Long COVID or Post-acute Sequelae of COVID-19 (PASC): An Overview of Biological Factors That May Contribute to Persistent Symptoms

Abstract:

The novel virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a pandemic of coronavirus disease 2019 (COVID-19). Across the globe, a subset of patients who sustain an acute SARS-CoV-2 infection are developing a wide range of persistent symptoms that do not resolve over the course of many months. These patients are being given the diagnosis Long COVID or Post-acute sequelae of COVID-19 (PASC). It is likely that individual patients with a PASC diagnosis have different underlying biological factors driving their symptoms, none of which are mutually exclusive.

This paper details mechanisms by which RNA viruses beyond just SARS-CoV-2 have be connected to long-term health consequences. It also reviews literature on acute COVID-19 and other virus-initiated chronic syndromes such as post-Ebola syndrome or myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) to discuss different scenarios for PASC symptom development. Potential contributors to PASC symptoms include consequences from acute SARS-CoV-2 injury to one or multiple organs, persistent reservoirs of SARS-CoV-2 in certain tissues, re-activation of neurotrophic pathogens such as herpesviruses under conditions of COVID-19 immune dysregulation, SARS-CoV-2 interactions with host microbiome/virome communities, clotting/coagulation issues, dysfunctional brainstem/vagus nerve signaling, ongoing activity of primed immune cells, and autoimmunity due to molecular mimicry between pathogen and host proteins. The individualized nature of PASC symptoms suggests that different therapeutic approaches may be required to best manage care for specific patients with the diagnosis

Source: Proal AD, VanElzakker MB. Long COVID or Post-acute Sequelae of COVID-19 (PASC): An Overview of Biological Factors That May Contribute to Persistent Symptoms. Front Microbiol. 2021 Jun 23;12:698169. doi: 10.3389/fmicb.2021.698169. PMID: 34248921; PMCID: PMC8260991. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8260991/ (Full study)

Assessment of Prolonged Physiological and Behavioral Changes Associated With COVID-19 Infection

Introduction: Long-term COVID symptoms marked by autonomic dysfunction1 and cardiac damage2 following COVID-19 infection have been noted for up to 6 months after symptom onset,3 but to date have not been quantified, to our knowledge. Previous studies have found that wearable data can improve real-time detection of viral illness4 or discrimination of individuals with COVID-19 vs other viral infections.5 Wearable devices provide a way to continuously track an individual’s physiological and behavioral metrics beginning when healthy (ie, before infection), during the course of infection, and recovery back to baseline. In this cohort study, we aimed to examine the duration and variation of recovery among COVID-19–positive vs COVID-19–negative participants.
Methods: DETECT (Digital Engagement and Tracking for Early Control and Treatment) is a remote, app-based, longitudinal research study enrolling adult participants from all over the US and collecting their wearable data to better understand individual changes associated with viral illness, including COVID-19. All participants provided informed consent electronically. The protocol for this study was reviewed and approved by the Scripps Office for the Protection of Research Subjects. This study follows the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline.

From March 25, 2020, through January 24, 2021, 37 146 participants were enrolled. This analysis focuses on 875 individuals who reported symptoms of an acute respiratory illness and underwent swab testing for COVID-19 and were found to be either positive (234 individuals) or negative (641 individuals) (eFigure in the Supplement).

The following calculation was used for resting heart rate (RHR): deviation from baseline = daily RHR − baseline RHR mean. Individuals with COVID-19 were also grouped by their mean RHR deviation from baseline 28 to 56 days after symptom onset (<1, 1-5, or >5 beats per minute).

Data analysis was conducted in SAS statistical software version 9.4 (SAS Institute). Significance was set at P < .05. P values were calculated with 1-way ANOVA (for mean age) or χ2 tests. Additional details about our methods can be found in the eAppendix in the Supplement.

