Long Covid: clues about causes

Abstract:(Full text

Many patients report persistent symptoms after resolution of acute COVID-19, regardless of SARS-CoV-2 variant and even if the initial illness is mild [1, 2]. A multitude of symptoms have been described under the umbrella term ‘Long COVID’, otherwise known as ‘post-COVID syndrome’ or ‘post-acute sequelae of SARS-CoV-2 (PASC)’; for simplicity we will use the term Long COVID.

Symptoms are diverse but include breathlessness, fatigue and brain fog, reported to affect up to 69% of cases [3]. Long COVID can be debilitating, 45.2% of patients requiring a reduced work schedule [4]. The WHO estimates that 17 million people in Europe have experienced Long COVID during the first two years of the pandemic [5]. SARS-CoV-2 variants continue to circulate and the risk of post-acute complications remains; a recent study of 56 003 UK patients found that even after Omicron infection, 4.5% suffered persistent symptoms [6].

It is therefore likely that Long COVID will provide a substantial medical and economic burden for the foreseeable future. There is an urgent need to understand mechanisms of disease and develop effective treatments based on this understanding.

Source: Liew F, Efstathiou C, Openshaw PJ. Long Covid: clues about causes. Eur Respir J. 2023 Mar 23:2300409. doi: 10.1183/13993003.00409-2023. Epub ahead of print. PMID: 36958743; PMCID: PMC10040855. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10040855/ (Full text)

What is really ‘Long COVID’?

Abstract:

The previous acute respiratory diseases caused by viruses originating from China or the middle east (e.g., SARS, MERS) remained fast developing short diseases without major sequalae or any long-lasting complications. The new COVID-19, on the other hand, not only that it rapidly spread over the world, but some patients never fully recovered or even if they did, a few weeks later started to complain not only of shortness of breath, if any, but general weakness, muscle pains and ‘brain fog’, i.e., fuzzy memories. Thus, these signs and symptoms were eventually labelled ‘long COVID’, for which the most widely used definition is ‘new signs and symptoms occurring 4-8 weeks after recovering from acute stage of COVID-19’.

The other most frequent manifestations associated with long COVID include headache, loss of memory, smell and of hair, nausea, and vomiting. Thus, long COVID is not a simple disease, but complex disorder of several organ systems malfunctioning; hence, it is probably more appropriate to call this a syndrome.

The pathogenesis of long COVID syndrome is poorly understood, but initial and persistent vascular endothelial injury that often triggers the formation of microthrombi that if dislodged as emboli, damage several organs, especially in the brain, heart and kidney, by creating microinfarcts.

The other major contributory mechanistic factor is the persistent cytokine storm that may last longer in long COVID patients than in others, probably triggered by aggregates of SARS-Co-2 discovered recently in the adrenal cortex, kidney and brain.

The prevalence of long COVID is relatively high, e.g., initially varied 3-30%, and recent data indicate that 2.5% of UK population suffers from this syndrome, while in the US 14.7% of acute COVID-19 patients continued to have symptoms longer than 2 months. Thus, the long COVID syndrome deserves to be further investigated, both from clinical and basic research perspectives.

Source: Szabo S, Zayachkivska O, Hussain A, Muller V. What is really ‘Long COVID’? Inflammopharmacology. 2023 Mar 25:1–7. doi: 10.1007/s10787-023-01194-0. Epub ahead of print. PMID: 36964860; PMCID: PMC10039447. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10039447/ (Full text)

Neurologic manifestations of long COVID differ based on acute COVID-19 severity

Abstract:

Objective: To characterize neurologic manifestations in post-hospitalization Neuro-PASC (PNP) and non-hospitalized Neuro-PASC (NNP) patients.

Methods: Prospective study of the first 100 consecutive PNP and 500 NNP patients evaluated at a Neuro-COVID-19 clinic between 5/2020 and 8/2021.

