Understanding Post-Viral Fatigue Syndrome

By December 9, 2022Uncategorized

Most people who contract COVID-19 recover fully within a couple of weeks. However, a minority experience long-term symptoms for weeks or even months after the acute infection. Known as “long Covid,” these patients may suffer from debilitating fatigue, headaches, muscle pain, brain fog, and depression and anxiety (5). As many as ten percent of those who are infected by SARS-CoV-2 will experience lingering symptoms by some estimates (5). However, the phenomenon of long-term, systemic illness following viral infections is not new. High incidences of similar illnesses have been recorded following infectious outbreaks throughout the twentieth century (5). These conditions can collectively be studied as post-viral fatigue syndrome. 

For instance, after the 2003 outbreak of SARS-CoV-1, 60% of patients were still experiencing fatigue at twelve months (5). And during the 1918 H1N1 influenza pandemic, many of those affected experienced long-term, neurological disorders (3). For some, post-viral fatigue syndrome progressed to a debilitating neuroinflammatory illness known as Chronic Fatigue Syndrome (2). Patients’ calls for increased research and support around these chronic conditions have often been dismissed or discredited by medical professionals. Now, new findings surrounding long Covid may offer evidence to bolster research and treatment for post-viral fatigue syndrome. 

Post-viral fatigue syndrome is defined as a multi-systemic, complex condition that is caused by an acute or chronic viral infection (4). Patients experience various physical, cognitive, and neurological disabilities that may severely impact their ability to function in daily life. Viruses that can trigger post-viral fatigue syndrome include Epstein-Barr virus, influenza, Zika virus, Ebola, and Lyme disease (3). These viruses may also be responsible for other chronic diseases. For instance, strong evidence suggests that Epstein-Barr virus can cause Multiple Sclerosis (M.S.), an autoimmune disorder in which the immune system attacks the myelin sheath around nerves (7). 

In some cases, the severity and duration of symptoms may evolve into a condition called Myalgic Encephalomyelitis or Chronic Fatigue Syndrome (ME/CFS). ME/CFS patients suffer from severe fatigue that does not improve with sleep, worsening of symptoms after physical or mental exertion, insomnia, exercise intolerance, and digestive, immune, and cognitive issues (2). Despite the severity of the condition, ME/CFS remains one of the illnesses that is most underfunded for research compared to disease burden (2). In part, this may be because 75 to 85 percent of ME/CFS patients are women, and illnesses that primarily impact women have been historically overlooked (2).  

Researchers at the Yale School of Medicine recently launched the Yale LISTEN Study in response to growing public interest in long Covid. The study aims to “learn more about long COVID, post-vaccine adverse events, and the corresponding immune responses” to illuminate some of the causes, symptoms, and effective treatments for poorly understood, chronic illnesses (2). Professors Akiko Iwasaki and Harlan Krumholz, who are leading the study, hypothesize several different causes that could be responsible for long Covid and other types of post-viral fatigue syndrome. For instance, the acute infection may trigger an autoimmune response or create an imbalance of bacteria in the gut microbiome (2). Another possibility is that irreparable tissue damage occurs during the acute infection, leading to long-term symptoms (2). 

Nevertheless, in order to better understand post-viral fatigue syndrome, a more holistic approach for management and treatment needs to be developed. Collaboration between multidisciplinary teams of doctors is necessary to treat this complex condition, and treatment should strive to improve quality of life for patients through both pharmacological and non-pharmacological methods (5). Moreover, increased funding for studying ME/CFS and other related conditions is necessary to develop treatments for these long-standing yet still poorly understood illnesses that cause great human suffering. 



  1. Astin, Rónan et al. “Long COVID: mechanisms, risk factors and recovery.” Experimental Physiology, 2022, pp. 1-16, doi:10.1113/EP090802 
  2. Backman, Isabella. “Will Long COVID Research Provide Answers for Poorly Understood Diseases Like ME/CFS?” Yale School of Medicine, 01 Nov 2022, medicine.yale.edu/news-article/will-long-covid-research-provide-answers-for-poorly-understood-ailments-like-chronic-fatigue/ 
  3. Balfour, Hank and William Hoffman. “It’s Not Just Long COVID.” The Atlantic, 12 Aug 2022., www.theatlantic.com/ideas/archive/2022/08/long-covid-monovirus-ebv/671080/ 
  4. Kopf, Michael. “Post-viral Fatigue Syndrome: Symptoms & Treatment.” K Health, 11 April 2022, khealth.com/learn/fatigue/post-viral-fatigue-syndrome/ 
  5. Pintos-Pascual, Ilduara, et al. “Is SARS-CoV-2 the only cause of long-COVID?” Aids reviews, 25 Nov 2022, doi:10.24875/AIDSRev.22000025 
  6. “Post-viral fatigue: a guide to management.” North Bristol NHS Trust, The British Associations of Clinicians in ME/CFS, n.d., www.nbt.nhs.uk/our-services/a-z-services/bristol-me-service/post-viral-fatigue-a-guide-management/ 
  7. Tingley, Kim. “The Strange Connection Between Mono and M.S.” The New York Times Magazine, 7 March 2022, www.nytimes.com/2022/02/23/magazine/epstein-barr-virus-multiple-sclerosis.html