Long COVID

As many in the ME/CFS community know, infection-associated chronic illness is not new. While ME/CFS can be triggered by a variety of factors, in up to 80% of cases that initiating factor is a viral illness.

Long COVID, also known as post-acute sequelae of SARS-CoV-2 infection (PASC), is the complex and lingering illness that persists at least three months after a COVID infection and affects one or more organ systems. Symptoms range widely, can vary from mild to severe, and may relapse and recur [1]. Long COVID can also involve many other diagnosable conditions, including postural orthostatic tachycardia syndrome (POTS) and other dysautonomias, blood clots, and mast cell activation syndrome (MCAS). A significant number (50% or more) of Long COVID patients have symptoms consistent with ME/CFS.

Research continues into the causes and potential treatments for Long COVID. Currently, many of the clinical care recommendations parallel those for ME/CFS – see our Resources for Providers and Lessons Learned from ME/CFS sections.

Long COVID and Other IACCIs

The COVID-19 pandemic has made the world aware that infectious agents, such as the coronavirus, can cause chronic conditions in a subset of individuals. Long COVID is now recognized to be only one of many different Infection-Associated Chronic Conditions and Illnesses (IACCIs).

IACCIs are complex disorders that involve multiple organ systems and are associated with an infectious etiology (i.e. a viral, fungal, or bacterial infection). These disorders include myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), dysautonomia/postural orthostatic tachycardia syndrome (POTS), fibromyalgia, post-treatment Lyme disease (PTLD), mast cell activation syndrome (MCAS), and Long COVID/Post-Acute Sequela of COVID-19 (PASC). IACCIs cause an enormous level of disability. Affected people may not be able to work, attend school, or even engage in daily self-care activities. In severe cases, quality of life is dramatically impacted, causing a lifetime of disability.

Illness	Prevalence in Adults
Long COVID/PASC	24-56 million
ME/CFS*	4-9 million
Fibromyalgia*	4 million
POTS*	3 million
PTLD	1 million

Table 1: List of common IACCIs in order of decreasing prevalence as of 2023.
*Asterisked illnesses are co-morbid with Long COVID/PASC.

Millions of Americans are estimated to have IACCIs (Table 1). Prevalence has increased rapidly since the COVID-19 pandemic. In 2022, Long COVID/PASC impacted 24 million adults (6.8% of Americans) and up to 4 million people (15% of the labor force) were newly out of work due to illness [2, 3]. By early 2024 incidence had risen to 56 million (17.6%) [2]. Of the people impacted by Long COVID, 50% also met diagnostic criteria for ME/CFS and up to 80% were estimated to have POTS [4, 5].

Despite the burden of disease and the economic impact on the labor workforce, IACCIs are still highly under-researched and poorly understood by the medical community. There are no clinically standardized biomarkers, diagnostic tests, or treatment protocols for these illnesses. IACCIs are multi-systemic illnesses and require a holistic approach. The medical community, however, is highly fragmented by specialization, and IACCIs do not fit neatly into any single specialty. Hopefully, research and medical organizations dedicated to IACCIs will arise, as Americans start understanding the need behind these disorders.

References

National Academies of Science, Engineering, and Medicine. A Long COVID Definition: A Chronic, Systemic Disease State with Profound Consequences. The National Academies Press, 2024.
Centers for Disease Control and Prevention. (2024, March 21). Long Covid – Household Pulse survey – covid-19. Centers for Disease Control and Prevention, March 21, 2024. https://www.cdc.gov/nchs/covid19/pulse/long-covid.htm
Bach, K. “New data shows long covid is keeping as many as 4 million people out of work.” Brookings Institute, August 24, 2022. https://www.brookings.edu/articles/new-data-shows-long-covid-is-keeping-as-many-as-4-million-people-out-of-work/
Davis, H. E., et al. “Long Covid: Major findings, mechanisms and recommendations,” Nature Reviews Microbiology, 21(3), 133–146.
Seeley, M.-C., et al. “High incidence of autonomic dysfunction and postural orthostatic tachycardia syndrome in patients with long COVID: Implications for management and health care planning,”: The American Journal of Medicine 138, no.2: 354-361 .

Resources

In 2024 the National Academies of Science, Engineering, and Medicine produced a detailed definition of Long COVID. The report involved significant patient involvement.
SolveME has an excellent selection of resources for people with Long COVID.
Ed Yong’s essays in The Atlantic covered the gradual recognition of Long COVID and its devastating consequences.

- “Long COVID Has Forced a Reckoning for One of Medicine’s Most Neglected Diseases” (PDF) (September 2022) Only a couple dozen doctors specialize in chronic fatigue syndrome (ME/CFS). Now their knowledge could be crucial to treating millions more patients.
- “One of Long COVID’s Worst Symptoms Is Also Its Most Misunderstood” (PDF) (about brain fog; September 2022)
- “Fatigue Can Shatter a Person” (PDF) (July 2023) Everyday tiredness is nothing like the depleted symptom that people with long COVID and ME/CFS experience.