More than two million people in England may have had long Covid, new data suggests.
Findings from the React-2 studies show more than one third of people who had coronavirus reported symptoms lasting at least 12 weeks.
This amounts to 5.8% of the whole study population, with 2% reporting severe symptoms.
Researchers found the prevalence of long Covid increased with age and was higher among women.
The findings are based on self-reported data from 508,707 adults aged 18 and over who took part in rounds three to five of Imperial College London’s React-2 study carried out between September 2020 and February 2021.
Around a fifth of those surveyed reported having had a coronavirus symptom previously, with more than a third reporting persistent symptoms lasting at least 12 weeks.
Around a tenth of those with symptoms said they lasted at least 12 weeks and were severe.
Researchers say the findings suggest prevalence of persistent symptoms, or long Covid, increases with age, with a 3.5% increase in likelihood in each decade of life.
The study, which is yet to be peer-reviewed, indicates that long Covid is higher among women, people who are overweight or obese, those who smoke, people who live in deprived areas, or those who had been admitted to hospital.
According to the research, persistent Covid-19 symptoms were lower in people of Asian ethnicity.
Professor Paul Elliott, director of the React programme at Imperial, said: “Our findings do paint a concerning picture of the longer-term health consequences of Covid-19, which need to be accounted for in policy and planning.
“Long Covid is still poorly understood but we hope through our research that we can contribute to better identification and management of this condition, which our data and others’ suggest may ultimately affect millions of people in the UK alone.”
Asked how long symptoms of long Covid might last, Prof Elliott told a press briefing: “There are studies looking at specific elements of post-Covid syndrome.
I don’t know. For some people I think they will have long-term consequences. What we don’t know is what the numbers are going to be.”
Helen Ward, Professor of Public Health, Imperial College London, added: “We don’t know how long it might last because we haven’t been here before.”
People with persistent symptoms at 12 weeks fell into two broad groups, researchers found.
In the first, the most common symptoms were tiredness and muscle aches.
The most common symptoms in the second group were shortness of breath affecting normal activities, tightness in the chest, and chest pain, with more people reporting that they had severe symptoms.
But the study was based on self-reported data and because many of the symptoms are common and not specific to the virus, it may overestimate the prevalence of persistent symptoms following Covid-19.
Health Secretary Matt Hancock said: “Long Covid can have a lasting and debilitating impact on the lives of those affected.
“Studies like this help us to rapidly build our understanding of the impact of the condition and we are using these findings and other new research to develop support and treatments.
“We are learning more about long Covid all the time and have made £50 million of research funding available to support innovative projects, with clinics established across the country to help improve the treatment available.”
To help people suffering the debilitating long-term effects of this virus, the NHS has opened more than 80 long Covid assessment services across England.
Last week, the NHS published a £100 million plan to expand support, including £30 million to help GPs improve diagnosis and care for patients with long Covid.
A separate study led by UCL and King’s College London researchers suggests that one in six (17%) middle-aged people who report being infected by coronavirus also report long Covid symptoms.
This falls to one in 13 (7.8%) among younger adults who reported having Covid-19.
The preliminary findings, part of the UKRI-NIHR funded multi-institution Convalescence study and submitted to the preprint server medRxiv, also found that women were 50% more likely to report long Covid than men.
It also found that the risk for long Covid symptoms increases with age, is linked to poorer pre-pandemic mental and physical health and is associated with a previous diagnosis of asthma.
Non-white ethnic minority groups had lower odds of reporting long Covid (about 70% less likely).
Professor Nishi Chaturvedi, MRC Unit for Lifelong Health and Ageing at UCL - who leads the ongoing Convalescence study, said: “Getting consistent findings from this combination of many different studies gives us greater confidence that our findings are robust, which is critical given that we know so little about long Covid.”