Results: PNP were older than NNP patients (mean 53.9 vs 44.9 y; p < 0.0001) with a higher prevalence of pre-existing comorbidities. An average 6.8 months from onset, the main neurologic symptoms were “brain fog” (81.2%), headache (70.3%), and dizziness (49.5%) with only anosmia, dysgeusia and myalgias being more frequent in the NNP compared to the PNP group (59 vs 39%, 57.6 vs 39% and 50.4 vs 33%, all p < 0.003). Moreover, 85.8% of patients experienced fatigue. PNP more frequently had an abnormal neurologic exam than NNP patients (62.2 vs 37%, p < 0.0001). Both groups had impaired quality of life in cognitive, fatigue, sleep, anxiety, and depression domains. PNP patients performed worse on processing speed, attention, and working memory tasks than NNP patients (T-score 41.5 vs 55, 42.5 vs 47 and 45.5 vs 49, all p < 0.001) and a US normative population. NNP patients had lower results in attention task only. Subjective impression of cognitive ability correlated with cognitive test results in NNP but not in PNP patients.

Interpretation: PNP and NNP patients both experience persistent neurologic symptoms affecting their quality of life. However, they harbor significant differences in demographics, comorbidities, neurologic symptoms and findings, as well as pattern of cognitive dysfunction. Such differences suggest distinct etiologies of Neuro-PASC in these populations warranting targeted interventions.

Source: Perez Giraldo GS, Ali ST, Kang AK, Patel TR, Budhiraja S, Gaelen JI, Lank GK, Clark JR, Mukherjee S, Singer T, Venkatesh A, Orban ZS, Lim PH, Jimenez M, Miller J, Taylor C, Szymanski AL, Scarpelli J, Graham EL, Balabanov RD, Barcelo BE, Cahan JG, Ruckman K, Shepard AG, Slutzky MW, LaFaver K, Kumthekar PU, Shetty NK, Carroll KS, Ho SU, Lukas RV, Batra A, Liotta EM, Koralnik IJ. Neurologic manifestations of long COVID differ based on acute COVID-19 severity. Ann Neurol. 2023 Mar 26. doi: 10.1002/ana.26649. Epub ahead of print. PMID: 36966460. https://onlinelibrary.wiley.com/doi/abs/10.1002/ana.26649 (Full text available as PDF file)

 

Pathogenic mechanisms of post-acute sequelae of SARS-CoV-2 infection (PASC)

Abstract:

COVID-19, with persistent and new onset of symptoms such as fatigue, post-exertional malaise, and cognitive dysfunction that last for months and impact everyday functioning, is referred to as Long COVID under the general category of post-acute sequelae of SARS-CoV-2 infection (PASC). PASC is highly heterogenous and may be associated with multisystem tissue damage/dysfunction including acute encephalitis, cardiopulmonary syndromes, fibrosis, hepatobiliary damages, gastrointestinal dysregulation, myocardial infarction, neuromuscular syndromes, neuropsychiatric disorders, pulmonary damage, renal failure, stroke, and vascular endothelial dysregulation. A better understanding of the pathophysiologic mechanisms underlying PASC is essential to guide prevention and treatment.

This review addresses potential mechanisms and hypotheses that connect SARS-CoV-2 infection to long-term health consequences. Comparisons between PASC and other virus-initiated chronic syndromes such as myalgic encephalomyelitis/chronic fatigue syndrome and postural orthostatic tachycardia syndrome will be addressed. Aligning symptoms with other chronic syndromes and identifying potentially regulated common underlining pathways may be necessary for understanding the true nature of PASC.

The discussed contributors to PASC symptoms include sequelae from acute SARS-CoV-2 injury to one or more organs, persistent reservoirs of the replicating virus or its remnants in several tissues, re-activation of latent pathogens such as Epstein-Barr and herpes viruses in COVID-19 immune-dysregulated tissue environment, SARS-CoV-2 interactions with host microbiome/virome communities, clotting/coagulation dysregulation, dysfunctional brainstem/vagus nerve signaling, dysautonomia or autonomic dysfunction, 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 specific patients.

