Hm, no, I didn't change anything.  The section headings are meant to indicate which transmission method those studies decided was substantially responsible for spreading colds.

@bhauth emphasizes the difficulty of studying transmission of "colds" because there are over 200 different virus strains responsible for what we consider "a cold", in response to my recent post.

I want to dig into the question of feasibility a bit more:

But it's not feasible to do human studies of so many virus types - consider how hard it was for society just to realize that COVID was transmitted via aerosols!

Ok, but why isn't this feasible?  Certainly it's the case that nobody has tried, but I don't think it'd be prohibitively expensive, at least on the scale of medical research.

Some quick back-of-the-envelope math...

How much would it cost to find and pay qualified volunteers for challenge trial like Dick et al., 1987 today?  My guess is that this is doable for $7k per volunteer^[1].

How many volunteers would we need?  In the pessimal case - the one where we're actually just going to test every single virus strain separately, rather than doing something more sensible^[2]...

My off-the-cuff guess is that 300 volunteers per virus would be enough to draw quite strong conclusions, with good experiment design^[3].

That's 60k volunteers, for a $420m price tag, not including other study costs.

Housing, feeding, and otherwise taking care of each participant - idk, let's be conservative, and call it $300/participant-day?  If we're going with ten days per participant that's $300 * (60k * 10) = $180m.

Clinical staff costs - conservatively, 2-3 hours per day per participant, but mostly not the super-expensive PI time, but mostly RNs/coordinators/etc.  Maybe $250/participant-day?  $250 * (60k * 10) =  $150m.

Lab work costs - I think you get a lot of benefits of scale, here, but let's say $2k/participant, so $120m.

I have no idea how to get accurate numbers for how much it'd cost to manufacture enough GMP-grade virus stock for each virus; LLMs converge on a $1-5m range per virus.  Unfortunate, but even at the top end, that's $1.5b.

$420m + $180m + $150m + $120m + $1.5b = $2.37b.

And this is the dumb brute-force solution!  Now, maybe it actually turns out that they're all different and nothing generalizes, so that mechanistic investigations into figuring out if we can predict a given virus's transmission methods without running a full human challenge trial on it, say by looking at its physical features, just doesn't work.  I still think that a sane civilization smashes that button for a couple billion dollars.  Are there higher priorities?  Sure, we should do those too.

1. ^{^}

   A COVID challenge trial paid volunteers $6200 in mid-2021, but the viruses we'd be testing are in-expectation substantially less harmful and unpleasant than COVID, especially the variants that existed at the time.  Some of the difference will be eaten up by sourcing costs, though.

2. ^{^}

   Like testing a smaller number, looking at those results, coming up with mechanistic hypotheses that try to explain why [virus x] spreads effectively by transmission method [y] but not [z], ideally ones where we can try to falsify them more cheaply than running a full human challenge trial, and repeating until we actually understand how particular viruses spread (to the point where we can make reasonably accurate predictions about future viruses based purely on their physical characteristics, or other easily-testable traits), rather than just knowing the mere fact of their propensity to spread via some method.

3. ^{^}

   Though I'm not sure how establishment-compatible it is. 

Yep, that is a big question mark that I note in the conclusion:

Might depend on details of specific viruses, and I don't think we've done enough research to have meaningful evidence about whether different RVs have very different transmission profiles from each other.

(And also implicitly in a few places within the body of the post.)

I think it'd be reasonable to apply a large discount to any updates you'd otherwise make on the question of rhinovirus transmission from this post, at least absent a follow-up investigation re: whether they behave similarly or not.

The humidity thing is a good catch.  I think there might've been one or two studies which investigated some related questions and reported some information about humidity, but I didn't go very deep on them.  Maybe a mistake!

Though also hard to square that with dry winter conditions being prime cold and flu season.

Yeah, that's an interesting consideration which came up in discussion with someone yesterday.  Another possibility is that people congregate indoors more during wintertime, but I haven't looked into that specific question.  (It wouldn't surprise me if someone had looked into it during COVID.)

I could also imagine it being the case that viruses are much less likely to be transferred from one patch of dry skin to another patch of dry skin via normal contact, than they are to be picked up by whatever mechanisms are used in various studies to check for the "presence" of viruses on surfaces.  In several cases, this was approximately "dip fingers into some kind of liquid solution, then culture whatever was picked up in that solution".

Unfortunately, the disinfectant results from Gwaltney & Hendley, 1982 point in the opposite direction:

Spraying of contaminated tiles with a commercially available phenol/alcohol disinfectant reduced (p = 0.003) the rate of recovery of virus from the tiles from 42% (20/47) to 8% (2/26). Similarly, the rate of detection of virus on fingers touching the tiles was reduced (p = 0.001) from 61% (28/46) with unsprayed tiles to 21% (11/53) with sprayed tiles. Fifty-six per cent (9/16) of the recipients exposed on three consecutive days to untreated tiles became infected while 35% (7/20) touching only sprayed tiles became infected with rhinovirus (p = 0.3).

The reduction in lab detection of viruses from the plastic tiles after being sprayed with a disinfectant (and then left to dry for 10 minutes) was much larger than the reduction in people getting sick after rubbing their fingers on the disinfected tiles (vs. non-disinfected tiles), and then rubbing their eyes/nose.

I expect this sort of thing to be quite sensitive to object-level details, and the sample sizes here aren't huge.

Now, you might think "Why not bring the deadline back to like 8pm, so that people have the night off?". But that's kind of antithetical to what Inkhaven is here to offer. Should I just cut out 4 hours of their day where they can't write? I assure you, they wouldn't spend the late hours precociously working on tomorrow's stuff. They selected into being the kind of people who needed an externally imposed deadline to get stuff done. They'd just be losing a good chunk of writing each day.

I'm not observing the residents very closely, but I tentatively roll to disbelieve that most of the residents who are publishing last-minute are making full use of the day to write.  My guess is that having e.g. a 10 pm deadline wouldn't reduce "active writing time" by anything like 2 hours for most residents; they would simply "get down to business" earlier in the day.  Someone mentioned that this would substantially reduce the amount of time that residents have to integrate feedback from the feedback circles, which happen right before dinner.  That seems true and somewhat difficult to avoid given the current structure.  I still think that forcing the last-minute writing to happen two hours earlier has a lot of benefits: residents are less tired when they're doing their last minute writing & editing, and they have more time to socialize, unwind, and spend some time doing less "pressured" research/writing/ideating/etc.

It can vary enormously based on risk factors, choice of car, and quantity of coverage, but that does still sound extremely high to me.  I think even if you're a 25-yo male with pretty generous coverage above minimum liability, you probably won't be paying more than ~$300/mo unless you have recent accidents on your record.  Gas costs obviously scale ~linearly with miles driven, but even if your daily commute is a 40 mile round-trip, that's still only like $200/mo.  (There are people with longer commutes than that, but not ones that you can easily substitute for with an e-bike; even 20 miles each way seems like a stretch.)

This inspired me experiment with a "loyal Vizier"-themed system prompt.  Not amazing, but maybe there's something there.

I expect this has most of the costs of keeping them running full-time with few of the other benefits.