Friday, December 10, 2021

Vaccination: Two Arguments

Vaccination against Covid reduces both the chance of catching Covid and the severity. Both provide arguments for vaccination, but different arguments. The first has so far been the main argument for pressuring people to get vaccinated, to reduce the infection rate and, hopefully, get us to herd immunity.

Unfortunately, protection against infections has turned out to be weaker than expected and diminishes substantially over time, which may help explain* why widespread vaccination has not led to a pattern of lower infection rates. Part of the reason may be behavioral. Vaccinated individuals are at much less risk of death or hospitalization, which may, probably does, lead them to be less careful to avoid contagion. And, because their cases are more likely to be asymptomatic, they are less likely to know they are contagious and take precautions against infecting others.

The most recent U.S. data on the new Omicron variety of Covid suggests that vaccination may provide no protection against it at all. Of cases identified so far, 79% were in fully vaccinated individuals, 21% in individuals who had also received booster shots more than two weeks before. For the U.S. population as a whole, about 60% are fully vaccinated, 15% have had booster shots. Judging by those numbers, vaccinated people, with or without booster shots, are more likely to get the disease, not less. The numbers are small enough so that could be chance variation and a more careful analysis should allow for different probabilities of a detected infection at different ages — children are both less likely to be vaccinated and less likely to get an infection serious enough to be detected than adults. But the numbers so far still suggest that vaccination provides little if any protection against catching the new variant. If so, the main argument for vaccine mandates is becoming increasingly irrelevant as Omicron spreads. 

Whether or not vaccination provides protection against getting the virus, it provides substantial protection against hospitalization or death. While protection against infection seems to be down to something like 50% after a few months, protection against severe cases remains high; that is the main reason that death rates have been substantially lower, relative to infection rates, than before. That is a good reason for me to get vaccinated and get a booster, and I have. It is a much weaker reason for me to insist on other people getting vaccinated.

A weaker reason, but still a reason. Under our present medical system, part of the cost of hospitalization from Covid is born by the patient or his insurance company but not all. Especially if hospitalization for Covid gets high enough to crowd hospitals, as it has in a few parts of the U.S. but not yet most, my hospitalization imposes a significant cost on other people. As people become increasingly skeptical of claims that herd immunity is reachable if we just vaccinate enough people, the argument for vaccine mandates shifts to keeping the hospitals from filling up.

That is an argument for requiring the vulnerable elderly to be vaccinated — but most of them already are. It is a very weak argument for universal vaccination, especially  for requiring children to get vaccinated. According to CDC figures, ages 0-17 have so far accounted for about one percent of all Covid associated hospitalizations. Protection against infection is an argument for requiring children to be vaccinated, since they can pass infection on to their much more vulnerable elders. Protection against hospitalization is not.

*The other explanation being the spread of the more contagious Delta variant.

A commenter on the version of this post on FaceBook points at a study that found no relation between level of vaccination and infection rates across both countries and US counties as of seven days before September 3rd, which suggests that the behavioral effect of vaccination may be strong enough to balance the vaccine's protection, at least that long after vaccination.

7 Comments:

At 4:33 PM, December 10, 2021, Anonymous Arqiduka said...

That second argument- weak as it may be - is the argument for slavery.

If a group can be made to take a vaccine due to high treatment costs borne by others, what about smokers, fast food lovers or those who skip gym? Indeed, what is stopping any regime from having people (paraphrasing from memory) board themselves up, eat but asparagus and live the long life, if life that may be called?

At some point a society is called to draw a bright red line over externalities, and ingore those that fall on the wrong side if it, else freedom as a concept is meaningless.

 
At 7:52 PM, December 10, 2021, Blogger David Friedman said...

I agree, but the point of the post is the difference between the two arguments and the fact that one of them may be becoming irrelevant. I don't only post for people who agree with me.

 
At 10:38 AM, December 11, 2021, Blogger Michael Wolf said...

One of the (many) reasons why things like this must be kept to personal choice is that, else, we are implicitly hubristically asserting that we know all there is to know about a very new thing and its effects. With the disproportionally high infections of Omicron in the vaccinated, we *may* be seeing issues related to original antigenic sin: https://www.sciencedirect.com/science/article/pii/S2772613421000068

It is too early to know for sure either way, but the fact that we don't know and can't know - among many other things we don't yet know - are principled arguments against mandatory vaccinations, at the very least for a long time until much, much more time has passed and data collected. Considering the reasons to believe AEs have been underreported - the myocarditis risks of 1/1300 for young men, for example, that we had no idea about after the EUA trial data (https://twitter.com/rfsquared/status/1469415659813621761) - it is really irresponsible to make any of this mandatory. I would argue ever, but even if you would accept mandates at some point, we are not nearly at that point yet for clear and compelling obvious reasons.

 
At 9:21 AM, December 12, 2021, Blogger Modern Mugwump said...

@Arqiduka Or, we could make people pay for the externalities they impose on others. Strange and wild idea, I guess.

 
At 12:25 PM, December 12, 2021, Anonymous A Country Farmer said...

> Protection against infection is an argument for requiring children to be vaccinated, since they can pass infection on to their much more vulnerable elders.

Debatable:

1. Munro APS, Faust SN. Children are not COVID19 super spreaders: time to go back to school. Arch Dis Child 2020;105(7):618-619. doi: 10.1136/archdischild-2020-319474. Erratum in: Arch Dis Child 2021;106(2):e9.

2. Ludvigsson JF. Children are unlikely to be the main drivers of the COVID-19 pandemic—a systematic review. Acta Paediatr 2020;109(8):1525-1530. doi: 10.1111/apa.15371.

 
At 8:39 PM, December 12, 2021, Anonymous Arqiduka said...

Not strange at all, just functionally the same as slavery - with extra steps, as the line goes.

 
At 9:03 AM, December 13, 2021, Anonymous Anonymous said...

While protection against infection seems to be down to something like 50% after a few months, protection against severe cases remains high; that is the main reason that death rates have been substantially lower, relative to infection rates, than before.

Maybe. Another possibility is that the most vulnerable people already died off during a previous wave, leaving a disproportionate number of people with relatively healthy immune systems.

GregL

 

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