• A study in England looking at persistent Covid-19 symptoms suggests that around 2 million people in the country may have had the condition known as "long Covid."
• The study, part of Imperial College London's REACT research which is tracking the virus in England, saw 508,707 people asked whether they'd had Covid (confirmed or suspected).
• They were then asked about the presence and duration of 29 different symptoms linked to the virus.

A study in England looking at persistent Covid-19 symptoms suggests that around 2 million people in the country may have had the condition known as "long Covid."

The study, part of Imperial College London's REACT research which is tracking the virus in England, saw 508,707 people across the country of roughly 56 million asked whether they'd had Covid (confirmed or suspected), and asked about the presence and duration of 29 different symptoms linked to the virus.

Among the 76,155 participants that said they had experienced a symptomatic Covid infection, 37.7% said they experienced at least one symptom lasting 12 weeks or more, while almost 15% of people said they had experienced three or more symptoms lasting 12 weeks or more.

The symptoms of long Covid can vary, with people reporting ongoing fatigue, shortness of breath, memory loss or problems with concentration (dubbed "brain fog"), insomnia, chest pain or dizziness, as well as other symptoms. But it is still poorly understood and scientists don't yet know why some people continue to have symptoms post-Covid, and others none.

"In this large community-based study of symptoms following Covid-19 among adults aged 18 years and above in England, participants reported high prevalence of persistent symptoms lasting 12 weeks or more," the researchers at Imperial noted of their latest study.

Extrapolating the findings in the study to the wider Covid backdrop in England, where there have been 4.07 million Covid cases confirmed to date, the study could mean that over 2 million adults who have had the virus in England may have experienced some form of long Covid.

"Estimates ranged from 5.8% of the population experiencing one or more persistent symptoms post-Covid-19 (corresponding to over 2 million adults in England), to 2.2% for three or more persistent symptoms (just under a million adults in England)," the researchers noted.

They said that their estimates of the proportion of people with persistent Covid symptoms were higher than in many other studies, although previous estimates have varied widely.

"Our comparatively high estimate, at 37.7% of people with Covid-19 experiencing one or more symptoms at 12 weeks, may partly reflect the large list of symptoms we surveyed, many of which are common and not specific to Covid-19. However, we asked participants only about symptoms that they related to a confirmed or suspected episode of Covid-19, and not to symptoms more generally."

Scientists are still investigating long Covid, and experts have urged the British government to address its public health implications; the National Health Service has opened long Covid assessment centers, for example.

"A substantial proportion of people with symptomatic Covid-19 go on to have persistent symptoms for 12 weeks or more, which is age-dependent. Clinicians need to be aware of the differing manifestations of Long Covid which may require tailored therapeutic approaches," researchers at Imperial said.

The survey data was collected between Sept. 15 last year and Feb. 8 and the study is a preprint, and has not yet been peer-reviewed or published in a journal.