The immunology of long COVID

Executive deficits after SARS-CoV-2 infection: A cross-sectional population study

Importance

Despite the major implications of executive deficits in day-to-day functioning, few studies have investigated this in post-acute sequelae of SARS-CoV-2 infection using standardized measures that differentiate between aspects of executive function.

Objective

Examine whether SARS-CoV-2 infection is associated with deficits in executive functions and if so, investigate the duration of this association.

Design Setting and Participants

The present research has a cross-sectional design and uses data from the Norwegian Covid-19 Cohort study. The current cohort (n = 8102) completed the Behavior Rating Inventory of Executive Function- Adult Version (BRIEF-A) electronically between April 2021 and September 2021. During the assessment, 4183 of the included participants had a prior positive polymerase chain reaction test (PCR) for SARS-CoV-2 and 3919 were untested or had a confirmed negative PCR test.

Exposure

Laboratory-confirmed SARS-CoV-2 infection.

Main outcomes and measures

Executive functions were measured using the BRIEF-A, a self-report questionnaire comprising 75 items within nine theoretically and empirically distinct clinical scales. All participants self-reported on demographical variables and comorbidity. Information on sex and age was derived from the personal identification number, and vaccination status was obtained from the Norwegian Immunization Registry (SYSVAK).

Results

Participants with a positive SARS-CoV-2 status reported executive deficits in everyday life above the clinical threshold (T-score ≥65) more often than non-infected controls (383 vs. 225). Specifically, the SARS-CoV-2 positive status group indicated significantly more deficits related to metacognition, with the greatest difference demonstrated for working memory. This difference remained when adjusting for various demographic factors and comorbidities, with significantly greater odds of reporting above the clinical threshold following SARS-CoV-2 infection, as observed on the global executive composite score 6-12 months after infection (OR 1.97; 95% CI 1.51 to 2.55).

Conclusions

Our study confirms more perceived executive deficits following SARS-CoV-2 infection compared to non-infected controls, with metacognitive aspects being the most affected. These findings shed light on the potential functional difficulties that individuals may encounter during the post-acute phase of SARS-CoV-2 infection and may guide further development of targeted interventions addressing metacognitive domains of executive functioning.

Long COVID and gut candidiasis: What is the existing relationship?

Since the beginning of the coronavirus disease (COVID) 2019 pandemic, thousands of articles on the topic have been published, and although there is a growing trend of research on another associated condition, long coronavirus disease, important points still remain to be clarified in this respect. Robust evidence has suggested a relevant link between new clinical discoveries and molecular mechanisms that could be associated with the manifestations of different signs and symptoms involving cases of long COVID. However, one of the existing gaps that requires further investigation concerns a possible relationship between gut candidiasis and long COVID. While recent studies also suggest an interplay between the occurrence of these two conditions, it is not yet fully clear how this may happen, as well as the specifics regarding the possible pathophysiological mechanisms involved. In this connection and with the advent of a potential strengthening of the body of evidence supporting the hypothesis of a link between gut candidiasis and long COVID, a better understanding of the clinical presentation, pathophysiology and clinical management of such a relationship should be essential and useful for both, additional advances towards more targeted research and appropriate case management. Knowing more about the signs, symptoms, and complications associated with cases of long COVID is essential in order to more effectively mitigate the related burden and provide a higher quality of care and life for the affected population. In light of this and the need for better outcomes, here we review and discuss the content on different aspects of long COVID, including its pathophysiology and the existing evidence of a potential relationship between such a condition and gut candidiasis, as well as suggest propositions for future related research.

A practical framework for Long COVID treatment in primary care

Long COVID is a complex, multisystem illness with a poorly understood pathophysiology, absence of specific diagnostic tests or criteria, or evidence-based treatments. With over 200 identified symptoms and approximately 10% of COVID-19 cases resulting in Long COVID, it is a challenge to provide comprehensive treatment at a scale commensurate with the illness burden. The diverse manifestations of Long COVID, encompassing numerous medical specialties, typically place primary care providers (PCPs) at the forefront of management, navigating an evolving landscape of research and lack of evidence-based guidelines. This paper presents a pragmatic, structured framework for Long COVID management in primary care, integrating current knowledge and best practices. The approach is individualized, addressing Long COVID's broad symptomatology through a four-step framework. The first step focuses on energy management strategies, emphasizing the prevention of post-exertional malaise, a cardinal feature of Long COVID. The second step, intentional rehabilitation, employs carefully titrated multidisciplinary modalities to address physical, cognitive, and emotional domains. The third step utilizes symptomatic management through both pharmacological and non-pharmacological interventions, targeting debilitating symptoms like fatigue, insomnia, and chronic pain. The fourth step outlines an approach to trialing experimental, targeted therapies that may impact Long COVID's underlying pathophysiology. These treatments, while experimental and lacking quality evidence in Long COVID, may be available off-label on an individual basis following a thorough risk-benefit discussion. This stepwise framework can equip PCPs to effectively address the most common and disabling symptoms of Long COVID, individualize care, and remain attuned to the evolving scientific understanding of the condition.

