New mega–meta-analysis on #LongCOVID ever prevalence.
Long COVID has affected 36% of people after a COVID-19 infection worldwide.
South America: 51%
Europe: 39%
Asia: 35%
USA: 29%🧵
Long COVID has affected 36% of people after a COVID-19 infection worldwide.
South America: 51%
Europe: 39%
Asia: 35%
USA: 29%🧵
Important note.
This 36% is “ever prevalence” - the share of people who at any point during follow-up had symptoms lasting ≥2 months after infection.
It does not mean they all still have symptoms today. Current prevalence is lower (eg 9% of US adults).
This 36% is “ever prevalence” - the share of people who at any point during follow-up had symptoms lasting ≥2 months after infection.
It does not mean they all still have symptoms today. Current prevalence is lower (eg 9% of US adults).
Why 2 months?
Different studies used different definitions of long COVID (WHO = 3 months, NASEM = 3 months, others = 2 months). To include the widest possible dataset, this meta-analysis defined long COVID as ≥1 new or persistent symptom lasting ≥2 months after infection.
Different studies used different definitions of long COVID (WHO = 3 months, NASEM = 3 months, others = 2 months). To include the widest possible dataset, this meta-analysis defined long COVID as ≥1 new or persistent symptom lasting ≥2 months after infection.
The key point - symptoms often persist for years.
That persistence itself is important - showing long COVID is not just a short-term aftermath, but a condition that can remain a serious health burden well beyond the initial infection.
That persistence itself is important - showing long COVID is not just a short-term aftermath, but a condition that can remain a serious health burden well beyond the initial infection.
And the data back this up
35% within 1 year
46% at 1-2 years
43% even beyond 2 years
This doesn’t mean new cases appear later - it shows some people remain sick for a long time, and longer studies often include more severe (hospitalized) cases.
35% within 1 year
46% at 1-2 years
43% even beyond 2 years
This doesn’t mean new cases appear later - it shows some people remain sick for a long time, and longer studies often include more severe (hospitalized) cases.
Risk factors.
No vaccination - OR 2.09 >2× higher risk than vaccinated
Pre-Omicron infection (Alpha/Delta) - OR 1.74 - higher risk than Omicron
Female sex: OR 1.56 - higher risk than male
Comorbidities
Cardiovascular disease (OR 1.50)
Hypertension (OR 1.37)
Any comorbidity (OR 1.52)
ICU admission: OR 1.43 - higher risk than non-ICU
No vaccination - OR 2.09 >2× higher risk than vaccinated
Pre-Omicron infection (Alpha/Delta) - OR 1.74 - higher risk than Omicron
Female sex: OR 1.56 - higher risk than male
Comorbidities
Cardiovascular disease (OR 1.50)
Hypertension (OR 1.37)
Any comorbidity (OR 1.52)
ICU admission: OR 1.43 - higher risk than non-ICU
Variants matter.
Pre-Omicron (Alpha/Delta) = higher risk.
Omicron = lower risk, especially in vaccinated people.
But many studies classified by calendar date (pre-Omicron vs Omicron), so effects of variants are partly blurred by vaccination rollout.
Pre-Omicron (Alpha/Delta) = higher risk.
Omicron = lower risk, especially in vaccinated people.
But many studies classified by calendar date (pre-Omicron vs Omicron), so effects of variants are partly blurred by vaccination rollout.
Most common subtypes:
Respiratory (20%)
Fatigue (20%)
Psychological (18%)
Neurological (16%)
Most common symptoms - memory problems (11%), muscle weakness (11%), breathlessness (8%), joint pain (7%), brain fog (4%).
Respiratory (20%)
Fatigue (20%)
Psychological (18%)
Neurological (16%)
Most common symptoms - memory problems (11%), muscle weakness (11%), breathlessness (8%), joint pain (7%), brain fog (4%).
Neurological impact stands out.
Unlike flu or other respiratory viruses, COVID often leaves memory loss, brain fog, and cognitive dysfunction behind.
Unlike flu or other respiratory viruses, COVID often leaves memory loss, brain fog, and cognitive dysfunction behind.
Insights.
Definition matters - any fatigue = 20%, severe/constant fatigue = 7% - a lot depends on how symptoms are defined - that’s why numbers vary so much between studies.
Massive heterogeneity between studies (I2 ≈ 100%) - different definitions of long COVID, different health systems, different viral variants, vaccination coverage, testing, and follow-up methods all shape the results.
Underrepresentation - very few studies from Africa & Oceania.
Definition matters - any fatigue = 20%, severe/constant fatigue = 7% - a lot depends on how symptoms are defined - that’s why numbers vary so much between studies.
Massive heterogeneity between studies (I2 ≈ 100%) - different definitions of long COVID, different health systems, different viral variants, vaccination coverage, testing, and follow-up methods all shape the results.
Underrepresentation - very few studies from Africa & Oceania.
Sum:
Long COVID is a global, long-term health challenge.
Vaccination and variants shape the risk - but millions remain affected.
Long COVID is a global, long-term health challenge.
Vaccination and variants shape the risk - but millions remain affected.
Hou at al., Global Prevalence of Long COVID, its Subtypes, and Risk factors: An Updated Systematic Review and Meta-Analysis. academic.oup.com/ofid/advance-a…
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