Long COVID in Context: Prevalence, Search Interest, and Funding
By Gregory Kirchhoff
The exact risk of developing Long COVID after a SARS-CoV-2 infection remains difficult to quantify. Research on the condition is still relatively young, as COVID-19 emerged only five years ago. In addition, Long COVID presents with a remarkably diverse range of symptoms, severities, and timing of when various symptoms onset, and so there is still no stable universally accepted clinical definition.
Different diagnostic thresholds therefore yield different estimates of prevalence, the number of people currently living with a condition. More restrictive definitions that capture only the most debilitating cases inevitably exclude many individuals who are still experiencing meaningful health impacts. In contrast, more sensitive criteria encompass a broader portion of those affected, including people with persistent but non-disabling symptoms, or even individuals with measurable physiological changes who don’t perceive any changes in their wellbeing.
Regardless of how one chooses to define Long COVID, the condition is undeniably common. According to the Rare Diseases Act of 2002, a disease is defined as “rare” if it affects fewer than 200,000 Americans [1]. That means that a disease must affect less than 0.059% of the American population to be considered rare [2]. By contrast, the CDC’s Household Pulse Survey estimates that 5.3% of U.S. adults currently have Long COVID, making it about 90 times more common than the threshold for rarity and placing its prevalence in the same range as major chronic conditions such as heart disease [3][4]. Even more concerning is that some studies report substantially higher rates, such as one reporting 36% of the global population being affected [5]. This represents a range of around 14 to 96 million affected U.S. adults [6]. Long COVID is already estimated to be the most common chronic illness in children, with almost 6 million U.S. children potentially affected [7]. Use the dropdown menu above the following graph to view the relative prevalence of Long COVID compared to more well-known diseases and to the rare disease threshold using different studies’ estimates of Long COVID cases.
The high prevalence of this condition necessitates strong societal and governmental responses in order to combat spread of COVID-19 and the associated increase in Long COVID cases, as well as to fund research into treatments for those impacted. However, both public interest and government funding are sorely lacking [8], especially when taking into consideration the prevalence of those impacted.
In order to see how under-funded an illness is, view prevalence as a ratio of funding. The bar will be at its highest for illnesses that impact disproportionately many people compared to the funding that it receives.
So why is funding and interest in Long COVID so lacking? The funding makes it seem that Long COVID is rare or mild, despite evidence to the contrary: multiple mechanisms underlying long-term damage from infection have already been documented [9] and economic impacts are being felt, personally and across society [10]. One potential reason Long COVID is underestimated is that SARS-CoV-2 can affect nearly every organ system, which means that two individuals with Long COVID may experience completely different sets of symptoms, which makes it difficult to perceive that there is a single cause behind many new, seemingly unrelated illnesses. In addition, many of the symptoms, such as fatigue and hairloss, can be misattributed to other sources. This variability makes it difficult for patients, clinicians, and policymakers to recognize new or worsening health issues as sequelae of a prior infection. Adding to the confusion, symptoms often emerge only weeks or even months after the initial illness, obscuring the connection further [11]. Perhaps psychological factors are another major reason society has yet to confront the dire reality of Long COVID. Stigma and medical gaslighting remain common, discouraging reporting and undermining public understanding of the disease [12]. Many classic psychological defense mechanisms also likely play a role such as denial, rationalization, and intellectualization.
What should be obvious at this point is that we should care. The damage caused by SARS-CoV-2 has been profound, yet it is still widely circulating and continues to cause harm. Moreso, with all said about the mechanisms of long-term damage from SARS-CoV-2 infections, COVID-19 is still a new disease. At year 5 of the pandemic, we are still well within the latency period of many chronic conditions, and there are no studies that assess how COVID-19 impacts the body beyond 5 years. There is growing evidence of viral persistence as a possible mechanism of Long COVID, which acts as another reason to treat infection as non-trivial [13].
The good news is that action, at the individual and societal level, is worth it. COVID-19 can be prevented. Well-fitting N95 and higher respirators are highly effective at protecting yourself and others from infection [14]. Clean air technology shows promise in mitigating transmission in community hotspots such as schools and hospitals, while also coming with secondary benefits such as allergy and other disease mitigation [15]. It is of utmost importance that we utilize the tools we have to prevent any increases to our already enormous burden of Long COVID and demand action from our governments to fund research into treatments for the many who need it, but are unable to fight for themselves.
References:
[1] govinfo.gov/content/pkg/PLAW-107publ280/html/PLAW-107publ280.htm
[2] National Population Totals: 2020-2024
[3] Long COVID – Household Pulse Survey – COVID-19
[4] BRFSS Prevalence & Trends Data: Home | DPH | CDC
[8] R&D for long COVID is collapsing
[9] The immunology of long COVID | Nature Reviews Immunology
[11] Long Covid in Aotearoa NZ: Risk assessment and preventive action urgently needed | PHCC
[15] Taking Steps for Cleaner Air for Respiratory Virus Prevention | Respiratory Illnesses | CDC
