General update, April 23

1. The mayor of Las Vegas does not want to order Casinos closed.

I think they can do whatever they want. Anti-fragile Arnold is not going. Las Vegas was never his cup of tea. But if Risky Randy wants to go, that does not affect Arnold.

A lot of people think of government as a parent. It should tell them what to do and what not to do, and it should give them money when they need it. I think that smart phones have really increased the proportion of the public that views the government in those terms, because politicians and family members both appear on the same screen.

And in a Twitter world, people don’t take time to reflect. In Kahneman’s terms, their emotional System 1 is very pronounced and their reflective System 2 doesn’t get activated.

2. The Sacramento Bee reports,

Following Monday’s protest at the state Capitol where demonstrators defied Gov. Gavin Newsom’s orders banning large gatherings, the California Highway Patrol says it will no longer issue permits for events at any state properties, including the Capitol.

You knew this was coming. If we still had an American Civil Liberties Union, they would fight for freedom of assembly. But now I wonder if they are on the other side.

3. Nicolas Banholzer and others write,

The closure of venues is associated with a reduction in the number of new cases by 33 % (95% credible interval [CrI] 16–47 %). The reduction is lower for work bans on non-essential business activities (28 %; 95% CrI 10–42 %) and border closures (26 %; 95% CrI 13–37 %). School closures yield a reduction of only 11 % (95% CrI 0–27 %) and its relative impact is one of the lowest among the various policy measures considered in this analysis

They also look at the marginal effect of a lockdown, defined as only letting people leave home for essential purposes. This they find is even lower than the effect of school closings. Pointer from John Alcorn.

4. John Kay writes,

Despite the passage of four months since the first known human cases of COVID-19, our public-health officials remain committed to policies that reflect no clear understanding as to whether it is one-off ballistic droplet payloads or clouds of fine aerosols that pose the greatest risk—or even how these two modes compare to the possibility of indirect infection through contaminated surfaces (known as “fomites”).

Gaining such an understanding is absolutely critical to the task of tailoring emerging public-health measures and workplace policies, because the process of policy optimization depends entirely on which mechanism (if any) is dominant:

1. If large droplets are found to be a dominant mode of transmission, then the expanded use of masks and social distancing is critical, because the threat will be understood as emerging from the ballistic droplet flight connected to sneezing, coughing, and laboured breathing. We would also be urged to speak softly, avoid “coughing, blowing and sneezing,” or exhibiting any kind of agitated respiratory state in public, and angle their mouths downward when speaking.

2. If lingering clouds of tiny aerosol droplets are found to be a dominant mode of transmission, on the other hand, then the focus on sneeze ballistics and the precise geometric delineation of social distancing protocols become somewhat less important—since particles that remain indefinitely suspended in an airborne state can travel over large distances through the normal processes of natural convection and gas diffusion. In this case, we would need to prioritize the use of outdoor spaces (where aerosols are more quickly swept away) and improve the ventilation of indoor spaces.

3. If contaminated surfaces are found to be a dominant mode of transmission, then we would need to continue, and even expand, our current practice of fastidiously washing hands following contact with store-bought items and other outside surfaces; as well as wiping down delivered items with bleach solution or other disinfectants.

Pointer from Russ Roberts, via email. This is a great, great article. Kay takes pains to point out that he is not an epidemiologist or a virologist. But I would give him the highest praise. He is an epistemologist. Like Scott Alexander and like Russ, Kay focuses on what we might know and how we might know it.

Kay looked for evidence in the reports of “superspreader events,” and the evidence seems to come closer to (1) above. This is consistent with the beliefs that I have.

12 thoughts on “General update, April 23

  1. 3) With respect to surfaces being a major mode of transmission, I’ve seen video of foggers being used to decontaminate in several east Asian countries. My assumption is that these are for surface decontamination. I’m not sure exactly what they’re spraying.

    Why haven’t I seen these foggers being used in western countries? Are they just for show?

  2. Arnold, I suggest reading this long post published today

    http://blueberrytown.com/index.php/2020/04/23/tip-toeing-in-a-dark-house/

    It complements and expands well what you have been arguing.

    In a previous post, the anonymous editor of the blog argues that

    “Ultimately, we will know three things in each applicable jurisdiction (itself a hot topic, of which a bit more below): (1) excess deaths (whether from the virus or the stress of the economy and confinement or from the local collapse of the healthcare system) over the baseline experience, (2) excess morbidity and mental health problems, and (3) the decline in the jurisdiction’s GDP per capita against the baseline. Those three things in a given country or state will be the indicators of success or failure.”
    http://blueberrytown.com/index.php/2020/04/17/covid-quandry-how-do-we-know-which-policies-have-been-or-will-be-successful/

    It’s time to discuss again the indicators of success and failure.

