Throughout the pandemic, one of the key factors that scientists and health professionals have sought to understand is the scale and severity of Long COVID.
And while it's difficult to quantify exactly how many people will suffer from long-term symptoms, data published by the Office for National Statistics (ONS) this week suggests that a significant majority of adults do not experience ill effects longer than three months after becoming infected.
Researchers looked at data from more than 50,000 people, half of whom had tested positive for coronavirus.
In a blog explaining the data on the ONS website, it was suggested that the latest research should be viewed as "reassuring" as the majority of people infected with coronavirus (88% to 97%) do not experience symptoms beyond the first 12 weeks, and some of those who do will start to feel better over time.
However, for the minority of people who do go on to experience long-term symptoms, the effects can be debilitating, and figures suggest as many as 643,000 Britons could currently be affected by long COVID.
Another study this week also suggested that long COVID symptoms rarely persist beyond 12 weeks in children and adolescents, which may mean it is proportionally less of a concern than in adults.
For many, however, whether they even have long COVID is difficult to ascertain, particularly as there is no accepted understanding of what counts as having ‘long COVID’.
What is long COVID?
While the ONS report refers to the National Institute for Clinical Excellence (NICE) clinical definition for long COVID – "signs and symptoms that develop during or after an infection consistent with COVID-19 that continue for more than 12 weeks and are not explained by an alternative diagnosis" – it stresses that there is no absolute definition for the condition.
The ONS analysis asked two groups of people – those who had tested positive for coronavirus and those who had not – whether they had:
shortness of breath
loss of taste
loss of smell
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Around 3% of people who had tested positive had at least one of the symptoms for at least three months after infection, but among those who had not tested positive that proportion was 0.5%, meaning one in every 40 infected people had their coronavirus symptoms last for three months or longer.
What are the symptoms?
The NHS official guidance lists symptoms of long COVID as:
extreme tiredness (fatigue)
shortness of breath
chest pain or tightness
problems with memory and concentration ("brain fog")
difficulty sleeping (insomnia)
pins and needles
depression and anxiety
feeling sick, diarrhoea, stomach aches, loss of appetite
a high temperature, cough, headaches, sore throat, changes to sense of smell or taste
The World Health Organization has warned that our understanding of how to diagnose and manage long COVID is still evolving but the condition can be very debilitating.
The WHO lists some of the symptoms as including: generalised chest and muscle pain, fatigue, shortness of breath, chest pain, muscle aches, palpitations, persisting high temperature and cognitive dysfunction, among others.
How many people are getting long COVID?
While the ONS acknowledges it is difficult to assess exact numbers for those suffering long COVID it says that between 3% and 12% of people infected with coronavirus have symptoms 12 weeks after the initial infection; or between 7% and 18% when considering only people who were symptomatic at the acute phase of infection, meaning up to 97% of people may avoid it.
Commenting on the ONS findings, Professor Kevin McConway, emeritus professor of applied statistics at The Open University, said that while exact figures could not be given, some "crude calculations" were possible using the data.
“The ONS [survey] produces estimates of the incidence of new infection ," he said.
The latest set of data (for the week 14-20 August) gives a total estimate for the whole of the UK community population of 526,000 new infections that week.
Prof McConway said: "Tough that figure does have a wide margin of statistical error, if 3% of those new infections result in Long COVID, that’s getting on for 16,000 new Long COVID cases just from infection that week – and if the highest figure from the new ONS bulletin, 12% of the infections, result in long COVID, that would be over 60,000 new cases just from a week’s worth of infections across the UK."
However, he added: "It’s reassuring, of course, that most people who are infected don’t go on to develop long COVID, but in absolute numbers, really a lot of people will be developing a quite long-term illness."
Boris Johnson laid out the government's plan to tackle COVID over the winter months on Tuesday, but also warned a 'Plan B' could come into effect if the NHS looked to be under pressure.
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