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Trying to Make Sense of Long COVID Syndrome

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Credit: NIH

More than 400,000 Americans have now lost their lives to COVID-19. But thousands of others who’ve gotten sick and survived COVID-19 are finding that a full recovery can be surprisingly elusive. Weeks and months after seemingly recovering from even mild cases of COVID-19, many battle a wide range of health problems.

Indeed, new results from the largest global study of this emerging “Long COVID syndrome” highlight just how real and pressing this public health concern really is. The study, reported recently as a pre-print on medRxiv, is based on survey results from more than 3,700 self-described COVID “Long Haulers” in 56 countries [1]. They show nearly half couldn’t work full time six months after unexpectedly developing prolonged symptoms of COVID-19. A small percentage of respondents, thankfully, seemed to have bounced back from brief bouts of Long COVID, though time will tell whether they have fully recovered.

These findings are the second installment from the online Body Politic COVID-19 Support Group and its Patient-Led Research for COVID-19, which consists of citizen scientists with a wide range of expertise in the arts and sciences who are struggling with the prolonged effects of COVID-19 themselves. In an earlier survey, this group provided a first-draft description of Long COVID syndrome, based on the self-reported experiences of 640 respondents.

In the new survey-based study led by Athena Akrami, with Patient-Led Research for COVID-19 and University College London, England, the goal was to characterize the experiences of many more people with Long COVID syndrome. They now define the syndrome as a collection of symptoms lasting for more than 28 days.

This second survey emphasizes the course and severity of more than 200 symptoms over time, including those affecting the heart, lungs, gastrointestinal system, muscles, and joints. It took a particularly in-depth look at neurological and neuropsychiatric symptoms, along with the ability of COVID-19 survivors to return to work and participate in other aspects of everyday life.

The 3,762 individuals who responded to the survey were predominately white females, between the ages of 30 and 60, who lived in the United States. As in the previous survey, the study included adults with symptoms consistent with COVID-19, whether or not the infection had been confirmed by a viral or antibody test. That is a potential weakness of the study, as some of these individuals may have had some other inciting illness. But many of the study’s participants developed symptoms early on in the pandemic, when testing was much more limited than it is now.

More than half never sought hospital care. Only 8 percent said that they’d been admitted to the hospital for COVID-19. And yet, 2,464 respondents reported COVID-19 symptoms lasting six months or longer. Most of the remaining respondents also continued to have symptoms, although they had not yet reached the six-month mark.

Among the most common symptoms were fatigue, worsening of symptoms after physical or mental activity, shortness of breath, trouble sleeping, and “brain fog,” or difficulty thinking clearly. The majority—88 percent—said they coped with some form of cognitive dysfunction or memory loss that to varying degrees affected their everyday lives. That includes the ability to make decisions, have conversations, follow instructions, and drive.

Those who had prolonged symptoms of COVID-19 for more than six months reported contending with about 14 symptoms on average. Most also reported that they’d had a relapse of symptoms, seemingly triggered by exercise, mental activity, or just everyday stress. When surveyed, nearly half of respondents said they’d had to reduce their hours at work due to the severity of their symptoms. Another 22 percent weren’t working at all due to their Long COVID.

The findings show that—even in those people who don’t require hospitalization for severe COVID-19—the condition’s prolonged symptoms are having a major impact on lives and livelihoods, both here and around the world. While the number of people affected isn’t yet known, if even a small proportion of the vast numbers of people infected with COVID-19 develop Long COVID syndrome, it represents a significant public health concern.

Another recent study from China further documents the tendency of COVID-19-related symptoms to linger past the usual recovery time for a respiratory virus [2]. The study, published in Lancet, showed that six months after the onset of illness, more than 75 percent of people hospitalized with COVID-19 in Wuhan between January and May 2020 continued to report at least one symptom. Fatigue, muscle weakness, sleep difficulties, anxiety, and depression all were common. More than half of individuals also had significant persistent lung abnormalities, which were more common in those who’d been more severely ill.

It’s essential for us to learn all we can about how SARS-CoV-2, which is the coronavirus that causes COVID-19, leads to such widespread symptoms. It’s also essential that we develop ways to better treat or prevent these symptoms. The NIH held a workshop last month to summarize what is known and fill in key gaps in our knowledge about Long COVID syndrome, which is clinically known as post-acute sequelae of COVID-19 (PASC). In December, Congress authorized funding for continued research on PASC, including an appropriation of funds for NIH to support continued study of these prolonged health consequences.

As these efforts and others proceed in the coming months, the hope is that we’ll gain much more insight and get some answers soon. And, if you’ve had or are currently experiencing symptoms of COVID-19, there’s still time to share your data by participating in the Patient-Led Research for COVID-19’s second survey.

References:

[1] Characterizing Long COVID in an international cohort: 7 months of symptoms and their impact. David HE et al. Medrxiv. 27 December 27 2020.

[2] 6-month consequences of COVID-19 in patients discharged from hospital: a cohort study. Huang C, Huang L, et al. Lancet. 2021 Jan 16;397(10270):220-232.

