People who have been seriously ill and treated in intensive care units can wait a few months to fully recover, regardless of their condition.
However, with COVID-19, the evidence is mounting that some people who have had relatively mild symptoms at home may also have prolonged illness.
Overwhelming fatigue, palpitations, muscle aches, pins and needles, and many more symptoms are reported as sequelae of the virus. About 10 percent of the 3.9 million people who contribute to the COVID Symptom Study app have effects that last more than four weeks.
Chronic fatigue, classified as fatigue lasting more than six weeks, is recognized in many different clinical settings, from cancer treatment to inflammatory arthritis. It can be disabling.
If 1 percent of the 290,000 people who have had COVID-19 in the UK remain under the weather for three months, this will mean thousands of people will not be able to return to work. They will likely have complex needs that the NHS is not prepared to address today.
COVID-19 is not the only cause of chronic fatigue. Prolonged fatigue is well recognized after other viral infections like Epstein-Barr virus, which causes infectious mononucleosis (also known as glandular fever). Post-viral fatigue was also seen in a quarter of people infected with the original Sars virus in Hong Kong in 2003.
When it comes to treating chronic fatigue, the emphasis had previously been placed on the effective treatment of the underlying disease, in the belief that this would decrease fatigue. However, for most viral infections there is no specific treatment, and because COVID-19 is so new, we still don’t know how to manage post-COVID fatigue.
What could be causing post-COVID fatigue?
Although we know that lasting fatigue can sometimes follow other viral infections, for the most part a detailed mechanistic view is lacking. An ongoing viral infection in the lung, brain, fat, or other tissue may be a mechanism. A prolonged and inappropriate immune response after the infection has been cleared could be another.
However, a previous study has given us an idea. When people were given a chemical called interferon alpha as a treatment for hepatitis C, it caused flu-like illness in many patients and post-viral fatigue in a few.
Researchers have studied this “response to artificial infection” as a model of chronic fatigue. They found that basal levels of two molecules in the body that promote inflammation (interleukin-6 and interleukin-10) predicted the subsequent development of people’s chronic fatigue.
Of particular interest, these same proinflammatory molecules are seen in the “cytokine storm” of severely ill COVID-19 patients. This suggests that there could be a pattern of activation of the immune system during viral infection that is relevant to ongoing symptoms.
The successful use of tocilizumab, a treatment that reduces the impact of interleukin-6 and reduces inflammation, for the treatment of severe COVID-19, is additional support for interleukin-6 to play some role.
What should happen next
At TwinsUK at King’s College London, we investigated the genetic and environmental factors that influence disease by studying twins. We are using the COVID Symptom Study app to examine the reported long-lasting symptoms.
We are sending questionnaires to volunteer adult twins in our database, many of which were previously included in studies of the immune system long before the coronavirus epidemic. Our goal is to define “post-COVID syndrome” and look at the markers in the blood to shed more light on the immune mechanisms that contribute to long-term symptoms.
This will be a difficult study to design: People with COVID-19 have had more than just a viral infection in the normal way things work. His illness has taken place during unprecedented social change, movement restriction, and a time of great anxiety and risks hard to quantify, all accompanied by continuous 24-hour news.
Some patients have been very ill at home and believed they were close to death. For this reason, we will also examine post-traumatic stress, as the interpretation of reported symptoms must be established in context.
Chronic fatigue is not within the purview of a single medical specialty, so it is often overlooked in medical school curricula, and physicians are poorly trained in the diagnosis and management of chronic fatigue . But recent progress has been made, and online training is available for physicians that covers how to care for at least those with the most severe symptoms.
A guide for patients on managing chronic fatigue and how to conserve energy is also available. The important thing to note is that taking out a gym membership and exercising is the wrong thing to do and can slow people down considerably.
Small efforts, mental or physical, must be followed by rest. Returning to work, when it happens, should be a gradual and gradual process. Learning to carry out activities is very much the order of the day. 
Frances Williams, Professor of Genomic Epidemiology and Honorary Consultant Rheumatologist, King’s College London.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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