Source: Sherif ZA, Gomez CR, Connors TJ, Henrich TJ, Reeves WB; RECOVER Mechanistic Pathway Task Force. Pathogenic mechanisms of post-acute sequelae of SARS-CoV-2 infection (PASC). Elife. 2023 Mar 22;12:e86002. doi: 10.7554/eLife.86002. PMID: 36947108; PMCID: PMC10032659. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10032659/ (Full text)

An Orthomolecular Protocol for Long COVID

Abstract:

A significant number of COVID-19 patients suffer from SARS-CoV-2 post-acute chronic sequelae, also known as post-COVID syndrome or long COVID. These patients report a broad range of persistent and debilitating symptoms such as fatigue, brain fog, pain, breathlessness, and dysrhythmias. These chronic symptoms are believed to be a consequence of excessive production of reactive oxygen species (ROS), inflammation, tissue damage, and mitochondrial dysfunction. Patients at higher risk of long-term sequelae are those who experienced severe COVID-19 infection, are immunocompromised and likely have depleted reserves of biological factors and micronutrients necessary for prompt recovery.

Based on biochemical principles and studies in conditions that share common traits with long COVID patients such as chronic fatigue syndrome and fibromyalgia, symptom relief and sustained recovery can be expected by administering an orthomolecular protocol consisting of a combination of precursors, cofactors, and biological response modifiers.

Source: Gonzalez MJ et al. (2023) An Orthomolecular Protocol for Long-COVID. J Orthomol Med. 38(1) https://www.researchgate.net/publication/369328211_An_Orthomolecular_Protocol_for_Long_COVID (Full text)

Immunometabolic rewiring in long COVID patients with chronic headache

Abstract:

Almost 20% of patients with COVID-19 experience long-term effects, known as post-COVID condition or long COVID. Among many lingering neurologic symptoms, chronic headache is the most common. Despite this health concern, the etiology of long COVID headache is still not well characterized. Here, we present a longitudinal multi-omics analysis of blood leukocyte transcriptomics, plasma proteomics and metabolomics of long COVID patients with chronic headache. L

ong COVID patients experienced a state of hyper-inflammation prior to chronic headache onset and maintained persistent inflammatory activation throughout the progression of chronic headache. Metabolomic analysis also revealed augmented arginine and lipid metabolisms, skewing towards a nitric oxide-based pro-inflammation. Furthermore, metabolisms of neurotransmitters including serotonin, dopamine, glutamate, and GABA were markedly dysregulated during the progression of long COVID headache.

Overall, these findings illustrate the immuno-metabolomics landscape of long COVID patients with chronic headache, which may provide insights to potential therapeutic interventions.

Source: Foo SS, Chen W, Jung KL, Azamor T, Choi UY, Zhang P, Comhair SA, Erzurum SC, Jehi L, Jung JU. Immunometabolic rewiring in long COVID patients with chronic headache. bioRxiv [Preprint]. 2023 Mar 6:2023.03.06.531302. doi: 10.1101/2023.03.06.531302. PMID: 36945569; PMCID: PMC10028820. https://www.biorxiv.org/content/10.1101/2023.03.06.531302v1.full (Full text)

Post-COVID-19 condition at 6 months and COVID-19 vaccination in non-hospitalised children and young people

Abstract:

Objectives: To describe the physical and mental health of children and young people (CYP) 6 months after infection with SARS-CoV-2 and explore whether this varies by COVID-19 vaccination.

Design: A non-hospitalised, national cohort of people aged 11-17 years old with PCR-confirmed SARS-CoV-2 infection and PCR negatives matched at study invitation, by age, sex, region and date of testing who completed questionnaires 6 months after PCR testing. The questionnaire included 21 symptoms and standardised scales (eg, EQ-5D-Y and Chalder Fatigue Scale).

