Researchers from the University of Oxford have analysed dozens of studies into long Covid to understand the scale and impact of the illness.

A new review published in The Lancet suggests the condition can affect all age groups, including children, and is more prevalent among the most deprived fifth of the UK population.

The team of researchers, which also included members from the Universities of Leeds and Arizona, focused on how many people were affected, the condition's biological mechanics, the symptoms patients develop and current and future treatments.

Long Covid is categorised as symptoms continuing for three months or more after initially contracting Covid-19.

The condition can affect and damage many organ systems, leading to severe and long-term impaired function and a broad range of symptoms including fatigue, cognitive impairment, breathlessness and pain.

The research found the rate of long Covid was considerably higher among the most underprivileged fifth of the UK population at 3.2 per cent, compared to only 1.5 per cent among the least deprived fifth.

Women were noted to be slightly more likely than men to develop the condition.

The researchers found while some people gradually get better from long Covid, in others the condition can persist for years.

Many people who contracted long Covid before vaccines were available remain unwell.

The risk of the condition reduces substantially if an individual has been fully vaccinated and is up to date with their boosters.

Those who have been fully vaccinated are less likely to develop long Covid, researchers sayThose who have been fully vaccinated are less likely to develop long Covid, researchers say (Image: PA)

However, three to five per cent of people still develop it following an acute Covid-19 infection.

An estimated 1.8 per cent of the UK population is impacted, with 71 per cent of these individuals having had the condition now for longer than a year.

Biological mechanisms such as the virus's persistence within the body, disruption of the normal immune response and microscopic blood clotting play a role in long Covid's development.

There are no proven treatments yet, and current management of the condition focuses on ways to relieve symptoms or provide rehabilitation.

Professor of Primary Care Health Sciences at Oxford's Nuffield Department, Trisha Greenhalgh, said: "Long Covid is a dismal condition but there are grounds for cautious optimism.

"Various mechanism-based treatments are being tested in research trials.

"If proven effective, these would allow us to target particular sub-groups of people with precision therapies.

"Treatments aside, it is becoming increasingly clear that long Covid places an enormous social and economic burden on individuals, families and society.

"In particular, we need to find better ways to treat and support the ‘long-haulers' - people who have been unwell for two years or more and whose lives have often been turned upside down."