Results: For this analysis, our study population consisted of 234 COVID-19–positive individuals (mean [range] age, 45.3 [18-76] years; 164 women [70.9%]) and 641 COVID-19–negative symptomatic individuals (mean [range] age, 44.7 [19-75] years; 455 women [71.1%]). Individuals with COVID-19 took longer to return to their RHR (Figure, A and B), sleep (Figure, C and D), and activity (Figure, E and F) baselines compared with symptomatic individuals who were COVID-19 negative. This difference was most marked for RHR, with COVID-19–positive individuals initially experiencing a transient bradycardia followed by a prolonged relative tachycardia that did not return to baseline, on average, until 79 days after symptom onset. Step count and sleep quantity returned to baseline sooner than RHR at 32 and 24 days, respectively. During recovery, individuals with COVID-19 experienced different trajectories in the return of their RHR to their normal compared with COVID-19–negative individuals (Figure, B). A small subset of COVID-19–positive participants (32 participants [13.7%]) maintained an RHR more than 5 beats per minute greater than their baseline RHR that did not return to their normal for more than 133 days. During the acute phase of COVID-19, individuals in this group reported higher frequencies of cough (27 participants [84.4%] vs 57 participants [55.3%] in the <1 beat per minute group and 57 participants [57.6%] in the 1-5 beats per minute group), body ache (20 participants [62.5%] vs 42 participants [40.8%] in the <1 beat per minute group and 35 participants [35.4%] in the 1-5 beats per minute group), and shortness of breath (9 participants [28.1%] vs 9 participants [8.7%] in the <1 beat per minute group and 6 participants [6.1%] in the 1-5 beats per minute group) compared with the other groups (Table).
Discussion: To our knowledge, this is the first study to examine longer duration wearable sensor data. We found a prolonged physiological impact of COVID-19 infection, lasting approximately 2 to 3 months, on average, but with substantial intraindividual variability, which may reflect various levels of autonomic nervous system dysfunction or potentially ongoing inflammation. Transient bradycardia has been noted in a case study6 approximately 9 to 15 days after symptom onset, which was also seen in our population. Our data suggest that early symptoms and larger initial RHR response to COVID-19 infection may be associated with the physiological length of recovery from this virus.

Symptom data were collected only during the acute phase of infection, which limited our ability to compare long-term physiological and behavioral changes with long-term symptoms. In the future, with larger sample sizes and more comprehensive participant-reported outcomes, it will be possible to better understand factors associated with interindividualized variability in COVID-19 recovery.

Source: Radin JM, Quer G, Ramos E, et al. Assessment of Prolonged Physiological and Behavioral Changes Associated With COVID-19 Infection. JAMA Netw Open. 2021;4(7):e2115959. doi:10.1001/jamanetworkopen.2021.15959 https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2781687 (Full article)

Post COVID syndrome: a new challenge for medicine

Abstract:

The huge concern raised by SARS-CoV2 pandemic about public health management and social impact is still under debate, particularly because COVID-19 may affect infected people much longer than expected from a typical air-borne viral disease. The scientific community is actually wondering about the etiopathogenesis and clinical development of this “post-COVID” complex symptomatology, very close to symptoms typically observed in chronic fatigue syndrome, so recently named as “post-acute sequelae of COVID-19 (PASC)”. This commentary tries to focus on the most recent news about this issue.

Source: Tirelli U, Taibi R, Chirumbolo S. Post COVID syndrome: a new challenge for medicine. Eur Rev Med Pharmacol Sci. 2021 Jun;25(12):4422-4425. doi: 10.26355/eurrev_202106_26154. PMID: 34227079. https://pubmed.ncbi.nlm.nih.gov/34227079/

Post-Acute COVID-19 Symptoms, a Potential Link with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A 6-Month Survey in a Mexican Cohort

Abstract:

The aim of this study was to describe the clinical evolution during 6 months of follow-up of adults recovered from COVID-19. We tried to determine how many met the definition of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). A total of 130 patients (51.0 ± 14 years, 34.6% female) were enrolled. Symptoms were common, participants reported a median number of 9 (IQR 5-14) symptoms. Fatigue was the most common symptom (61/130; 46.9%). Patients with fatigue were older 53.9 ± 13.5 years compared with 48.5 ± 13.3 years in those without fatigue (p = 0.02) and had a longer length of hospital stay, 17 ± 14 days vs. 13 ± 10 days (p = 0.04). There was no difference in other comorbidities between patients with fatigue and those without it, and no association between COVID-19 severity and fatigue.

