Long Covid is a new name for an old syndrome

Long Covid goes by many names. Today, it is no longer a new public health enigma, but the outlook for sufferers is no better than when the condition was first recognized in early 2020. Although its prevalence has recently decreased to 6% of the U.S. adult population, there has been no significant progress in understanding its causes, prevention, or treatment. Long Covid still looms as the national health disaster many predicted. Everyone — patients, support groups, clinicians, researchers, and health care systems — is frustrated by lack of meaningful progress in research and patient care.

On the research side, the U.S. government rapidly anticipated and tried to blunt the force of this national calamity by investing in basic and clinical research. Hopes were raised in December 2020 when Congress provided $1.15 billion over four years to the NIH to launch its long Covid research initiative called RECOVER. The Centers for Disease Control and Prevention additionally initiated its Innovative Support for Patients with Covid-19 Infections Registry (INSPIRE). Veterans Affairs also deployed the nation’s largest health care system in support of LC research.

Now, more than two years down this ambitious path, and with published results emerging, outraged experts and patient advocates say that there is “little to show for it.” The critique is that mostly observational studies have characterized risk factors, demographics, and attributes of the clinical syndrome, but little has emerged that directly contributes to prevention or patient care.

The view from the patient care side is no more optimistic. People with long Covid are subject to stigmatization and feel disempowered as they navigate a fragmented health care system not organized to deliver patient-centric care.

While long Covid’s causes and treatments remain elusive, its health, social, and economic toll is enormous and indisputable. A 2022 paper projected the total U.S. economic impact in quality of life, lost earnings, and medical care spending at $3.7 trillion. That’s $11,000 per capita or 17% of the 2019 gross domestic product. As the country has largely moved on from the acute phase of the pandemic, long Covid has left a trail of frustration, suffering, functional impairment, and disability.

The current grim reality is underscored by the unsatisfying National Institutes of Health guidance that “the best way to prevent long COVID is to avoid getting COVID-19.” Although true, this advice offers scant comfort to the large majority of Americans who have been infected by Covid-19 and to most who are still at risk for new or re-infections — especially now, when there are few societal efforts to prevent transmission.

The solution for this seemingly unsolvable puzzle is hiding in plain sight. Long Covid is a new term coined for an old syndrome that has long bedeviled the ecosystem of clinicians, researchers, patients, support groups, and health care systems. It’s a unifying hypothesis that explains most observed facts around the striking lack of inroads against long Covid.

Long Covid is really not new. It is virtually indistinguishable from the condition long known in the medical lexicon as post-infectious syndrome or myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Although some have recognized and studied their similarities, it seems no one has made the simplifying observation that they are essentially the same condition.

In the ME/CFS paradigm, long Covid is not a new condition. Logic and reason dictate that acute SARS-CoV-2 infection causes long Covid.

Or, more accurately, acute Covid-19 triggers ME/CFS in the same way many other infectious agents trigger ME/CFS. “Triggers” means a temporal association, but not “cause” in a mechanistic sense — at least not identifiable with currently available scientific tools. This hypothesis has major policy, research, and patient-care best practice implications. It’s our most direct path forward to reset society’s goals, strategies, and expectations for true progress against this public health catastrophe.

Although much about ME/CFS is still not well-understood, decades of experience and research into this condition could be productively and rapidly applied to long Covid. That approach could help avoid missteps, focus investment priorities, ground societal expectations regarding what is achievable, and improve patient welfare dramatically.

For example, basic research has focused on identifying long Covid laboratory markers and the pathogenesis (mechanism) linking the virus with the symptoms. Researchers are exploring biologically plausible hypotheses including viral persistence, microvascular clots, gut microbiome disruption, and immune system derangements as the mechanism behind long Covid symptoms.

But if long Covid is really a form of ME/CFS, this approach will likely be unrewarding. Decades of ME/CFS research exploring etiology and pathogenesis have been unproductive. The current research directed at finding mechanistic clues to long Covid is a resource-intensive and lengthy uncharted process. It is likely to produce further leads for more research, but with a low ultimate probability of success in helping patients.

