I would focus on the UK metareview she looked at, since it should better capture the risk of severe brain fog and fatigue. The intelligence study estimated the average drop in IQ by acute symptom severity, but I think there are decreasing marginal returns to IQ, so I’m more worried about a small risk of a big drop (or being unable to even focus on doing an intelligence test, due to brain fog or fatigue), and Taquet et al focused on neuro and psych diagnoses that did not include brain fog or fatigue. Here’s what she had to say based on the metareview:
A UK metareview found the prevalence at 12 weeks of symptoms affecting daily life ranged from 1.2% (average age: 20, minimum 18) to 4.8% (average age: 63). The cohort with average age 31 had a mean prevalence of 2.8%., which is is well within the Lizardman Constant. This is based on self-reports on survey data, which will again exclude asymptomatic cases, so even if you treat it as real, you need to discount it down to 2.8%.
On the other hand, medicine is notoriously bad at measuring persistent, low-level, amorphous-yet-real effects. The Lizardman Constant doesn’t mean prevalences below 4% don’t exist, it means they’re impossible to measure using naive tools.
I think this gives us a fairly reliable upper bound on the risk of severe long COVID cases (“affecting daily life”, or in the study’s wording, “limiting day-to-day function”) for healthy people in the given age groups, and a more reliable upper bound than Matt Bell’s, since
Matt Bell’s started from overall prevalence estimates that don’t depend on severity and then made adjustments for severity based on other studies, and this seems more prone to bias/error, and
the above study is more directly attempting to measure what we care about, and seems unlikely to be biased downwards.
There’s no comparison group here in this metareview, and this is an absolute risk estimate based on self-reported symptom duration, according to NICE’s definition of post-COVID-19 syndrome (PCS), which is supposed to rule out alternative diagnoses at least, but that can still leave room for people misreporting or not knowing that there is an alternative explanation:
Post-covid-19 syndrome—Signs and symptoms that develop during or after an infection consistent with covid-19, present for more than 12 weeks and are not attributable to alternative diagnoses.
This is also pre-vaccine, and pre-Delta (and so, of course, pre-Omicron). It’s also not clear exactly how severe “limiting day-to-day function” is supposed to be, without looking further into it.
Also, by Elizabath (I think her LW post was not updated since some corrections were made).
I would focus on the UK metareview she looked at, since it should better capture the risk of severe brain fog and fatigue. The intelligence study estimated the average drop in IQ by acute symptom severity, but I think there are decreasing marginal returns to IQ, so I’m more worried about a small risk of a big drop (or being unable to even focus on doing an intelligence test, due to brain fog or fatigue), and Taquet et al focused on neuro and psych diagnoses that did not include brain fog or fatigue. Here’s what she had to say based on the metareview:
I think this gives us a fairly reliable upper bound on the risk of severe long COVID cases (“affecting daily life”, or in the study’s wording, “limiting day-to-day function”) for healthy people in the given age groups, and a more reliable upper bound than Matt Bell’s, since
Matt Bell’s started from overall prevalence estimates that don’t depend on severity and then made adjustments for severity based on other studies, and this seems more prone to bias/error, and
the above study is more directly attempting to measure what we care about, and seems unlikely to be biased downwards.
There’s no comparison group here in this metareview, and this is an absolute risk estimate based on self-reported symptom duration, according to NICE’s definition of post-COVID-19 syndrome (PCS), which is supposed to rule out alternative diagnoses at least, but that can still leave room for people misreporting or not knowing that there is an alternative explanation:
This is also pre-vaccine, and pre-Delta (and so, of course, pre-Omicron). It’s also not clear exactly how severe “limiting day-to-day function” is supposed to be, without looking further into it.