This is a thread to list important insights and key open questions about the coronavirus and the coronavirus response. The inspiration for this thread is Eliezer's post below.
I'd like this thread to be a source of claims and ideas that are self-contained and well-explained. This is not a thread to drop one-liners that assume I've been following your particular news feed or know what's happening in your country or that I've read a bunch of studies on (say) viral load. There's a place for such high-context discussion, and it is not this thread.
Please include in your answers either a claim or an open question, along with an explanation or an explicit model under which it makes sense. I will be moving answers to the comments if they don't meet my subjective quality bar for justification – see the last justified answers thread for examples of what quality answers look like.
The purpose of giving models and data is to allow other people to build on your answer. Everyone can make arbitrary claims, but models and evidence allow for verification and dialogue.
The more concrete the explanation the better. Speculation is fine, uncertain models are fine; sources, explicit models and numbers for variables that other people can play with based on their own beliefs are excellent.
This thread is inspired by a post by Eliezer Yudkowsky which I'll reproduce below, in which Eliezer lists eight answers that this sort of post would come up with.
These are not justified to the standard of the thread, so you (you!) can get some easy karma by leaving an answer that justifies one of these with the sources/data/explanation needed to argue for it. It includes much of the discussion elsewhere on LW (e.g. by Wei Dai, Zvi, Robin, and others), so it shouldn't be hard to find the prior discussion.
Eliezer's post (link):
What do we early-warning cognoscenti now know about Covid-19 that others haven't currently figured out? What's the TOC of that blog post? @WilliamAEden @robinhanson
My stab at a TOC:
1: The Dose Hypothesis - the theory that C19 fatalities vary by how high the initial dose, and possibly how it's administered.
1a: So: Human trials of variolation are hugely urgent.
1b: So: Getting C19 from a roommate might be much worse than getting it on public transportation.
2: Challenge trials of vaccines save net lives.
3: Ventilators no longer look as important because they only save 15% of the patients on them.
4: There's huge apparent variation in CFR by country, and explaining this, or explaining it away, seems kinda important.
4a: CFRs may be underestimated by up to 3-fold, based on looking at excess death rates year-over-year.
4b: CFRs may be overestimated because of too little testing.
5: There was a huge EMH failure w/r/t C19, and it hasn't been explained away AFAIK.
6: Most of the economic damage from a real shock like this one is still due to the secondary demand shock, which can be prevented by decisive central bank action.
6a: We know the Fed isn't currently doing enough here because inflation expectations are dropping, showing the AD shock exceeds the AS shock.
6b: Stock prices take into account the next 15+ years of earnings. The real C19 shock only damages the next 2 years of earnings. A financial recession would damage many more years. Stock prices mainly reflect central bank policy, not C19.
7: Face masks do work, though others seem to have mostly figured this out.
8: The mainstream media's words on C19 may be best interpreted as not intended to mean things; like the way that MSNBC's talk about Bloomberg being able to give each American over $1,000,000 can't have had a concrete model of reality behind it.
Any items I'm missing here?
Claim: The true infection-to-fatality ratio is definitely about 0.5% to 1%, and most probably around 0.7%, with significant long term morbidity in at least several percent of survivors. Notions that this disease is already widespread or that it has flulike mortality and morbidity or most people are asymptomatic are definitively disproven.
This has been independently estimated in this range before, based on normalizing data from the Diamond Princess and areas where testing was thorough
https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30243-7/fulltext
https://www.medrxiv.org/content/10.1101/2020.03.05.20031773v2
There are a few robust new pieces of data supporting this now.
1 - Blanket RNA testing in Austria.
https://www.theguardian.com/world/2020/apr/10/less-than-1-of-austria-infected-with-coronavirus-new-study-shows
Given a 0.3% current acute infection rate and some epidemiological modeling they estimate 1% of their total population has been infected at some point, with a death rate of 0.77%. Maybe a few false negative PCRs, which would lower that number.
2 - Two serology surveys have now happened in Europe. One was in a hard-hit town in Germany, and one was in a hard-hit town in Italy at the epicenter of its outbreak. In both places, they got approximately a 15% seropositive rate. In Germany, we only have information on deaths with positive test results and it comes to 0.35%. In Italy, total excess deaths over this time last year are about 2.5x the confirmed positive deaths and account for 0.1% of the population, giving an infection fatality rate of 0.7%. It is easy to imagine that some deaths did not get positive tests in Germany which along with a less-old population could make up for the difference.
3 - New test data coming out of NYC.
https://www.nejm.org/doi/full/10.1056/NEJMc2009316
Hardly an unbiased sample, but of 200+ pregnant women coming into a hospital to give birth that were blanket-RNA-tested, 15.3% tested positive.
Of this set of positive tests, only 12% of them were symptomatic on admission, and a further 10% developed symptoms over the course of their 2-day-long stays bringing it to a total of 22% symptomatic upon discharge or transfer. Presumably already-symptomatic very-pregnant women were more likely to be in the hospital already.
Doing a little armchair epidemiology. Let's assume that half of the deaths of currently infected people have happened, due to the lockdown extending the doubling time from three days to more than a week. We get:
~8000 deaths * 2 / (15.3% of 8 million) = 1.3% infection to mortality rate.
If we assume that there were more symptomatic women who didn't show up to normal birthing due to going to the hospital for COVID symptoms, or that there is a good stock of people who have recovered in the city, we get a lower death rate. If 20% of the total population was ever infected, we get a 1% mortality rate. 30% ever infected, 0.67%.
EDIT: 4 - Apparently there is a similar maternity ward study in Stockholm, revealing 7% positive. There have been 550 deaths there, and a population of 2.3 million. If we again assume half of current cases that will die has died, we get a infection to fatality ratio of 0.68% without further corrections. I suspect they haven't crushed the doubling time as much as NYC, raising this number, which then can get lowered down again as I did above.
EDIT: 5, a meta analysis of a whole bunch of research comes to exactly my original conclusion, 0.5% to 1% with a central tendency of 0.8%.
https://t.co/51b3bJYg3e?amp=1
UPDATE as of 4/28/2019.
Others coming to this exact same distribution more rigorously.
https://t.co/51b3bJYg3e?amp=1
Compiling rigorous data, the compatible range is circa 0.5% to 1% with a central tendency of 0.8%.