There is an already extensive body of patient-care experience, guidance, and resources for best practice to build on in the clinical management of post-infection syndromes. This should be aggressively applied to the benefit of long Covid patients. This approach includes “coordinating clinical care and rehabilitation, reducing health care disparities, and addressing ongoing and complex medical and psychosocial needs.” Patient education and health care workforce training are an essential component in the dissemination of best practices and in setting realistic expectations for prognosis and treatment outcomes. The wheel does not need to be reinvented, only improved. A current consensus long Covid definition is that it is a disorder following acute Covid-19 infection “with symptoms not attributable to any other condition.” It can present with a myriad of more than 200 symptoms referable to any organ system. This is virtually identical to the Institute of Medicine’s 2015 case definition of ME/CFS.

For the sake of definitional clarity, there are a few well-documented consequences of acute Covid-19 that are caused by the SARS-CoV-2 virus. These are MIS-C, myocarditis, and blood clots. Where there are clear objective signs of disease that are diagnosable outside the patient, the illness is excluded from the ME/CFS paradigm. Another exclusion is the post-intensive care syndrome (PICS). According to the CDC, “people experiencing any severe illness, hospitalization, or treatment may develop problems such as PICS. For people who experience PICS following a COVID-19 diagnosis, it is difficult to determine whether these health problems are caused by a severe illness, the virus itself, or a combination of both.”

Conditions similar to ME/CFS have been described in the medical literature for centuries. Although well-described symptom clusters similar to ME/CFS were reported as early as the 1930s, the term myalgic encephalomyelitis was first used to describe the condition in the 1950s, and ME was recognized by the World Health Organization as a disease entity in the 1960s. The term chronic fatigue syndrome was coined in the 1980s for cases simulating post-viral syndromes that were not found to have a viral etiology. In this unifying framework, fibromyalgia and postural orthostatic tachycardia syndrome (POTS) — other debilitating symptom clusters — are included as subsets of CFS.

Just as there was with ME/CFS, there is an ongoing, polarizing debate of whether long Covid is “real,” as in an organic disease with presumed identifiable physical or biochemical signs, or an “imagined” non-organic disorder with no discernible cause. However this is a false dichotomy. Scientific evidence shows that post-infectious fatigue syndromes (including long Covid) can have a spectrum of inseparable pathobiological and psychological components. Acknowledging this is culturally unifying and will generate more light than heat in helping chart society’s path forward. It allows for less contentious, more productive, and targeted patient care and research strategies; enlightened policies; and more cost-effective investments for addressing the long Covid crisis.

The enormous global toll of Covid-19-associated post-infectious syndrome is readily explained in the conventional epidemiologic paradigm. SARS-CoV-2 and its variants are among the most communicable human viruses in history and with extensive international movement, infected the vast majority of the initially completely immunologically-naive people on the planet. The broad range of the observed 7.5% to 41% of post-acute Covid symptoms is consistent with general post-viral CFS rates. As the virus keeps circulating, natural and vaccination-related population immunity continues to build, the gradual diminishing of CFS incidence is to be expected. This is the recent pattern we have observed in the U.S. With Covid-19 endemicity, an ongoing decrease in CFS rates is likely.

The recognition that long Covid is the latest emergence of an old syndrome and not a de novo new entity, while no panacea, augurs a fundamental reset of every aspect of societal response. It reframes but does not change the facts. It provides the foundation for better strategies and manages expectations around what is likely and unlikely to work in prevention, treatment, research and policy. It prioritizes care delivery over research in the expenditure of government funds.

A recent editorial has recommended that Congress fund the Health Resources and Services Administration to “competitively select centers of excellence in long COVID patient care … that were established as part of the RECOVER initiative.” A now vastly expanded and refocused effort on patient care for ME/CFS could help build bridges of understanding, collaboration, and empathy across the diverse constituencies of the long Covid ecosystem. It could serve as a more productive and accurate new paradigm for how we as a society face the challenge of long Covid.

Steven Phillips, M.D., M.P.H., is a Global Virus Network board member and vice president for science and strategy at the COVID Collaborative. Michelle A. Williams, Sc.D., is the former dean and is the Joan and Julius Jacobson professor of epidemiology and public health at the Harvard T.H. Chan School of Public Health.