After multivariate adjustment of all baseline clinical features, only age 40 to 50 years old was positively associated with fatigue, OR 2.5 (95% CI 1.05-6.05) p = 0.03. In our survey, only 17 (13%) patients met the Institute of Medicine’s criteria for “systemic exertion intolerance disease,” the new name of ME/CFS. In conclusion, in some patients, the features of post-acute COVID-19 syndrome overlap with the clinical features of ME/CFS.

Source: González-Hermosillo JA, Martínez-López JP, Carrillo-Lampón SA, Ruiz-Ojeda D, Herrera-Ramírez S, Amezcua-Guerra LM, Martínez-Alvarado MDR. Post-Acute COVID-19 Symptoms, a Potential Link with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A 6-Month Survey in a Mexican Cohort. Brain Sci. 2021 Jun 8;11(6):760. doi: 10.3390/brainsci11060760. PMID: 34201087. https://pubmed.ncbi.nlm.nih.gov/34201087/

Insights from myalgic encephalomyelitis/chronic fatigue syndrome may help unravel the pathogenesis of postacute COVID-19 syndrome

Abstract:

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause chronic and acute disease. Postacute sequelae of SARS-CoV-2 infection (PASC) include injury to the lungs, heart, kidneys, and brain that may produce a variety of symptoms. PASC also includes a post-coronavirus disease 2019 (COVID-19) syndrome (‘long COVID’) with features that can follow other acute infectious diseases and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

Here we summarize what is known about the pathogenesis of ME/CFS and of ‘acute’ COVID-19, and we speculate that the pathogenesis of post-COVID-19 syndrome in some people may be similar to that of ME/CFS. We propose molecular mechanisms that might explain the fatigue and related symptoms in both illnesses, and we suggest a research agenda for both ME/CFS and post-COVID-19 syndrome.

Source: Komaroff AL, Lipkin WI. Insights from myalgic encephalomyelitis/chronic fatigue syndrome may help unravel the pathogenesis of postacute COVID-19 syndrome. Trends Mol Med. 2021 Jun 7:S1471-4914(21)00134-9. doi: 10.1016/j.molmed.2021.06.002. Epub ahead of print. PMID: 34175230. https://pubmed.ncbi.nlm.nih.gov/34175230/

Physical and Mental Fatigue in Subjects Recovered from COVID-19 Infection: A Case–Control Study

Abstract:

Purpose: Much effort has been directed toward studying COVID-19 symptoms; however, the post–COVID-19 phase remains mysterious. The aim of this work was to conduct a clinical and neurophysiological evaluation of physical and mental fatigue in COVID-19 long-haulers and to study whether markers of COVID-19 severity are able to predict the likelihood of developing postinfectious fatigue syndrome (PIFS) in such patients.

Patients and Methods: This case–control study was conducted on 46 COVID-19 long-haulers who met the criteria for PIFS and 46 recovered COVID-19 subjects without any residuals. Clinical assessment of fatigue was done using a fatigue questionnaire. Repetitive nerve stimulation and single-fiber electromyography were done after excluding neuropathy and myopathy.

Results: The median value for physical fatigue was 4 (IQR 2– 7), while that for mental fatigue was 2 (IQR 0– 3). Each day’s increase in the period of COVID-19 illness increased the odds of PIFS in COVID-19 long-haulers 1.104-fold, and each unit increase in ferritin increased the odds of PIFS 1.006-fold. A significant decrement in at least one muscle was observed in 50% of patients. Patients with PIFS had significantly higher mean consecutive difference (MCD) in the extensor digitorum communis than the control group. There were statistically significant positive correlations between MCD values and physical, mental, and total fatigue scores.

