Estimates of the prevalence of long Covid – where symptoms persist for more than four or more than 12 weeks after infection, depending on the exact definition – vary dramatically.
Before getting to the estimates, what kind of symptoms are we talking about? All of the following have been reported: abdominal pain; cough; diarrhoea; fatigue; fever; headache; loss of taste; loss of smell; myalgia; nausea or vomiting; shortness of breath; and sore throat.
The ONS has documented that almost 14% of people who test positive for COVID-19 continue to report at least one symptom 12 weeks later. This estimate is based on data from the Coronavirus Infection Survey (CIS) – a large, random sample of UK residents living in private households. Here’s the ONS’s chart:
The control participants comprise individuals who took part in the CIS but were unlikely to have been infected. Note that only 2% reported at least one symptom on the relevant date. This seems to suggest that fully 12% of people who test positive for COVID-19 go on to experience long Covid (over and above the background rate).
However, while the CIS is a high-quality sample, the 12% figure isn’t necessarily correct. That’s because the symptoms are self-reported, and we don’t have any information on severity.
Due to the amount of media attention long Covid has received, CIS participants who tested positive might have been inclined to exaggerate their symptoms – to report things they normally wouldn’t have done. In other words, some of their symptoms might be more psychosomatic than physical.
By way of comparison, a study published in Nature Medicine in March of this year gave the percentage of people still reporting symptoms after 12 weeks as only 2.3%. This estimate is based on data from the Covid Symptom Study app, which asks participants to input their symptoms at regular intervals.
In a recent unpublished study, researchers analysed data from several longitudinal surveys, and found that the percentage of people still reporting symptoms after 12 weeks ranged from 7.8% to 17%, depending on the mean age of the sample (with older samples yielding higher estimates).
However, the authors of that study also estimated the prevalence of long Covid in the general population. They examined 1.2 million NHS patients’ electronic health records, and found that only 3,327 had been assigned a long Covid code, which amounts to just 0.3%. This suggests, the authors note, that “only a minority of people with long Covid seek care”.
In another recent study, researchers analysed an even larger sample of patients’ health records (comprising 58 million people) and found that only 23,273 – or 0.04% – had received a long Covid code. The outcome in this study was measured between February of 2020 and April of 2021.
In March of 2021, the ONS estimated the prevalence of long COVID as 1.1 million, or 1.7% of the UK population. This is is 41 times higher than 0.04%. According to the authors, the latter may reflect “under-coding, sub-optimal communication of clinical terms, under-diagnosis, a true low prevalence of long Covid diagnosed by clinicians, or a combination of factors”.
Given the possibility that some people’s long Covid symptoms are psychosomatic, the best way to estimate the condition’s prevalence is to ask people about their symptoms without revealing whether they’ve ever been infected. The true prevalence is then equal to the difference in frequency of symptoms between those who have and haven’t had the virus.
As Will Jones noted back in May, an unpublished German study used this method and found “no statistical difference” between those who were seropositive and those who were seronegative. One caveat is that their sample comprised students aged 14–17, so the results may not be generalisable to the adult population.
Interestingly, a new study based on Swiss data has reached a similar result: 4% of those who were seropositive reported symptoms after 12 weeks, compared to 2% of those who were seronegative – a difference of only 2 percentage points. However, the sample comprised students from primary and secondary school, so the same caveat applies as before.
Overall then, estimates for the prevalence of long Covid range from 0.04% to 1.7% of the population. And estimates of the chance of reporting symptoms after 12 weeks range from less than 1% to almost 12%. Given all the available evidence, I would suggest that those toward the low end are more plausible – especially if we’re talking about something of clinical significance.
This post has been updated.
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Thanks; good article.
Twas ever thus, and again we are powerless to do anything. They falsely blacken the names of anyone who opposes their view, call them deniers (of what), or accuse them of being in the pay of vested interests (have you got to be one to know one?) like big oil or the Russians/Chinese.
