First of all, I’m sorry to hear about your disability from long COVID. From my reading on the symptoms, it sounds like a terrible experience, particuarly as for you it has dragged on for so long.
From your “conservative estimate” link, dated March 3, 2022:
Of [1.5 million] people with self-reported long COVID, 344,000 (22%) first had (or suspected they had) COVID-19 less than 12 weeks previously, 1.1 million (71%) first had (or suspected they had) COVID-19 at least 12 weeks previously, and 685,000 (45%) first had (or suspected they had) COVID-19 at least one year previously.
The percentages total to 138%, which is confusing because the criteria for “date of first (suspected) COVID-19 infection” is defined in such a way as to avoid two answers being true for one person.
These time brackets would be approximately Jan-March, 2022, March-Dec, 2021, and prior to March 2021, respectively. Looking at the cumulative confirmed cases for the UK, these brackets correspond to 7.55 million, 8.76 million, and 4.2 million people. Delta became the dominant strain in the UK in mid-June, 2021, while Omicron became dominant in mid-December, 2021. Because confirmed cases were nearly flat prior to Delta’s emergence, these three time phases fairly closely correspond to the periods of dominance of Omicron, Delta, and Alpha strains, respectively. I will therefore refer to them as the “Omicron phase,” “Delta phase,” and “Alpha phase” going forward.
Of 20.68 million total confirmed UK cases, the Omicron phase is about 37% of cases, Delta is about 42% of cases, and Alpha was about 20% of cases.
Given that the percentages above total to 138%, I’m not sure if the following analysis is valid. But I’ll run with it. Based on the given percentages, Omicron is significantly underrepresented in terms of long COVID cases relative to total Omicron cases. Delta and especially Alpha are overrepresented in terms of long COVID. This tracks with the idea that severity of illness, due both to the intrinsic severity of the virus and to vaccine and treatment availability, has been an important driver of long COVID.
Risk factors for not returning to “usual health” included age (P=0.01), with the ≥50 years age group having the greatest odds ratio, and number of pre-existing medical conditions (P=0.003), with a greater number of conditions associated with a greater odds ratio of not returning to “usual health.” Of the pre-existing conditions, having hypertension (odds ratio (OR)=1.3, P=0.018), obesity (OR=2.31, P=0.002), a psychiatric condition (OR=2.32, P=0.007), or an immunosuppressive condition (OR=2.33, P=0.047) corresponded with the greatest odds of not returning to “usual health.”18
A cross sectional study identified an association between the severity of acute covid-19 infection and post-recovery manifestations in people who have had covid-19, showing that a more severe acute phase may transform into the development of more severe symptoms of long covid.43 A cohort study, meanwhile, corroborated this finding, with patients with more than five symptoms during the initial covid-19 infection and those that required hospital admission more likely to experience long covid symptoms.34
Based on this, claiming that the reader’s individual risk of long COVID corresponds to the population rates seems somewhat misleading, if an understandable place to start thinking about the question. We have data that allows the reader to consider whether or not they are likely to be in a relatively low- or high-risk group for long COVID. Studies exist showing no association between COVID severity and long COVID risk, but I haven’t done any kind of a deep dive here and it would be worth looking into more deeply.
If severity of COVID does correspond to prevalence of long COVID, then we can expect continued lower rates of long COVID in the future as treatments improve and become more accessible, particularly if COVID retains its current relatively mild individual severity over the long term. There is no guarantee that it will, but we can continue to monitor for new, more infectious and more severe strains, while resuming normal life in the meantime.
These are only my first thoughts on poking into a couple of your links. I’m particularly interested in updated and better information on:
Anys link or evidence against links between COVID severity/strain/treatment and long COVID
The distribution of long COVID duration
Long COVID severity by symptom (i.e. if sufferers experience fatigue, what is the distribution of fatigue severity?)
Evidence of long COVID rates and risks based on clinical diagnosis rather than self-reported data
Awesome in depth response! Yes, I was hoping this post to serve as an initial alarm bell to look further into, rather than being definitive advice based on a comprehensive literature review.
I can’t respond to everything, at least not at once, but here’s some:
categories of ‘at least 12 weeks’ and ‘at least 1 year’ do overlap, right?
I think the different waves may have had different underreporting factors, with least underreporting during Delta, so we can’t take those rates at face value, and I prefer using estimated cases whenever possible
The wording is “less than 12 weeks” rather than “at least 12 weeks,” so the categories shouldn’t overlap, time wise. Under the theory that omicron is underreported and delta more accurately reported, this bolsters the case for long COVID being linked to disease severity—with the caveat about the percentages not adding to 100% in mind.
