is "long covid" mostly a mental disease?
because it looks like "thinking you had covid" produces pretty much all the long term symptoms. having actual covid does not.
surprising basically no one who has actually been paying attention, this french study seems to demonstrate that “long covid” is not, in fact, predominantly caused by covid.
they start with a simple premise:
they then looked at about 27k adults who passed their screen and generated serology data for all of them to seek covid antibodies. before any knew their serology outcome, they were asked about whether they thought they had had covid and then about a battery of long term symptoms.
the results are not kind to the case for long covid being a mostly real medical syndrome. it’s overwhelmingly clear from this data that “belief about having had covid” absolutely swamps whether or not you actually had covid.
this table is, frankly, absolutely savage. (it’s just sufficiently technical that people are not getting what a brutal take down it is.) let’s look:
you really want to look at model 3, the most compete set of regressions here that measures both variables (covid status, belief about covid status) and controls for exogenous variables like age, sex, income, education, etc)
it’s showing you relative risk ratios.
the headline number should be broadly distrusted if the confidence interval (parenthetical after it) passes through 1.
that implies you really would struggle to tell it apart from being random and that the effect could have been positive or negative.
note that every single outcome except for ansomia (loss of taste or smell) passes across one when measuring serology as a predictive variable.
apart from losing smell/taste (a very specific and noticeable symptom with few other causes), whether you had that symptom is not meaningfully predicted by whether you actually had covid.
now look at “belief that you had covid.”
the values are much higher and most do NOT pass through 1. in most cases, it’s 2-5 times as impactful and can be separated from chance.
this is the very definition of either psychosomatic disease or exogenous conditions being ascribed to the wrong causes.
at any given time, lots of people have general medical conditions or idiopathic origin. there’s a natural tendency to want to attribute them to whatever is going around/whatever everyone is talking about. you get these sorts of “trash can” diagnoses of exclusion and arbitrary attribution. in 2018, it was “chronic fatigue syndrome.” now it’s long covid, because the people stayed the same, but the zeitgeist changed.
and long covid looks like that.
any disease from flu to malaria can leave lasting effects. it happens all the time though at low incidence. but separating it from belief is always tricky and so it tends to get over-ascribed.
this was a clever study to separate those notoriously blended effects. (frankly, a lot of studies could benefit from a belief arm like this)
you can see here that not having had covid but thinking you did led to VASTLY more reports of “long covid” than having had covid and NOT thinking you had.
it’s true in every single category.
(this may have some severity confounds around those who got covid, but even so, you’re still seeing that imaginary covid has far greater lasting effects than mild covid in such a case. i’m not sure about whether the powering here is sufficient to draw statistically significant inference from comparing belief with - to belief with + serology. the gap is awfully small for n of 461 vs 453 and seems to invert based on symptom)
placebo effect is incredibly real. it’s WHY we do double blind studies.
clearly, belief mattered a lot here, far more than disease status. it’s difficult to even really identify a signal of real clinical long covid from this data.
but imagined long covid stands out like an air horn in a library.
worth keeping in mind as this bugbear gets repeatedly pulled out as a pretext for vaccination, masks, and distancing.
i have seen no convincing evidence that long covid is any more an issue than long flu. for kids, it’s almost certainly far less.
this is mostly on of those monsters that’s only under the bed if you believe it is.