Conclusion: Higher ferritin levels and prolonged COVID-19 infection were independent predictors of PIFS in COVID-19 long-haulers. There was electrophysiological evidence of abnormalities in the peripheral portion of the motor unit in COVID-19 long-haulers with PIFS.

Source: Elanwar R, Hussein M, Magdy R, Eid RA, Yassien A, Abdelsattar AS, Alsharaway LA, Fathy W, Hassan A, Kamal YS. Physical and Mental Fatigue in Subjects Recovered from COVID-19 Infection: A Case–Control Study. Neuropsychiatr Dis Treat. 2021;17:2063-2071 https://doi.org/10.2147/NDT.S317027 https://www.dovepress.com/physical-and-mental-fatigue-in-subjects-recovered-from-covid-19-infect-peer-reviewed-fulltext-article-NDT (Full text)

Chronic post-COVID-19 syndrome and chronic fatigue syndrome: Is there a role for extracorporeal apheresis?

Abstract:

As millions of patients have been infected by SARS-CoV-2 virus a vast number of individuals complain about continuing breathlessness and fatigue even months after the onset of the disease. This overwhelming phenomenon has not been well defined and has been called “post-COVID syndrome” or “long-COVID” [1]. There are striking similarities to myalgic encephalomyelitis also called chronic fatigue syndrome linked to a viral and autoimmune pathogenesis. In both disorders neurotransmitter receptor antibodies against ß-adrenergic and muscarinic receptors may play a key role. We found similar elevation of these autoantibodies in both patient groups.

Extracorporeal apheresis using a special filter seems to be effective in reducing these antibodies in a significant way clearly improving the debilitating symptoms of patients with chronic fatigue syndrome. Therefore, such a form of neuropheresis may provide a promising therapeutic option for patients with post-COVID-19 syndrome. This method will also be effective when other hitherto unknown antibodies and inflammatory mediators are involved.

Source: Bornstein SR, Voit-Bak K, Donate T, Rodionov RN, Gainetdinov RR, Tselmin S, Kanczkowski W, Müller GM, Achleitner M, Wang J, Licinio J, Bauer M, Young AH, Thuret S, Bechmann N, Straube R. Chronic post-COVID-19 syndrome and chronic fatigue syndrome: Is there a role for extracorporeal apheresis? Mol Psychiatry. 2021 Jun 17. doi: 10.1038/s41380-021-01148-4. Epub ahead of print. PMID: 34140635. https://pubmed.ncbi.nlm.nih.gov/34140635/

Chronic fatigue and post-exertional malaise in people living with long COVID

Abstract:

Purpose People living with long COVID describe a high symptom burden, and a more detailed assessment of chronic fatigue and post-exertional malaise (PEM) may inform the development of rehabilitation recommendations. The aims of this study were to use validated questionnaires to measure the severity of fatigue and compare this with normative data and thresholds for clinical relevance in other diseases; measure and describe the impact of PEM; and describe symptoms of dysfunctional breathing, self-reported physical activity/sitting time, and health-related quality of life.

Methods This was an observational study involving an online survey for adults living with long COVID (data collection from February-April, 2021) following a confirmed or suspected SARS-CoV-2 infection. Questionnaires included the Functional Assessment of Chronic Illness Therapy-Fatigue Scale (FACIT-F) and DePaul Symptom Questionnaire-Post-Exertional Malaise.

Results After data cleaning, n=213 participants were included in the analysis. Participants primarily identified as women (85.5%), aged 40-59 (78.4%), who had been experiencing long COVID symptoms for ≥6 months (72.3%). The total FACIT-F score was 18±10 (where the score can range from 0-52, and a lower score indicates more severe fatigue), and 71.4% were experiencing chronic fatigue. Post-exertional symptom exacerbation affected most participants, and 58.7% met the scoring thresholds used in people living with myalgic encephalomyelitis/chronic fatigue syndrome. PEM occurred alongside a reduced capacity to work, be physically active, and function both physically and socially.