Uhm, no? I’m quoting you on the middle category, which overlaps with the long category.
I see what you mean. The study’s criteria, which I didn’t quote here, states that the earliest time at which the respondant met any of the conditions for a COVID infection should be counted. I remain confused (not by you, by the UK study)!
Also, there’s no need to speculate, because there have been studies linking severity and viral load to increased risk of long COVID.
I don’t see myself as speculating, so much as emphasizing that contradictory evidence exists even about the association, not to mention causality.
First of all, I’m sorry to hear about your disability from long COVID. From my reading on the symptoms, it sounds like a terrible experience, particuarly as for you it has dragged on for so long.
From your “conservative estimate” link, dated March 3, 2022:
The percentages total to 138%, which is confusing because the criteria for “date of first (suspected) COVID-19 infection” is defined in such a way as to avoid two answers being true for one person.
These time brackets would be approximately Jan-March, 2022, March-Dec, 2021, and prior to March 2021, respectively. Looking at the cumulative confirmed cases for the UK, these brackets correspond to 7.55 million, 8.76 million, and 4.2 million people. Delta became the dominant strain in the UK in mid-June, 2021, while Omicron became dominant in mid-December, 2021. Because confirmed cases were nearly flat prior to Delta’s emergence, these three time phases fairly closely correspond to the periods of dominance of Omicron, Delta, and Alpha strains, respectively. I will therefore refer to them as the “Omicron phase,” “Delta phase,” and “Alpha phase” going forward.
Of 20.68 million total confirmed UK cases, the Omicron phase is about 37% of cases, Delta is about 42% of cases, and Alpha was about 20% of cases.
Given that the percentages above total to 138%, I’m not sure if the following analysis is valid. But I’ll run with it. Based on the given percentages, Omicron is significantly underrepresented in terms of long COVID cases relative to total Omicron cases. Delta and especially Alpha are overrepresented in terms of long COVID. This tracks with the idea that severity of illness, due both to the intrinsic severity of the virus and to vaccine and treatment availability, has been an important driver of long COVID.
This is older than I’d like (July 2021), but it’s a place to start. Long covid—mechanisms, risk factors, and management
Based on this, claiming that the reader’s individual risk of long COVID corresponds to the population rates seems somewhat misleading, if an understandable place to start thinking about the question. We have data that allows the reader to consider whether or not they are likely to be in a relatively low- or high-risk group for long COVID. Studies exist showing no association between COVID severity and long COVID risk, but I haven’t done any kind of a deep dive here and it would be worth looking into more deeply.
If severity of COVID does correspond to prevalence of long COVID, then we can expect continued lower rates of long COVID in the future as treatments improve and become more accessible, particularly if COVID retains its current relatively mild individual severity over the long term. There is no guarantee that it will, but we can continue to monitor for new, more infectious and more severe strains, while resuming normal life in the meantime.
These are only my first thoughts on poking into a couple of your links. I’m particularly interested in updated and better information on:
Anys link or evidence against links between COVID severity/strain/treatment and long COVID
The distribution of long COVID duration
Long COVID severity by symptom (i.e. if sufferers experience fatigue, what is the distribution of fatigue severity?)
Evidence of long COVID rates and risks based on clinical diagnosis rather than self-reported data
Awesome in depth response! Yes, I was hoping this post to serve as an initial alarm bell to look further into, rather than being definitive advice based on a comprehensive literature review.
I can’t respond to everything, at least not at once, but here’s some:
categories of ‘at least 12 weeks’ and ‘at least 1 year’ do overlap, right?
I think the different waves may have had different underreporting factors, with least underreporting during Delta, so we can’t take those rates at face value, and I prefer using estimated cases whenever possible
The wording is “less than 12 weeks” rather than “at least 12 weeks,” so the categories shouldn’t overlap, time wise. Under the theory that omicron is underreported and delta more accurately reported, this bolsters the case for long COVID being linked to disease severity—with the caveat about the percentages not adding to 100% in mind.
Uhm, no? I’m quoting you on the middle category, which overlaps with the long category.
Also, there’s no need to speculate, because there have been studies linking severity and viral load to increased risk of long COVID. https://www.cell.com/cell/fulltext/S0092-8674(22)00072-1
I see what you mean. The study’s criteria, which I didn’t quote here, states that the earliest time at which the respondant met any of the conditions for a COVID infection should be counted. I remain confused (not by you, by the UK study)!
I don’t see myself as speculating, so much as emphasizing that contradictory evidence exists even about the association, not to mention causality.