Results: 6407 test-positive and 6542 test-negative CYP completed the 6-month questionnaire: 60.9% of test-positive vs 43.2% of test-negative CYP reported at least one symptom 6 months post-test; 27.6% of test-positive vs 15.9% of test-negative CYP reported 3+ symptoms. Common symptoms at 6 months were tiredness and shortness of breath among both test-positive and test-negative CYP; however, the prevalence of both was higher in test-positive (38.4% and 22.8%, respectively) compared with test-negative CYP (26.7% and 10.9%, respectively). 24.5% test-positive vs 17.8% test-negative CYP met the Delphi research definition of long COVID. Mental health, well-being, fatigue and health-related quality of life scores were similar among test-positive and test-negative CYP 6 months post-test. Similarly, symptomatology was similar among COVID-19-vaccinated and COVID-19-unvaccinated test-positive and test-negative CYP.

Conclusions: Six-months post-PCR testing, CYP who tested positive for SARS-CoV-2 had similar symptoms to those who tested negative, but test-positive CYP had higher symptom prevalence. Mental health, well-being, fatigue and health-related quality of life were similar among test-positive and test-negative CYP, and symptoms at 6 months were similar in COVID-19 vaccinated and unvaccinated.

Source: Pinto Pereira SM, Nugawela MD, Rojas NK, Shafran R, McOwat K, Simmons R, Ford T, Heyman I, Ladhani SN, Cheung EY, Fox-Smith L, Dalrymple E, Stephenson T. Post-COVID-19 condition at 6 months and COVID-19 vaccination in non-hospitalised children and young people. Arch Dis Child. 2023 Apr;108(4):289-295. doi: 10.1136/archdischild-2022-324656. Epub 2023 Jan 4. PMID: 36599625. https://adc.bmj.com/content/108/4/289.long (Full text)

Pooled Prevalence of Long COVID-19 Symptoms at 12 Months and Above Follow-Up Period: A Systematic Review and Meta-Analysis

Abstract:

Current data suggests that coronavirus disease 2019 (COVID-19) survivors experience long-lasting problems. It is not yet understood how long these symptoms last. The goal of this study was to compile all the data that was currently available to evaluate COVID-19’s long-term effects at 12 months and above.

We looked for studies published by December 15, 2022, in PubMed and Embase that discussed follow-up findings for COVID-19 survivors who had been alive for at least a year. A random-effect model was carried out to determine the combined prevalence of different long-COVID symptoms. The Joanna Briggs Institute tool was used to assess the risk of bias for the included studies, and the I2 statistics were used to evaluate the heterogeneity. After reviewing 3,209 studies, 46 were deemed admissible, with an aggregate COVID-19 population of 17976.

At 12 months and above, 57% of patients reported a minimum of one symptom, and the five most prevalent symptoms were: dyspnea on exertion (34%, 95% CI 0.2; 0.94); difficulty in concentration (32%, 95% CI 0.16; 0.52); fatigue (31%, 95% CI 0.22; 0.40); frailty (31%, 95% CI 0.06; 0.78); and arthromyalgia (28%, 95% CI 0.09; 0.6). The findings of the present study showed that at 12 months and beyond, a sizable fraction of COVID-19 survivors still have lasting symptoms that impair several body systems. Long-COVID patients require an urgent understanding of pathophysiological processes and the development of tailored treatments.

Source: Mudgal S K, Gaur R, Rulaniya S, et al. (March 18, 2023) Pooled Prevalence of Long COVID-19 Symptoms at 12 Months and Above Follow-Up Period: A Systematic Review and Meta-Analysis. Cureus 15(3): e36325. doi:10.7759/cureus.36325 https://www.cureus.com/articles/143288-pooled-prevalence-of-long-covid-19-symptoms-at-12-months-and-above-follow-up-period-a-systematic-review-and-meta-analysis#!/ (Full text)

Not myopathic, but autonomic changes in patients with long-COVID syndrome: a case series

Abstract:

Introduction: Neurological sequelae following SARS-CoV-2 infection still represent a serious concern both for neurologists and neuroscientists. In our paper, we investigated pain, myalgia, and fatigue as symptoms in long-COVID patients with an electrophysiological approach, comprising the evaluation of sympathetic skin responses (SSRs) and quantitative electromyography (qEMG).

