I don’t want to post much about the virus. Maybe once a month, taking a more long-term perspective. Take these predictions not as “I believe these are highly probable” but instead as “I find these less improbable than others are currently seeing them.”

1. We will find that regional differences in the impact of the virus depend very little on differences in government interventions. We will down-rate the importance of lockdowns or track-and-trace. Instead, we will up-rate genetic differences and lifestyle differences that affect the immune system in general (take this WSJ essay as a portent). The significance of vitamin D will receive more attention. In addition, we may find that someone’s previous exposure to other viruses affects the immune response to this virus, so that the history of other viruses in a population matters. Sunlight and/or temperature may prove to be important factors affecting the severity of the virus. Finally, we may find that some of the regional variation is due to different mixes of virus strains that prevail in different areas.

2. We will quietly give up on a vaccine. Instead, the focus will shift toward general enhancement of our immune systems. Also, there will be strong social shaming of people who fail to self-isolate when they have fever or other symptoms of illness. The common cold will be as unwelcome in public as leprosy or measles.

3. In years to come, tourism will be highest in the summer months of the country visited. The conventional wisdom will be that you visit Brazil only in January-February, and you visit Italy only in July-August. Even if this virus is no longer salient, people will carry with them a generic perception that you incur health risk if you visit a place during the “unsafe season.”

4. Ventilators will be mothballed. Instead, the treatment of choice for severe cases of the virus will be antiviral cocktails.

5. Student life at colleges this fall will be heavily regulated, to the point where the on-campus experience feels hardly more interesting than staying at home. Among students, deaths from the virus will be much rarer than deaths of despair (suicide will be higher than normal), but where virus deaths do occur the institutions will be forced to close temporarily, and in some instances permanently.

6. In the early fall, the media will be filled with stories, including many false alarms, about a second wave of the virus, particularly in Red states. A realistic picture will emerge only after the election.

7. Florida may do worse in the summer than in the winter, because summer is the season where Floridians spend all day inside.

4/17 to 5/13. As before, bold indicates a post that I think was really on target.

Continue reading →

I went back to look at my posts on the virus crisis, to evaluate them in light of subsequent events. What did I get right before others did, and what did I get wrong?

Some of these posts I consider classics. I put them in bold. Continue reading →

I am demoralized. It occurred to me the movie we’re in.

Fauci plays Big Nurse.

Who plays Randle McMurphy? Trump? Rand Paul? Elon Musk?

Doesn’t matter. The ending is brutal. You don’t want to watch.

I’ll be spending my time outdoors. Not on the computer.

1. Christian Gollier writes,

In this paper, I suppose that herd immunity is the exit door from the pandemic. In the absence of a vaccine, attaining herd immunity requires to expose a fraction of the population to the virus, and to recognize that some people in this targeted population will die. Determining who should be exposed to the virus to attain the herd immunity is a crucial policy issue. . .Some individual characteristics such as the age or the existence of co-morbidity have been shown to have a huge influence on the lethality of the SARS-Cov-2. For example, Ferguson et al. (2020) report that the covid infection-fatality ratio is 0.002% for individuals less than 10 years old, and 9.3% for people aged 80 years and more. Given this 4650-fold difference in mortality risk, it may be desirable to expose less vulnerable people first in the hope of building the herd immunity before relaxing the protection of the more vulnerable people.

Pointer from the diligent John Alcorn. What is your guess as to when the lockdown debate gets shifted toward these terms?

2. Philipp Kircher and others write,

When the young engage in more risky behavior, they reduce the time until herd immunity is reached. The young then take a larger share in the infections needed for herd immunity, which is amplified if the old can shield themselves for short periods by voluntarily engaging in stronger social distancing.

