The Link Between Long COVID and Chronic Fatigue Syndrome

13 May 2021

The National Institute for Health and Care Excellence (NICE) guidelines describe long COVID as ‘signs and symptoms that develop during or following an infection consistent with COVID-19 and which continue for more than four weeks and are not explained by an alternative diagnosis. After 12 weeks, NICE recommends using the term ‘post-COVID syndrome’ to describe the condition. However, the use of the word ‘post’ implies that the acute infection, and any active disease associated with it, has resolved. In reality, it is not currently known whether this is indeed the case.

It has been estimated that around one in five people who are initially infected with COVID-19 will exhibit symptoms for at least five weeks, and in around 10% of patients, symptoms will continue for 12 weeks or more. This means that upwards of 60,000 people in the UK are currently living with the effects of long COVID. This experience is not just restricted to those who are hospitalised by their initial infection, although those whose disease is characterised by a higher number of symptoms during the first week do seem to be more prone. Other risk factors include older age and being female. Asthmatics also appear to be more likely to develop long COVID, but no other links to existing diseases have been found.

The symptoms associated with COVID-19 cover a broad spectrum, and it has been suggested that the condition actually consists of up to four separate syndromes. Symptoms include life-threatening conditions such as Guillain-Barre Syndrome, encephalitis and heart conditions, along with less devastating symptoms such as debilitating fatigue, especially after exertion, pain extending throughout the body, cognitive dysfunction (‘brain fog’), headaches, nerve pain and tingling, breathlessness and generalised weakness. There are remarkable similarities in the symptoms and experiences of people with long COVID and those suffering from chronic fatigue syndrome (CFS). Interestingly, every one of the less serious symptoms of COVID-19 has also been described as a symptom of CFS, and most of the symptoms associated with CFS have been experienced by at least some COVID-19 patients, particularly those who have gone on to develop long COVID. However, while long COVID has been readily accepted as a real entity, controversy still surrounds the diagnosis of CFS.

Around 80% of CFS cases are the result of an infection, although the condition may also arise after surgery or a traumatic injury. It is thought that viral infection triggers an immune response in the body that then develops into CFS. The condition has been linked to several viruses, including Epstein-Barr virus (EBV), human herpes virus-6, enteroviruses and echoviruses. While it may seem surprising that many different infectious agents can cause CFS, the reason for this is thought to lie in the body’s remarkably uniform response to assaults by different agents. This means that any number of viruses may be capable of initiating the syndrome.

There is already evidence that viral infections lead to an increase in CFS cases. A study of EBV, Q fever and Ross River virus found that, 6 months after clearing their initial infection, around 12% of participants still met the criteria for a diagnosis of CFS. Previous coronavirus outbreaks have also resulted in documented cases of CFS. In both the recent SARS and MERS outbreaks, long-lasting symptoms were frequently reported by patients. Nearly a quarter of SARS survivors still meet CFS criteria years after their initial infection. Preliminary reports suggest that a similar proportion of COVID-19 patients will suffer the same fate.

The impact of long COVID on the workplace is still unclear. The All-Party Parliamentary Group on Coronavirus are calling for the condition to be recognised as an occupational disease, and it is likely that many organisations will suffer some degree of long-term absenteeism due to it. The broad spread and fluctuating nature of symptoms may increase the difficulty of both recognising genuine cases and managing employees’ return to work. Most cases will need to be approached on an individual basis, rather than through a more usual phased return. Thus, existing sickness and absenteeism policies may not be suitable for managing employees with long COVID and may need to be rethought, as a failure to acknowledge or adequately support employees with the condition could leave organisations open to legal proceedings.

Current evidence suggests that, for a proportion of patients, COVID-19 becomes a chronic condition, presenting similar symptoms to those of CFS. In fact, many COVID patients who have gone on to develop chronic symptoms have learned how to manage their condition by drawing on the experiences of CFS sufferers. Historically, the management of conditions with poorly-defined symptoms or uncertain diagnoses has been perceived as less important and given a lower priority. The emergence of long COVID may lead to an improvement in the general understanding of the long-term consequences of viral infections, including conditions such as CFS, and a wider acceptance of these conditions within the medical profession. This in turn may lead to increased funding into research, which is urgently required to give a better understanding of how symptoms develop and can be managed.

About Dr Jenner

A Consultant in Pain Medicine, Dr Christopher Jenner MB BS, FRCA FFPMRCA has expertise in treating a variety of painful conditions.

As a leader in his field, Dr Jenner is well-known as an experienced and skilled expert witness in a wide range of medicolegal cases involving pain. He has been an expert witness for 15 years and his instructions are broadly divided as claimant (55%), defendant (40%) Single Joint Expert (5%). He provides reports for both medical negligence and personal injury claims.

His particular areas of expertise include, but are not limited to:

  • Neuropathic pain
  • Chronic and chronic widespread pain
  • Chronic Pain Syndromes
  • Complex Regional Pain Syndrome
  • Phantom limb pain and Post Mastectomy Pain Syndrome
  • Multi-disciplinary pain management
  • Fibromyalgia

Read his full biography and download his CV here.

Further reading:

Read further Q and A with Dr Jenner on this subject here.

Long COVID – we’ve been here before. (n.d.). Retrieved April 8, 2021, from

Wildwing T, Holt N. The neurological symptoms of COVID-19: a systematic overview of systematic reviews, comparison with other neurological conditions and implications for healthcare services. Ther Adv Chronic Dis. 2021 Jan 28;12:2040622320976979. doi: 10.1177/2040622320976979. PMID: 33796241; PMCID: PMC7970685.