Van Nostrand, Alexander, and Mowshowitz on Long COVID

This is a quick set of excerpts I’m putting together for easy reference.

Elizabeth van Nostrand wrote an Aug. 30 blog post, Long Covid Is Not Necessarily Your Biggest Problem, concluding that “for vaccinated people under 40 with <=1 [comorbidity], the cognitive risks of long covid are lost in the noise of other risks they commonly take”.

She also concludes that

[…] your overall risk of long covid is strongly correlated with the strength of the initial infection. […]

Van Nostrand estimates estimates that the risk of hospitalization for a vaccinated person who catches Delta is:

  • 0.38% for a healthy 30yo man;
  • 0.24% for a healthy 30yo woman;
  • 0.58% for an asthmatic 25yo man;
  • 0.92% for a 40yo obese woman.

And:

[…] My tentative conclusion is that the risks to me of cognitive, mood, or fatigue side effects lasting >12 weeks from long covid are small relative to risks I was already taking, including the risk of similar long term issues from other common infectious diseases. Being hospitalized would create a risk of noticeable side effects, but is very unlikely post-vaccine (although immunity persistence is a major unresolved concern).

I want to emphasize again that ‘small relative to risks you were already taking’ doesn’t necessarily mean ‘too small to worry about’. For comparison, Josh Jacobson did a quick survey of the risks of driving and came to roughly the same conclusion: the risks are very small compared to the overall riskiness of life for people in their 30s. Josh isn’t stupid, so he obviously doesn’t mean ‘car accidents don’t happen’ or ‘car accidents aren’t dangerous when they happen’. What he means is that if you’re 35 with 15 years driving experience and not currently impaired, the marginal returns to improvements are minor.

[…] What this means is not that covid is safe, but that you should think about covid in the context of your overall risk portfolio. Depending on who you are that could include other contagious diseases, driving, drugs-n-alcohol, skydiving, camping, poor diet, insufficient exercise, too much exercise, and breathing outside [during wildfire season]. If you decide your current risk level is too high, or are suddenly realizing you were too risk-tolerant in the past, reducing covid risk in particular might not be the best bang for your buck. Paying for a personal trainer, higher quality food, or a safer car should be on your radar as much as reducing social contact, although for all I know that will end up being the best choice for you personally.

In Long COVID: Much More Than You Wanted To Know, Scott Alexander expresses stronger worries about long COVID (albeit with a broader definition of ‘long COVID’ that includes very mild symptoms like ‘reduced sense of smell’):

The prevalence of Long COVID after a mild non-hospital-level case is probably somewhere around 20%, but some of this is pretty mild.

[…]

Vaccination probably doesn’t change the per-symptomatic-case risk of Long COVID much

Alexander’s Fermi estimate:

About 25% of people who get COVID report long COVID symptoms. About half of those go away after a few months, so 12.5% get persistent symptoms. Suppose that half of those cases (totally made-up number) are very mild and not worth worrying about. Then 6.25% of people who get COVID would have serious long-lasting Long COVID symptoms.

[…] I’m going to round all of this off to about 1% – 10% per year of getting a breakthrough COVID case (though obviously this could change if the national picture got better or worse). Combined with the 0.4% to 6.25% risk of getting terrible long COVID conditional on getting COVID, that’s between a 1/150 – 1/25,000 chance of terrible long COVID per year.

[…] I find the 1/150 risk pretty scary and the 1/25,000 risk not scary at all, so, darn, I guess there’s not yet enough data to have a strong sense of how concerned I should be.

Zvi Mowshowitz comments on Alexander’s post in Covid 9/2: Long Covid Analysis:

[…] What I’m confused by is how he uses the data he reports in this section to end up at 20%, since he quotes studies where (Long Covid percent in Covid group minus Long Covid percent in control group) is respectively at most 28%, 12%, 17%, 13% and 13%, two of which lack a control group. If we naively average that we get 17% minus a few percent for the missing control groups, so maybe 15%. Scott seems to be buying that ‘any symptom at all’ is a reasonable standard here, and that asking ‘did you have Long Covid?’ is ripe with false negatives.

[…] I think we can safely throw out the upper part of [Scott’s] range, as I think a 10% chance of breakthrough symptomatic Covid within a year isn’t reasonable if you do a little math, and it’s starting at 25% which seems higher than the studies referenced above would suggest, so I think the range here would be more like 1 in 1,000 to 1 in 25,000.

[…] Long Covid seems legitimate, and worth a nonzero amount of effort to minimize, but my model says it is mixing a lot of things together, is largely typical of what happens after being sick, is protected against by vaccines similarly to how they protect against symptomatic disease, and in many studies they go on a fishing expedition for symptoms then attribute everything that happens chronologically after Covid to Covid.

Van Nostrand summarizes her disagreements with Alexander in Alternate Views on Long Covid:

– […] I think his studies are too small and sample-biased to be meaningful.

– He thinks my studies (especially Taquet) didn’t look at the right sequelae.

– I was only looking at cognition (including mood disorders), whereas he looked at everything.

Scott also didn’t do age-specific estimates, although I’m that’s not a crux because I expect other post-infection syndromes to worsen with age as well.

I intended to include fatigue in my analysis of cognitive symptoms but in practice the studies I weighted most highly didn’t include them. Scott’s studies, which he admits are less rigorous although we differ on how much, did include them. Why the hell aren’t the large, EHR-based studies with control groups looking at fatigue? […]