The way that data set is presented is infuriating – there are tables that list raw counts without reference to the sample size (maybe it’s an estimated raw number for the whole country, in which case they’re quite small)
This is the UK Office for National Statistics—their usual is to report estimated numbers for the whole country. Easy to miss but it’s in thousands—scroll to the far right of each table with raw numbers and you’ll see that stated near the top. So Table 1 estimates 1,332,000 UK residents with Long COVID, which is in line with the 2% figure stated in Table 4 if we assume that it’s talking about the whole country.
I presume this is listing their health conditions before Covid since it makes no sense the other way, but am still somewhat confused.
Footnote 7 says “Health/disability status is self-reported by study participants rather than clinically diagnosed. From February 2021 study participants were asked to exclude any symptoms related to COVID-19 when reporting their health/disability status. However, in practice it may be difficult for some participants to separate long COVID symptoms from unrelated exacerbation of pre-existing conditions, so these results should be treated with caution.”
What’s even stranger is this is now people who had Covid over 12 weeks ago, instead of the general population, and the estimate has gone down – 2.06% to 1.46%.
The title of the table can be parsed different ways, but pretty sure that what this table is showing is, “Of people living in private households with self-reported long COVID, what proportion of them say that they first had COVID at least 12 weeks previously” (1.46%). We can see from Footnote 1 that the definition of Long Covid for this study was “Would you describe yourself as having ‘long COVID’, that is, you are still experiencing symptoms more than 4 weeks after you first had COVID-19, that are not explained by something else?” So presumably the remaining 98.54% of people with self-reported long COVID said that they first had COVID at least 4 weeks but less than 12 weeks previously.
The table with the 2.06% is saying, “Of all people in the country, what percentage of them have long COVID of any duration”, i.e., 4 weeks or longer. So I don’t think there’s a contradiction here.
Matt Bell was referencing the UK data set above so I have no idea how he can get 2.8%, and in fact my reading of the link says he has it somewhat lower than that but still strangely high.
I also tried and failed to figure out how he gets this number.
There is a separate study by the Office for National Statistics with controls (a later one than the one Matt Bell mentions, with different methodology) that I found useful—report is here—though annoyingly it doesn’t break the data down by individual symptoms. Figures 1 and 2 also illustrative with respect to duration of symptoms. The report is pretty comprehensive but the data tables are here, Tables 1-4 show comparisons to controls.
Bottom line is summarized by the points at the top, reproduced below; note that only “Approach 3″ uses self-reported long COVID:
”Approach 1: Prevalence of any symptom at a point in time after infection. Among study participants with COVID-19, 5.0% reported any of 12 common symptoms 12 to 16 weeks after infection; however, prevalence was 3.4% in a control group of participants without a positive test for COVID-19, demonstrating the relative commonness of these symptoms in the population at any given time.
Approach 2: Prevalence of continuous symptoms after infection. Among study participants with COVID-19, 3.0% experienced any of 12 common symptoms for a continuous period of at least 12 weeks from infection, compared with 0.5% in the control group; this estimate of 3.0% is based on a similar approach to the one we published in April 2021 (13.7%), but is substantially lower because of a combination of longer study follow-up time and updated statistical methodology. The corresponding prevalence estimate when considering only participants who were symptomatic at the acute phase of infection was 6.7%.
Approach 3: Prevalence of self-reported long COVID. An estimated 11.7% of study participants with COVID-19 would describe themselves as experiencing long COVID (based on self-classification rather than reporting one of the 12 common symptoms) 12 weeks after infection, and may therefore meet the clinical case definition of post-COVID-19 syndrome, falling to 7.5% when considering long COVID that resulted in limitation to day-to-day activities; these percentages increased to 17.7% and 11.8% respectively when considering only participants who were symptomatic at the acute phase of infection.”
This is the UK Office for National Statistics—their usual is to report estimated numbers for the whole country. Easy to miss but it’s in thousands—scroll to the far right of each table with raw numbers and you’ll see that stated near the top. So Table 1 estimates 1,332,000 UK residents with Long COVID, which is in line with the 2% figure stated in Table 4 if we assume that it’s talking about the whole country.
Footnote 7 says “Health/disability status is self-reported by study participants rather than clinically diagnosed. From February 2021 study participants were asked to exclude any symptoms related to COVID-19 when reporting their health/disability status. However, in practice it may be difficult for some participants to separate long COVID symptoms from unrelated exacerbation of pre-existing conditions, so these results should be treated with caution.”
The title of the table can be parsed different ways, but pretty sure that what this table is showing is, “Of people living in private households with self-reported long COVID, what proportion of them say that they first had COVID at least 12 weeks previously” (1.46%). We can see from Footnote 1 that the definition of Long Covid for this study was “Would you describe yourself as having ‘long COVID’, that is, you are still experiencing symptoms more than 4 weeks after you first had COVID-19, that are not explained by something else?” So presumably the remaining 98.54% of people with self-reported long COVID said that they first had COVID at least 4 weeks but less than 12 weeks previously.
The table with the 2.06% is saying, “Of all people in the country, what percentage of them have long COVID of any duration”, i.e., 4 weeks or longer. So I don’t think there’s a contradiction here.
I also tried and failed to figure out how he gets this number.
There is a separate study by the Office for National Statistics with controls (a later one than the one Matt Bell mentions, with different methodology) that I found useful—report is here—though annoyingly it doesn’t break the data down by individual symptoms. Figures 1 and 2 also illustrative with respect to duration of symptoms. The report is pretty comprehensive but the data tables are here, Tables 1-4 show comparisons to controls.
Bottom line is summarized by the points at the top, reproduced below; note that only “Approach 3″ uses self-reported long COVID:
”Approach 1: Prevalence of any symptom at a point in time after infection. Among study participants with COVID-19, 5.0% reported any of 12 common symptoms 12 to 16 weeks after infection; however, prevalence was 3.4% in a control group of participants without a positive test for COVID-19, demonstrating the relative commonness of these symptoms in the population at any given time.
Approach 2: Prevalence of continuous symptoms after infection. Among study participants with COVID-19, 3.0% experienced any of 12 common symptoms for a continuous period of at least 12 weeks from infection, compared with 0.5% in the control group; this estimate of 3.0% is based on a similar approach to the one we published in April 2021 (13.7%), but is substantially lower because of a combination of longer study follow-up time and updated statistical methodology. The corresponding prevalence estimate when considering only participants who were symptomatic at the acute phase of infection was 6.7%.
Approach 3: Prevalence of self-reported long COVID. An estimated 11.7% of study participants with COVID-19 would describe themselves as experiencing long COVID (based on self-classification rather than reporting one of the 12 common symptoms) 12 weeks after infection, and may therefore meet the clinical case definition of post-COVID-19 syndrome, falling to 7.5% when considering long COVID that resulted in limitation to day-to-day activities; these percentages increased to 17.7% and 11.8% respectively when considering only participants who were symptomatic at the acute phase of infection.”