Our calibrated benchmark indicates that the positive externality is indeed present in the absence of a vaccine/cure. This can limit and sometimes negate the effects policies such as temporary shelter-at-home policies. It also indicates that its strength is limited, as it is quickly overpowered through other channels, for example in extensions with scarce hospital beds which the risk-taking young exhaust through their behavior. The interactions by age indicate that it is an important margin to consider, that the effects are not trivial, and that age-specific policies might be warranted.

Another point from JA, and another example of where I think the debate needs to shift. Of course, I should not that this paper uses a simulation model, which I don’t think adds value to the discussion.

3. Daniel Klein and others defend Sweden.

Swedish authorities have not officially declared a goal of reaching herd immunity, which most scientists believe is achieved when more than 60 percent of the population has had the virus. But augmenting immunity is no doubt part of the government’s broader strategy—or at least a likely consequence of keeping schools, restaurants, and most businesses open. Anders Tegnell, the chief epidemiologist at Sweden’s Public Health Agency, has projected that the city of Stockholm could reach herd immunity as early as this month. Based on updated behavioral assumptions (social-distancing norms are changing how Swedes behave), the Stockholm University mathematician Tom Britton has calculated that 40 percent immunity in the capital could be enough to stop the virus’s spread there and that this could happen by mid-June.

We could frame the “opener” vs. “closer” debate this way: openers wish to achieve herd immunity sooner rather than later, while closers wish to achieve it later rather than sooner.

Herd immunity is costly to achieve, in that some people will get sick and die in the process. Closers believe that we should not be trying to hasten to get to herd immunity, presumably because there is an alternative endgame that can be achieved within a reasonable time frame. As one commenter put it,

Which strategy we should pursue depends upon our wild-assed guess as to whether a vaccine or significantly better treatment will appear before civilization ends in economic ruin.

When it comes to virus policy, to whom should we assign status and credibility? I propose that we severely downgrade the status of anyone who speaks in terms of R, or R0. That concept is not helpful. A society could have R well below the “magic number” of 1 and still have a lot of elderly people dying from the virus. A society could have an R above 1 while insulating its elderly and thus having a low death rate.

I keep coming back to the Avalon Hill metaphor, in which what matters is the attack factor and the defense factor. The attack factor is the amount of virus particles that you get hit with. You get hit with more when you spend several minutes in a closed environment with someone who is expelling a lot of virus, especially by coughing or sneezing or singing or yelling. The defense factor is the strength of your immune system, which depends mostly on your age.

I want to focus here on the defense factor. If we had a vaccine, that could give everyone a strong defense factor. To the extent that people who have had the virus are immune, then they have strong defense factors. Young people have strong defense factors. People over 70 presumably have weak defense factors. People with heart conditions or compromised immune systems have weak defense factors.

Is there a rigorous way to evaluate my defense factor? That is something I would like to see researchers working on. If I knew for sure that I have a strong defense factor, then I could be a lot more relaxed about resuming some of my favorite activities.

Although the defense factor is likely to fall on a continuum, for simplicity let us say that there are people of type H and type L, for high defense factors and low defense factors, respectively. I can imagine linking people’s behavior to their defense factors and also to the defense factors of people with whom they must interact.

–If you are type L, then you want to avoid getting the virus. This means only being in places where you can be sure that no one has the virus. If you must be around people who may have the virus (say, you are a health care worker), then you have to follow extreme safety protocols involving personal protective equipment and sanitizing afterward.

–If you are type H and you do not have to interact with people who are type L, then you can interact with whomever you want. Your only responsibility is to try to avoid inflicting a high attack factor on someone. If you do not have antibodies, then you may have the virus, so that you should wear a mask while indoors around people with whom you don’t live. If you have antibodies, then you are harmless to others, even without a mask.

–If you are type H and you have to interact with people who are type L, then you have to be certain that you do not have the virus. You are good to go if you have antibodies. Or if you have been strictly self-quarantining for two weeks. Or if you have reliably tested negative for the virus.

This approach does not try to drive R to any particular value. If R is high among type H people, that could be a good thing.