    Note: Like you, I don’t like GDP as a measure of an economy’s output. Given that GDP will be used, it’s important to remember that originally GDP intended to measure the output of market activities valued at market prices, but as discussed by D. Coyle in his little book on GDP, it ended up including also government output valued at whatever cost it was accounted. In the next few months when GDP data are published, we are going to see a substantial reduction in the output of market activities but not in the government’s output although many government employees have not worked (strictly, the payments to non-working employees should be counted as a transfer payment).

  3. 4. It is interesting how different events are interpreted. The Los Angeles choir practice event has been seen as evidence of microdroplet transmission since no one was sneezing or coughing and therefore not producing large droplets: https://www.latimes.com/world-nation/story/2020-03-29/coronavirus-choir-outbreak
    Does singing produce both large and small droplets? What non-sneezing, non-coughing activities produce large droplets? How much “say it, don’t spray it” actually goes on?

    I think the NYC fitness club infections early on contradict the large droplet only theory as well as it was suspected that the heavy breathing associated with exercise was the vector, not sneezing, coughing, singing. As they say, I suspect that the jury is still out.

    • There is a lot of asymptomatic spreading so it can’t be just cough and sneeze blasts.

    • Does singing produce both large and small droplets?

      I once sat in the front row of a Jose Carreras concert (not on my own dime). Should have taken an umbrella.

  4. CDC released an assessment of infection prevalence in homeless shelters, a study period which ended about a week ago.

    These are shelters, so these are indoor homeless vs outdoor homeless, at least, some of the time.

    One San Francisco shelter had two thirds positive, (95/143 – 66%), most asymptomatic. In Atlanta it was only 4%. That’s a massive difference.

    The shelters are all kind of different and did different things, including sending people for tests early or late, and reacting or not after they got a positive case. The Boston shelter is Big (408 residents), San Francisco and Atlanta averages Medium (143, 125) and Seattle averages Small (20-60 each).

    Of shelters where there were at least two positive cases in the 2 weeks prior to testing, residents positive:

    SF: 66% (16% of the staff)
    Boston: 36% (30% of the staff)
    Seattle: 17% (17% of the staff)

    12 small Seattle shelters had 1 case before testing, and averaged only 5% (1% staff)

    The two medium Atlanta shelters had no confirmed cases, averaged 4% exposure (1% staff)

    If you let the virus rip through a nursing home, a lot of those old people are going to die. If you let the virus rip through a big homeless shelter, the vast majority of them won’t even know they had it.

  5. Re: 1, correct. Presumably the mayor is not forcing individuals to go to Las Vegas/take part in activities. She’s merely allowing them to make the choice themselves.

    The fact that she herself wouldn’t necessarily make the choice in the affirmative does not suggest that she shouldn’t be allowed to offer the choice. I can think of other reasons to bar her from offering the choice, but her personal decision to not take the risk shouldn’t suffice.

    I don’t choose to skydive. I think it’s reasonable enough for others to have that option even though I wouldn’t personally go for it.

    I suspect many vilifying her support legalization of other semi-risky activities on the basis that individuals can make their own choices, even when they themselves have calculated the activities as not worth the risk.

  6. We all hope that there is some clear magic bullet (masks, warm weather, avoiding AC/VC, subways, etc).

    There may well be but at present, the clearest conclusions to me seem to be that this thing is extraordinarily multi-factorial, with a significant component of stochastic randomness thrown in.

  7. “if we still had an American Civil Liberties Union, they would fight for freedom of assembly. But now I wonder if they are on the other side.”

    Is that even a serious question lol. The ACLU has long been on the anti-civil liberty side for a while now, at least three decades. That is like asking “Does PPFA actually care about reproductive freedoms, sexually transmitted infection reduction, etc or is it really just an abortion mill furthering its founding eugenics program to eliminate undesirable minorities and poor whites masquerading as a advocacy group”.

    Thank you on #4 though, good read. Thank you to Russ if reading.

  8. Why is the transmission model either aerosols or droplets? Couldn’t it be that sometimes aerosols lead to infection, and sometimes it is large droplets? I would go on the assumption that both have played a material role in transmitting the virus. Like many things, the cost of getting people masks and improving ventilation of indoor workplaces is likely to be relatively cheap compared to an indefinite lockdown.

    • But if the tests are not sufficiently accurate, this may not in fact yield a valid baseline.

Comments are closed.