A third of people with COVID-19 symptoms develop 'long COVID' that lasts for 12 weeks, a new survey of 500,000 people suggests

• One in three people with symptomatic COVID-19 develop "long COVID," study suggests.
• The survey of 500,000 people checked for symptoms that lasted longer than 12 weeks.
• The researchers estimated 2 million people in England were COVID-19 long-haulers, double other estimates.

More people than previously thought are COVID-19 long-haulers, according to figures from a new survey of more than half a million people in England.

Researchers from Imperial College London found that about one in three people who caught COVID-19 with symptoms that impacted their daily lives went on to have "long COVID," defined by the group as at least one self-reported symptom lasting for more than 12 weeks.

Those who received hospital treatment were more likely to experience long-lasting symptoms than those who didn't, the authors said in a paper posted Thursday.

Women and older people were most likely to be affected, they said. Heavier people, smokers, people on low incomes, and those with long-term medical conditions had the highest risk, they found.

The researchers estimated that as many as 2 million people had long COVID in England, almost double the number estimated by the Office for National Statistics (ONS), at 741,000 people.

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The findings come from the REACT-2 study, a community-based survey of more than 500,000 adults commissioned by the Department of Health and Social Care. It's not clear how badly the symptoms affected people's lives.

Professor Paul Elliott, director of the REACT programme, said the results "paint a concerning picture of the longer-term health consequences of COVID-19."

The Imperial College researchers said in the paper that the results could be an overestimate, because some of the 29 symptoms they asked about could occur in other conditions. They also didn't compare the results with people who hadn't caught COVID-19, they said.

Kevin McConway, emeritus professor of Applied Statistics at the Open University, who was not involved in the research, said in a statement to the Science Media Centre that the main reason for the discrepancy between the new findings and the ONS results was that they estimated slightly different things. The ONS estimated the number of people who had long COVID on a particular date (May 2), while REACT-2 gave measured how many people had long COVID at some time between September 2020 and February 2021, he said.

Despite this, the REACT estimate was still higher, he added.