I agree it makes sense to split into two components. Your first component could be called “mild but long COVID”. By “mild”, I just mean the person didn’t ever require extensive hospital care. The second component sounds like permanent damage due to acute COVID. People with acute COVID were hospitalized and often spent long periods in intensive care. My thoughts/questions for you:
Mild+long COVID (1st component)
Studies: I haven’t seen any rigorous, large-scale study that tries to estimate how common this is. How to do a study? Ideally there’s a natural experiment, where you can compare matched populations with high vs low COVID rates (e.g. Milan vs. Rome, SF vs. LA, Stockholm vs Oslo). Failing that, you at least sample randomly from all people who had COVID using antibody tests or population PCR testing and then find a demographically matched control group. You take objective measures of their condition, e.g. employment, sick days, fitness test, and various medical tests of health. A “quick and dirty” approach is to find workplaces where a high proportion tested positive (hospitals in first wave in London/Lombardy/Madrid/Wuhan, meat plants, sports teams) and find out what proportion of people are back at work full-time.
Demographics: From existing (flawed) studies and surveys, it seems to be more common in middle age than say 10-15 year olds and 60+ year olds. It seems more common among women (perhaps more than 2:1), which I believe fits some other post-viral or auto-immune conditions. If this holds up, it might give some update in terms of personal risk.
Duration: You give a 6-month expected duration. How did you estimate this? The reference class for this component is presumably post-viral and auto-immune conditions, which (IIRC) have a longer than 6-month expected duration. Presumably you are updating on actual evidence from Long COVID sufferers. (There’s also various reports of people who experienced mild symptoms having some organ damage on examination. This might also suggest a more than 6-month duration for full recovery.)
Chronic Post-Acute COVID (2nd component)
Studies. There seem to be more studies of this component because you just need to follow up with people who were hospitalized and so there aren’t the same sampling issues. The UK is doing a large study on this. The reference class for this study is (presumably) people suffering from the conditions caused by acute COVID, which include pneumonia, ARDS, cytokine storm, vascular problems, etc. I think there aren’t large absolute numbers of people in their 20s without comorbidity who were hospitalized in any one location, and so getting a well-powered study on them might be non-trivial.
Demographics. Severity rates for COVID are very sensitive to age and somewhat sensitive to comorbidity. Does your 0.5% estimate take this into account? I can imagine that for someone in their 20s without comorbidity, the rate of chronic damage from acute COVID would be less than 0.5%. (For such people, I’d guess death rate is < 1⁄5000 and that permanent damage is less than 10x more likely than that. But I’m fairly uncertain about this.)
Future treatment: If the rates of these two kinds of post-COVID are as high as you estimate (0.5% and 3%), then there will be millions of people across Europe/US/Mexico etc. with these conditions. So there will be a huge incentive to improve treatments. Maybe some kinds of “permanent” damage are very hard to ameliorate, but if you’re doing the projection out for 20-30 years from today, I’d be optimistic. (It seems that hospital treatment for COVID has already improved significantly. There’ll be lots more cases in the next 6 months and so further improvements are expected).
Which study were you looking at?
I agree it makes sense to split into two components. Your first component could be called “mild but long COVID”. By “mild”, I just mean the person didn’t ever require extensive hospital care. The second component sounds like permanent damage due to acute COVID. People with acute COVID were hospitalized and often spent long periods in intensive care. My thoughts/questions for you:
Mild+long COVID (1st component)
Studies: I haven’t seen any rigorous, large-scale study that tries to estimate how common this is. How to do a study? Ideally there’s a natural experiment, where you can compare matched populations with high vs low COVID rates (e.g. Milan vs. Rome, SF vs. LA, Stockholm vs Oslo). Failing that, you at least sample randomly from all people who had COVID using antibody tests or population PCR testing and then find a demographically matched control group. You take objective measures of their condition, e.g. employment, sick days, fitness test, and various medical tests of health. A “quick and dirty” approach is to find workplaces where a high proportion tested positive (hospitals in first wave in London/Lombardy/Madrid/Wuhan, meat plants, sports teams) and find out what proportion of people are back at work full-time.
Demographics: From existing (flawed) studies and surveys, it seems to be more common in middle age than say 10-15 year olds and 60+ year olds. It seems more common among women (perhaps more than 2:1), which I believe fits some other post-viral or auto-immune conditions. If this holds up, it might give some update in terms of personal risk.
Duration: You give a 6-month expected duration. How did you estimate this? The reference class for this component is presumably post-viral and auto-immune conditions, which (IIRC) have a longer than 6-month expected duration. Presumably you are updating on actual evidence from Long COVID sufferers. (There’s also various reports of people who experienced mild symptoms having some organ damage on examination. This might also suggest a more than 6-month duration for full recovery.)
Chronic Post-Acute COVID (2nd component)
Studies. There seem to be more studies of this component because you just need to follow up with people who were hospitalized and so there aren’t the same sampling issues. The UK is doing a large study on this. The reference class for this study is (presumably) people suffering from the conditions caused by acute COVID, which include pneumonia, ARDS, cytokine storm, vascular problems, etc. I think there aren’t large absolute numbers of people in their 20s without comorbidity who were hospitalized in any one location, and so getting a well-powered study on them might be non-trivial.
Demographics. Severity rates for COVID are very sensitive to age and somewhat sensitive to comorbidity. Does your 0.5% estimate take this into account? I can imagine that for someone in their 20s without comorbidity, the rate of chronic damage from acute COVID would be less than 0.5%. (For such people, I’d guess death rate is < 1⁄5000 and that permanent damage is less than 10x more likely than that. But I’m fairly uncertain about this.)
Future treatment: If the rates of these two kinds of post-COVID are as high as you estimate (0.5% and 3%), then there will be millions of people across Europe/US/Mexico etc. with these conditions. So there will be a huge incentive to improve treatments. Maybe some kinds of “permanent” damage are very hard to ameliorate, but if you’re doing the projection out for 20-30 years from today, I’d be optimistic. (It seems that hospital treatment for COVID has already improved significantly. There’ll be lots more cases in the next 6 months and so further improvements are expected).