers for the price of one:

FDA and others have been very clear about this: you should use the tests as directed.
I (a decades-long amateur epidemiologist who's done a deep dive on antigen test research), my partner (a medical epidemiologist who works full-time on Covid), and several other epidemiologists I'm aware of, all use throat + nasal swabs.

I wouldn't worry at all about false positives: they really haven't been an issue with antigen tests. If I got a positive from a throat + nasal swab, I'd follow it up with a nasal-only swab or a PCR, just to be sure.

There is non-zero risk that you'd get false negatives, by some unknown mechanism. That seems unlikely given that some countries like the UK use throat swabs, but it's possible. It's my well-informed but not data-supported belief that the benefit of swabbing your throat probably exceeds the downside.

Book Review: The Righteous Mind

Tornus

I was inspired to read Jonathan Haidt’s The Righteous Mind by Julia Galef’s excellent interview with him. It’s an outstanding book that greatly improved my understanding of how humans understand morality and how to make moral arguments that humans will actually listen to.

More generally, I think it sheds some light on the challenges we face as we try to build a culture that is rational and ethical but still resonates with real humans.

Epistemic status

“All models are wrong but some are useful.” - George Box

Righteous Mind is a layperson’s introduction to Moral Foundations Theory, which as far as I can tell is broadly consistent with mainstream moral psychology but is just one of... (read 2051 more words →)

Why is Covid Surveillance so Hard?

Tornus

Why is Covid Surveillance so Hard?

Following up on a recent thread, I want to discuss how Covid case numbers are generated. I think this is interesting not only because Covid is interesting, but because it’s a good example of non-obvious real-world complexity.

A reasonable person might have a mental model of surveillance that looks something like this:

A person takes a Covid test
The lab enters the result in a state-wide database
An automatic process runs a database query once a day
Yesterday’s cases show up on a pretty chart

That model is completely wrong.

This is a brief overview of some of the challenges involved in Covid surveillance: the situation is far more complicated than I’m presenting here.

Organizational

... (read 1097 more words →)

Rapid Antigen Tests for COVID

Tornus

Update 2022-01-07: It's pretty clear now that antigen tests are less effective against Omicron, probably for three reasons: they are less sensitive to Omicron, viral loads rise faster with Omicron than with Delta, and Omicron is more infectious than Delta.

Based on the current data, I'm changing two things in the original writing, with the caveat that these are just guesses that are not backed up by hard data:

The test validity window goes from 12 hours to 6 hours.
The likelihood of detecting a person who is infectious but asymptomatic goes from 75% to 50%.

Personally, I've started using the throat swab technique: https://www.youtube.com/watch?v=5qHTBlxfNes That technique was likely more effective for detecting Delta, and there... (read 2327 more words →)

Interpreting Diagnostic Tests

Tornus

Most people—including most physicians—don’t understand how to correctly interpret diagnostic medical tests.

Here’s a concrete example: the BinaxNOW home COVID test has 68% sensitivity (chance of giving a positive result if you have COVID) and 99% specificity (chance of giving a negative result if you don’t have COVID). So does that mean positive test results are 68% accurate and negative results are 99% accurate? Unfortunately, it isn’t that simple.

My COVID risk level means that for me, a positive test only has a 6% chance of being accurate but a negative test has a 99.97% chance of being accurate. Your odds might be completely different, depending on your risk level.

In this post, I’ll... (read 824 more words →)