A pox on the lot of them, except they would exploit the pox, lock us all down and try to feed us untested drugs to destroy our spirit.
Perhaps “incestuous,” is a bit harsh. Just friends helping each other out.
At our expense.
Lovely people.
“A bit harsh”?? There is nothing too harsh for the charlatans. The friends “helping each other out” are sending millions in the wealthy west into energy poverty and causing those in the third world to stay dying young of preventable diseases and back breaking labour because they are denied fossil fuels and fobbed off with phony renewables to “save the planet”.
I was of course extracting the urine. My dry, northern humour clearly doesn’t travel well.
AHH Yes——————–I have tried my dour Scots humour a few times and it hasn’t worked. People got the wrong idea and thought I was being serious and then I had to go and explain. It’s never good when you have to explain your jokes. —But actually I kind of knew you were taking the piss. I just never let a good opportunity for a rant about the climate hoax to pass.
I think the term “renewables” is deliberately misleading. Solar panels and turbine blades are not renewable or recyclable and have to be replaced. We should have energy definitions around the common denominator of “fuels”, viz:
fossil fuels
nuclear fuels
biomass fuels
imported fuels &
*weather fuels*
That’s much more honest!
They mean the fuel itself is “renewable”, but ofcourse there is nothing “honest” when it comes to anything remotely connected to climate change dogma. The whole thing is a pseudo scientific fraud with all manner of people and businesses feeding at the subsidy trough filled with taxpayers misspent money.
Intermittent (weather) and non intermittent (everything else). Non intermittent could usefully be subdivided into “easily ramped up” (e.g. gas) which is good for meeting peak demand and not easily ramped up (e.g. nuclear, possibly coal) more suitable for base load. You could also usefully subdivide between sources that are under our control (we have the fuel and the technology) and sources where we rely on other countries.
We get roughly 10% of actual generated electricity from abroad (mainly France and Norway)
To some extent it’s a question of time. The only one on the list that is not renewable is nuclear; the rest are produced by plants in the longer term. After all, they claim that “biomass” such as wood fuel for Drax is kind of renewable in the medium term, whereas so-called “fossil fuels” are longer term storage mechanisms.
Is Uranium not naturally occurring / created in the ground around the world? Highly reprocessable fuel as well. Take your general point though. Biomass through growing weed trees etc could be sustainable,
trouble is you need a lot of land
They didn’t get it wrong. The figures were changed, or to use a previously used term, sexed up to support a pre determined policy.
The system doesn’t work how it’s supposed to work or how people are made to believe it works.
We.live in a completely corrupt system.
I challenge anyone to show me otherwise.
Yet how often do we hear that anyone who questions Climate change orthodoxy or the green technologies that are supposedly going to fix all of that (whatever all of that is supposed to be) must be “in the pay of big oil”. They are “stooges for the fossil fuel companies”. The implication being that fossil fuels are the devil incarnate despite providing 85% of the worlds energy and bringing billions out of a miserable life of abject poverty, and renewables are all sweetness and light despite providing about 1% and forcing poorer people in developed countries into energy poverty and adversely affecting economies. Those champions of these niche technologies then insist that poor people living on a dollar a day in the third world should not use their fossil fuels to “fight climate change”——-Yes Green Politics is a nasty old business.
Well, here’s an example of natural long-term energy storage (NLES). A picture’s worth a thousand words.
If even a little bit of the astronomical sums spent on renewables had been put into clean coal development we would not be seeing the enormous electricity bills we currently have, crippling the economy and leaving people unable to afford energy.
It’s blatant corruption and grifting. But since the corrupt grifters are in the House of Frauds or protected by the other corrupt grifters in Government, they’re untouchable.
As ever, follow the money. It was funny when the last offshore auction attracted zero bids – say what you like about the private sector, they tend not to invest in loss making ventures if they can help it, unlike our lovely government