Materials and methods: Twelve patients were enrolled (mean age, 47.7 ± 11.6 years), referred to our attention because of myalgia, pain, or muscle cramps, which persisted about 6 months after the diagnosis of SARS-CoV-2 infection. They underwent conventional electroneurography (ENG), needle electromyography (EMG), and SSRs; moreover, qEMG was performed by sampling at least 20 motor unit potentials (20-30 MUPs) during weak voluntary contraction in deltoid and tibialis anterior muscles. The mean duration, amplitude, and percentage of polyphasic potentials were assessed and compared with healthy and age-matched volunteers.

Results: ENG did not disclose significant changes compared to healthy subjects; needle EMG did not reveal denervation activity. In addition, qEMG showed MUPs similar to those recorded in healthy volunteers in terms of polyphasia (deltoid: p = 0.24; TA: p = 0.35), MUP area (deltoid: p = 0.45; TA: p = 0.44), mean duration (deltoid: p = 0.06; TA: p = 0.45), and amplitude (deltoid: p = 0.27; TA: p = 0.63). SSRs were not recordable from lower limbs in seven patients (58%) and from the upper ones in three of them (25%).

Conclusion: Our data suggest an involvement of the autonomic system, with a focus on cholinergic efferent sympathetic activity, without any evidence of myopathic changes.

Source: Bocci T, Bertini A, Campiglio L, Botta S, Libelli G, Guidetti M, Priori A. Not myopathic, but autonomic changes in patients with long-COVID syndrome: a case series. Neurol Sci. 2023 Apr;44(4):1147-1153. doi: 10.1007/s10072-023-06637-8. Epub 2023 Feb 3. PMID: 36735149; PMCID: PMC9896447. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9896447/ (Full study)

Understanding pediatric long COVID using a tree-based scan statistic approach: an EHR-based cohort study from the RECOVER Program

Abstract:

Objectives: Post-acute sequalae of SARS-CoV-2 infection (PASC) is not well defined in pediatrics given its heterogeneity of presentation and severity in this population. The aim of this study is to use novel methods that rely on data mining approaches rather than clinical experience to detect conditions and symptoms associated with pediatric PASC.

Materials and methods: We used a propensity-matched cohort design comparing children identified using the new PASC ICD10CM diagnosis code (U09.9) (N = 1309) to children with (N = 6545) and without (N = 6545) SARS-CoV-2 infection. We used a tree-based scan statistic to identify potential condition clusters co-occurring more frequently in cases than controls.

Results: We found significant enrichment among children with PASC in cardiac, respiratory, neurologic, psychological, endocrine, gastrointestinal, and musculoskeletal systems, the most significant related to circulatory and respiratory such as dyspnea, difficulty breathing, and fatigue and malaise.

Discussion: Our study addresses methodological limitations of prior studies that rely on prespecified clusters of potential PASC-associated diagnoses driven by clinician experience. Future studies are needed to identify patterns of diagnoses and their associations to derive clinical phenotypes.

Conclusion: We identified multiple conditions and body systems associated with pediatric PASC. Because we rely on a data-driven approach, several new or under-reported conditions and symptoms were detected that warrant further investigation.

Source: Lorman V, Rao S, Jhaveri R, Case A, Mejias A, Pajor NM, Patel P, Thacker D, Bose-Brill S, Block J, Hanley PC, Prahalad P, Chen Y, Forrest CB, Bailey LC, Lee GM, Razzaghi H. Understanding pediatric long COVID using a tree-based scan statistic approach: an EHR-based cohort study from the RECOVER Program. JAMIA Open. 2023 Mar 14;6(1):ooad016. doi: 10.1093/jamiaopen/ooad016. PMID: 36926600; PMCID: PMC10013630. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10013630/ (Full text)