When looking at symptoms among people five weeks after testing positive for Covid-19, the ONS estimated that 11.5 per cent of people were still experiencing fatigue, 11.4 per cent had a cough and 10 per cent had a headache.
The ONS said it estimated that during the week ending on 28 November, there were about 186,000 people in England living with Covid-19 symptoms that had lasted between five and 12 weeks.
This number could be as high as 221,000, the ONS warned. It said the data was experimental and based on the findings from its infection survey of households.
Just over 8 per cent were still experiencing a loss of taste, and 7.9 per cent still had a loss of smell.
The data could be the first indication of how prevalent long Covid is, with many patients reporting debilitating symptoms affecting them for many months after recovering from the initial infection.
NHS England has invested millions of pounds in establishing a network of more than 40 clinics in order to treat an estimated 60,000 long-Covid patients. If the ONS analysis is correct, the true prevalence could be significantly greater than previously thought.
The patients include those admitted to hospital but also many thousands who were never sick enough to go into hospital and who did not get a positive test result earlier in the year because of a lack of community tests.
Patients have reported multi-organ complications affecting not just their lungs but also their heart, brain and kidneys, and leaving them fatigued and unable to work, exercise or even leave their homes.
Many of those affected could be frontline NHS staff and care workers who have been exposed to the virus through their jobs.
The ONS said: “Although this research is in its infancy, we felt it important to publish our early results in order to fill an important gap in the evidence base, and to provide a basis for discussion from which to inform the future direction of the research.
“This is our first attempt at producing these estimates, and the analysis is very much a work in progress. We will seek to further refine the estimates, for example by using more sophisticated statistical techniques to account for the possibility of relapse and, should sample sizes allow, investigate symptoms persisting beyond 12 weeks.”
From next year, it will also add a new question to the national survey to ask people to say what the impact of long Covid has been on their day-to-day lives, with an expanded list of symptoms.
Looking at the complications following a diagnosis of coronavirus by analysing patients’ GP and hospital records, the ONS said it had compared adverse events experienced by hospital patients up to the end of September 2020 with those of similar patients who were not in hospital with Covid-19.
The ONS said that the former had elevated rates of heart, kidney and liver disease problems. It added that the rates of diabetes and heart disease were particularly high.
A report by the National Institute for Health Research (NIHR) in October warned of a widespread hidden impact of the coronavirus on patients who developed long Covid.
Some patients reported problems seven months on from their infection, with the range of symptoms varying significantly between cases.
The NIHR report warned that the NHS would need to develop whole new pathways to care for the patients, and described four separate syndromes that could make up long Covid: permanent damage to the lungs and heart, post-intensive care syndrome, post-viral fatigue and ongoing Covid-19 symptoms.
Dr Elaine Maxwell, author of the NIHR report, told The Independent that the ONS estimate could be lower than the reality.
She said: “The ONS plans to estimate the prevalence of long Covid are very welcome. In our review, we noted the wide range and fluctuation of symptoms. The current ONS Covid-19 infection survey tracks a limited number of symptoms over time and may therefore not be capturing everyone with ongoing problems.
“The estimate of 186,000 people in England may prove to be an underestimate and the introduction of a wider list and the opportunity for people to describe the impact of long Covid will hugely improve our understanding.”
She added that the ONS survey missed out vulnerable groups such as Travellers, the homeless, prisoners and care home residents.
“More work is needed to identify unmet need in these communities,” she said.
The National Institute for Health and Care Excellence is drafting new guidelines for the care and treatment of long-Covid patients.
Dr David Strain, a member of the NHS Long Covid taskforce, said: “These preliminary data are very concerning, suggesting that 10 per cent of people who have experienced Covid are left with residual symptoms after three months – more than twice the rate we previously thought. It also highlights that the majority of people who contract Covid have symptoms for over a month.”
He said the data on complications in hospital patients also confirmed “what we have seen, working on the Covid wards, that this virus is more than a simple respiratory infection, but is a multi-system disease”.
“This is happening to younger people, more women than men – basically the population that were suggested to be at lower vulnerability from the initial disease, and therefore have been taking roles with higher hazard of coming into contact with the virus. The long-term consequences for these individuals, and for the population as a whole, could be potentially devastating, in terms of physical manifestations for the individuals but also the economic impact of these individuals being unable to work.”