by University of Oxford

Credit: Unsplash/CC0 Public Domain

In a new review paper, researchers from the Universities of Oxford, Leeds and Arizona, analyzed dozens of previous studies into long COVID to examine the number and range of people affected, the underlying mechanisms of disease, the many symptoms that patients develop, and current and future treatments.

The paper "Long COVID: a clinical update" is published in The Lancet.

Long COVID, also known as Post-COVID-19 condition, is generally defined as symptoms persisting for three months or more after acute 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 (often referred to as 'brain fog'), breathlessness and pain.

Long COVID can affect almost anyone, including all age groups and children. Strikingly, the rate of long COVID in the most deprived fifth of the UK population (3.2%) is more than twice as high as that in the least deprived fifth (1.5%). Women are slightly more likely than men to be affected.

The researchers found that while some people gradually get better from long COVID, in others the condition can persist for years. Many people who developed long COVID before the advent of vaccines are still unwell. If a person has been fully vaccinated and is up to date with their boosters, their risk of long COVID is much lower.

However, 3–5% of people still develop long COVID after an acute COVID-19 infection. In the UK alone, long COVID affects an estimated 1.8% of the population, and 71% of people with the condition have now had it for more than a year.

They also found that a wide range of biological mechanisms are involved, including persistence of the original virus in the body, disruption of the normal immune response, and microscopic blood clotting, even in some people who had only mild initial infections.

There are no proven treatments for long COVID yet, and current management of the condition focuses on ways to relieve symptoms or provide rehabilitation. There is a dire need to develop and test biomarkers (e.g. blood tests) to diagnose and monitor long COVID and to find therapies that address root causes of the disease.

People can lower their risk of developing long COVID by avoiding infection (e.g. by wearing a close-fitting mask in crowded indoor spaces), taking antivirals promptly if they do catch COVID-19, avoiding strenuous exercise during such infections, and ensuring they are up to date with their COVID vaccines and boosters.

Trisha Greenhalgh, Professor of Primary Care Health Sciences at Oxford's Nuffield Department of Primary Care Health Sciences, 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."

More information: Trisha Greenhalgh et al, Long COVID: a clinical update, The Lancet (2024). DOI: 10.1016/S0140-6736(24)01136-X

Journal information: The Lancet 

Provided by University of Oxford