Links:

COVID-19 Research (NIH)

Akrami Lab (Sainsbury Wellcome Center, University College London, England)

Patient-led Research for COVID-19

Video: Workshop on Post-Acute Sequelae of COVID-19 (NIH)


Taking a Closer Look at COVID-19’s Effects on the Brain

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MRI of a brain damaged by COVID-19
Caption: Magnetic resonance microscopy showing lower part of a COVID-19 patient’s brain stem postmortem. Arrows point to light and dark spots indicative of blood vessel damage with no signs of infection by the coronavirus that causes COVID-19. Credit: National Institute of Neurological Disorders and Stroke, NIH

While primarily a respiratory disease, COVID-19 can also lead to neurological problems. The first of these symptoms might be the loss of smell and taste, while some people also may later battle headaches, debilitating fatigue, and trouble thinking clearly, sometimes referred to as “brain fog.” All of these symptoms have researchers wondering how exactly the coronavirus that causes COVID-19, SARS-CoV-2, affects the human brain.

In search of clues, researchers at NIH’s National Institute of Neurological Disorders and Stroke (NINDS) have now conducted the first in-depth examinations of human brain tissue samples from people who died after contracting COVID-19. Their findings, published in the New England Journal of Medicine, suggest that COVID-19’s many neurological symptoms are likely explained by the body’s widespread inflammatory response to infection and associated blood vessel injury—not by infection of the brain tissue itself [1].

The NIH team, led by Avindra Nath, used a high-powered magnetic resonance imaging (MRI) scanner (up to 10 times as sensitive as a typical MRI) to examine postmortem brain tissue from 19 patients. They ranged in age from 5 to 73, and some had preexisting conditions, such as diabetes, obesity, and cardiovascular disease.
The team focused on the brain’s olfactory bulb that controls our ability to smell and the brainstem, which regulates breathing and heart rate. Based on earlier evidence, both areas are thought to be highly susceptible to COVID-19.

Indeed, the MRI images revealed in both regions an unusual number of bright spots, a sign of inflammation. They also showed dark spots, which indicate bleeding. A closer look at the bright spots showed that tiny blood vessels in those areas were thinner than normal and, in some cases, leaked blood proteins into the brain. This leakage appeared to trigger an immune reaction that included T cells from the blood and the brain’s scavenging microglia. The dark spots showed a different pattern, with leaky vessels and clots but no evidence of an immune reaction.

While those findings are certainly interesting, perhaps equally noteworthy is what Nath and colleagues didn’t see in those samples. They could find no evidence in the brain tissue samples that SARS-CoV-2 had invaded the brain tissue. In fact, several methods to detect genetic material or proteins from the virus all turned up empty.

The findings are especially intriguing because there has been some suggestion based on studies in mice that SARS-CoV-2 might cross the blood-brain barrier and invade the brain. Indeed, a recent report by NIH-funded researchers in Nature Neuroscience showed that the viral spike protein, when injected into mice, readily entered the brain along with many other organs [2].

Another recent report in the Journal of Experimental Medicine, which used mouse and human brain tissue, suggests that SARS-CoV-2 may indeed directly infect the central nervous system, including the brain [3]. In autopsies of three people who died from complications of COVID-19, the NIH-supported researchers detected signs of SARS-CoV-2 in neurons in the brain’s cerebral cortex. This work was done using the microscopy-based technique of immunohistochemistry, which uses antibodies to bind to a target, in this case, the virus’s spike protein. Also last month, in a study published in the journal Neurobiology of Disease, another NIH-supported team demonstrated in a series of experiments in cell culture that the SARS-CoV-2 spike protein could cross a 3D model of the blood-brain barrier and infect the endothelial cells that line blood vessels in the brain [4].

Clearly, more research is needed, and NIH’s National Institute of Neurological Disorders and Stroke has just launched the COVID-19 Neuro Databank/Biobank (NeuroCOVID) to collect more clinical information, primarily about COVID-19-related neurological symptoms, complications, and outcomes. Meanwhile, Nath and colleagues continue to explore how COVID-19 affects the brain and triggers the neurological symptoms often seen in people with COVID-19. As we learn more about the many ways COVID-19 wreaks havoc on the body, understanding the neurological symptoms will be critical in helping people, including the so-called Long Haulers bounce back from this terrible viral infection.

References:

[1] Microvascular Injury in the Brains of Patients with Covid-19. Lee MH, Perl DP, Nair G, Li W, Maric D, Murray H, Dodd SJ, Koretsky AP, Watts JA, Cheung V, Masliah E, Horkayne-Szakaly I, Jones R, Stram MN, Moncur J, Hefti M, Folkerth RD, Nath A. N Engl J Med. 2020 Dec 30.

[2] The S1 protein of SARS-CoV-2 crosses the blood-brain barrier in mice. Rhea EM, Logsdon AF, Hansen KM, Williams LM, Reed MJ, Baumann KK, Holden SJ, Raber J, Banks WA, Erickson MA. Nat Neurosci. 2020 Dec 16.

[3] Neuroinvasion of SARS-CoV-2 in human and mouse brain. Song E, Zhang C, Israelow B, et al. J Exp Med (2021) 218 (3): e20202135.

[4] The SARS-CoV-2 spike protein alters barrier function in 2D static and 3D microfluidic in-vitro models of the human blood-brain barrier. Buzhdygan TP, DeOre BJ, Baldwin-Leclair A, Bullock TA, McGary HM, Khan JA, Razmpour R, Hale JF, Galie PA, Potula R, Andrews AM, Ramirez SH. Neurobiol Dis. 2020 Dec;146:105131.

Links:

COVID-19 Research (NIH)

Avindra Nath (National Institute of Neurological Disorders and Stroke/NIH)

NIH Support: National Institute of Neurological Disorders and Stroke; National Institute on Aging; National Institute of General Medical Sciences; National Cancer Institute; National Institute of Mental Health