ok dumb question what is the best current research on long-term effects of COVID?
I haven’t really been following COVID discourse much for several months but like … we have enough data by now to know like what percentage of people by age group, etc are experiencing various symptoms six months later, right?
googling has so far failed to turn up anything concrete
ok, reading through this article:
- a study of people who were hospitalized in Italy showed that 87% had at least one symptom 2 months later. this is just people who were hospitalized though, which accounts for 15% of diagnosed cases, and a lot lower in younger people
- another study in Ireland found half of people having fatigue 10 weeks after being infected, but I think this has similar selection effects (it looks like participants were recruited from people who were attending a post-COVID follow-up appointment?)
- the COVID Symptom Tracker app in the UK found that 2% of people were still experiencing any symptoms after 90 days. that seems pretty different from the above two numbers! I’m not sure how representative of a sample their userbase is, but they do have 4m users which is a lot. I can imagine it being biased toward young people, but at least that tells us that the rate of long COVID is pretty low in young people.
looking back at a spreadsheet I made back in March, my guess was that DALY costs from long-term effects of COVID would be 2x DALY costs from deaths. if the 2% number is real, then I feel like 2x is a reasonable upper bound, and probably significantly too high; either way, seems like much lower than would justify the costs of lockdown.
But see: https://mobile.twitter.com/ahandvanish/status/1313973286364229638. tl;dr the app may be significantly underreporting because it’s clunky & people get tired of reporting symptoms
hm ok, I’m having a hard time confirming this but it sounds like the 2% number isn’t “98% reported that they were symptom free after 3 months” but “2% were still bothering to put their symptoms in an app every day after 3 months,” which seems pretty different :/
this spreadsheet (from the twitter you linked) has what seems like a reasonable compilation of studies on long-term COVID symptoms and the studies seem … mostly not that helpful?
out of the 21 studies listed, only 6 seem to be on potentially representative samples (the rest are on hospitalized patients, or recruited from support groups, etc). out of those, two are < 1 month, and one was a sample of fifteen people. looking at the remaining ones:
- one was a news article in French citing a researcher in Switzerland who said that one in three patients was still having symptoms two months later. didn’t get any more details than that
- one was a study from Wuhan of 153 patients, finding that 11% still had symptoms after 3 months. seems ok though not very big, not really controlled, and they warn there might be bias in who responded to their survey
- the most promising one looks like a preprint posted a few days ago (!) it looks at 233 people in the US who tested positive for COVID, comparing to a large group of the general population. it finds that 24% of COVID patients have at least one symptom after 90 days, compared to 6% of the control group reporting one of the same symptoms lasting for 90 days. there were only a few symptoms that were significantly more prevalent in the COVID group than the control group (loss of smell and taste, headache, and rapid heartbeat) though probably the sample size isn’t big enough to say that much about individual symptoms
so yeah, idk. this definitely updates me higher on the number of people who still have symptoms after 3 months: seems like 20% is a better estimate than 2%. mostly though, the state of the evidence seems surprisingly bad given that COVID’s been around for a while.