Conclusion Long COVID is characterized by chronic fatigue that is clinically relevant and is at least as severe as fatigue in several other clinical conditions, including cancer. PEM appears to be a common and significant challenge for the majority of this patient group. Patients, researchers, and allied health professionals are seeking information on safe rehabilitation for people living with long COVID, particularly regarding exercise. Fatigue and post-exertional symptom exacerbation must be monitored and reported in studies involving interventions for people with long COVID.

Source: Rosie TwomeyJessica DeMarsKelli FranklinS. Nicole Culos-ReedJason WeatheraldJames G. Wrightson. Chronic fatigue and post-exertional malaise in people living with long COVID.

Insights from Myalgic Encephalomyelitis/Chronic Fatigue Syndrome May Help Unravel the Pathogenesis of Post-Acute COVID-19 Syndrome

Abstract:

SARS-CoV-2 can cause chronic and acute disease. Post-Acute Sequelae of SARS-CoV-2 infection (PASC) include injury to the lungs, heart, kidneys and brain, that may produce a variety of symptoms. PASC also includes a post-COVID-19 syndrome (“long COVID”) with features that can follow other acute infectious diseases as well as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Here we summarize what is known about the pathogenesis of ME/CFS and of acute COVID-19, and speculate that the pathogenesis of post-COVID-19 syndrome in some people may be similar to that of ME/CFS. We propose molecular mechanisms that might explain the fatigue and related symptoms in both illnesses, and suggest a research agenda for both ME/CFS and post-COVID-19 syndrome.

Source: A.L. Komaroff and W.I. Lipkin, Insights from Myalgic Encephalomyelitis/Chronic Fatigue Syndrome May Help Unravel the Pathogenesis of Post-Acute COVID-19 Syndrome, Trends in Molecular Medicine (2021), https://doi.org/ 10.1016/j.molmed.2021.06.002  https://www.cell.com/trends/molecular-medicine/fulltext/S1471-4914(21)00134-9 (Full text)

Post-COVID-19 syndrome: epidemiology, diagnostic criteria and pathogenic mechanisms involved

Abstract in English, Spanish:

Introduction: Many patients with mild or severe COVID-19 do not make a full recovery and have a wide range of chronic symptoms for weeks or months after infection, often of a neurological, cognitive or psychiatric nature. The epidemiological evidence, diagnostic criteria and pathogenesis of post-COVID-19 syndrome are reviewed.

Development: Post-COVID-19 syndrome is defined by persistent clinical signs and symptoms that appear while or after suffering COVID-19, persist for more than 12 weeks and cannot be explained by an alternative diagnosis. The symptoms can fluctuate or cause relapses. It is a heterogeneous condition that includes post-viral chronic fatigue syndrome, sequelae in multiple organs and the effects of severe hospitalisation/post-intensive care syndrome. It has been reported in patients with mild or severe COVID-19 and irrespective of the severity of the symptoms in the acute phase. Between 10% and 65% of survivors who had mild/moderate COVID-19 present symptoms of post-COVID-19 syndrome for 12 weeks or more. At six months, subjects report an average of 14 persistent symptoms. The most common symptoms are fatigue, dyspnoea, anxiety, depression, and impaired attention, concentration, memory and sleep. The underlying biological mechanisms are unknown, although an abnormal or excessive autoimmune and inflammatory response may play an important role.

Conclusions: Clinical manifestations are diverse, fluctuating and variable, although fatigue and neurocognitive complaints predominate. There is no defined consensus on post-COVID-19 syndrome and its diagnostic criteria have not been subjected to adequate psychometric evaluation.

Source: Carod-Artal FJ. Síndrome post-COVID-19: epidemiología, criterios diagnósticos y mecanismos patogénicos implicados [Post-COVID-19 syndrome: epidemiology, diagnostic criteria and pathogenic mechanisms involved]. Rev Neurol. 2021 Jun 1;72(11):384-396. Spanish. doi: 10.33588/rn.7211.2021230. PMID: 34042167. https://pubmed.ncbi.nlm.nih.gov/34042167/