How many people have long Covid, and why do estimates differ so much?
Depending on who counts, long Covid affects 2.4% of people, or 6%, or 15%. The gap is the story.
How many people have long Covid? There is no single agreed number, and the honest answer is that estimates range widely. In its fact sheet of 26 February 2025, the World Health Organization says global estimates indicate that 6 in 100 people with Covid-19 develop post Covid-19 condition. An August 2024 review estimated that long Covid affects about 6-7% of adults and about 1% of children, and that roughly 400 million people had or have had it by the end of 2023. But other studies give very different figures.
Here are some of them. In February 2023 the UK's Office for National Statistics, using , reported that 2.4% of adults and 0.6% of children and young people reported long Covid following a second infection. A prospective study by Statistics Canada identified a cumulative of 15% after a first infection. In a large Scottish study, 42% of respondents said they had not fully recovered 6 to 18 months after catching Covid, and 6% said they had not recovered at all. These numbers do not measure the same thing, which is why they cannot be lined up as if they did.
Try it
Each infection, another chance (a simple model)
y = 1 · 0.85ˣ
Challenge · At 0.85 (a 15% risk each time), read the share never affected after 2 and 3 infections. Subtract it from 1: how close is it to Statistics Canada's 27% and 38%?
Why do they differ? Estimates of how common long Covid is vary widely depending on the definition used, the population studied and other methodological differences. Estimates based on statistically of the population are much lower than those based on certified infection, which tends to skew towards more serious cases, including hospitalised patients. And because appears to correlate with severity of infection, it is lower in vaccinated groups, on reinfection and during the omicron era, so the time of data collection matters.
Four estimates, four different questions
| Share | |
|---|---|
| UK ONS: after a second infection (adults) | 2.4% |
| WHO: people with Covid-19 | 6% |
| Statistics Canada: after a first infection | 15% |
| Scotland: not fully recovered at 6-18 months | 42% |
The WHO says more recent research shows the chances of developing post Covid-19 condition have reduced, but these data are limited and mostly from high-income countries. The figures describe populations, not what will happen to any one person.
Quiz me
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Recap
Estimates range from 2.4% to 15% and more because the question, the sample and the date differ.
💡 A trick to remember it · Same ruler, different rooms: a headline number only means something if you know what was counted and when.
Surprising fact · About 400 million people were estimated to have had long Covid by the end of 2023, per an August 2024 review.
Connects to
Sources (2)
No source, no claim. Every fact in this lesson (14 claims) cites at least one of these.