Short-term intermittent hypoxia exposure for dyspnea and fatigue in post-acute sequelae of COVID-19: A randomized controlled study

BACKGROUND

Post-acute sequelae of COVID-19 (PASC) is incurring a huge health and economic burden worldwide. There is currently no effective treatment or recommended drug for PASC.

METHODS

This prospective randomized controlled study was conducted in a hospital in China. The effect of intermittent hypoxia exposure (IHE; 5-min hypoxia alternating with 5-min normal air, repeated five times) on dyspnea and fatigue was investigated in patients meeting the NICE definition of PASC. Patients were computationally randomized to receive normoxia exposure (NE) and routine therapy or IHE and routine therapy. Six-minute walk distance (6MWD) and spirometry were tested before and after the interventions; the Borg Dyspnea Scale (Borg) and the modified Medical Research Council Dyspnea Scale (mMRC) were used to assess dyspnea; and the Fatigue Assessment Scale (FAS) and the Chalder Fatigue Scale-11 (CFQ-11) were used to assess fatigue. The study was registered in the Chinese Clinical Trial Registry (ChiCTR2300070565).

FINDINGS

Ninety-five participants (33 males and 62 females) were recruited between March 1, 2023 and December 30, 2023. Forty-seven patients in the IHE group received 10.0 (9.0, 15.0) days of IHE, and 48 patients in NE group received 10.0 (8.0, 12.0) days of NE. 6MWD, forced vital capacity (FVC), FVC %pred, forced expiratory volume in 1 s (FEV1), FEV1 %pred, tidal volume (VT), and dyspnea and fatigue scales markedly improved after IHE (p < 0.05), and improvements were greater than in the NE group (all p < 0.05). Furthermore, participants in IHE group had better subjective improvements in dyspnea and fatigue than those in the NE group (p < 0.05). Compared with <10 days of IHE, ≥10 days of IHE had a greater impact on 6MWD, FVC, FEV1, FEV1 %pred, VT, FAS, and CFQ-11. No severe adverse events were reported.

INTERPRETATION

IHE improved spirometry and 6MWD and relieved dyspnea and fatigue in PASC patients. Larger prospective studies are now needed to verify these findings.

Host response to Aplysia Abyssovirus 1 in nervous system and gill

The California sea hare (Aplysia californica) is a model for age associated cognitive decline. Recent researched identified a novel nidovirus, Aplysia Abyssovirus 1, with broad tropism enriched in the Aplysia nervous system. This virus is ubiquitous in wild and maricultured, young and old animals without obvious pathology. Here we re-evaluated gene expression data from several previous studies to investigate differential expression in the nervous system and gill in response to virus and aging as well as the mutational spectrum observed in the viral sequences obtained from these datasets. Viral load and age were highly correlated, indicating persistent infection. Upregulated genes in response to virus were enriched for immune genes and signatures of ER and proteostatic stress, while downregulated genes were enriched for mitochondrial metabolism. Differential expression with respect to age suggested increased iron accumulation and decreased glycolysis, fatty acid metabolism, and proteasome function. Interaction of gene expression trends associated with viral infection and aging suggest that viral infection likely plays a role in aging in the Aplysia nervous system. Mutation analysis of viral RNA identified signatures suggesting ADAR and AID/APOBEC like deaminase act as part of Aplysia anti-viral defense.

Vascular Pathogenesis in Acute and Long COVID: Current Insights and Therapeutic Outlook

Long coronavirus disease 2019 (COVID-19)-a postacute consequence of severe acute respiratory syndrome coronavirus 2 infection-manifests with a broad spectrum of relapsing and remitting or persistent symptoms as well as varied levels of organ damage, which may be asymptomatic or present as acute events such as heart attacks or strokes and recurrent infections, hinting at complex underlying pathogenic mechanisms. Central to these symptoms is vascular dysfunction rooted in thrombotic endothelialitis. We review the scientific evidence that widespread endothelial dysfunction (ED) leads to chronic symptomatology. We briefly examine the molecular pathways contributing to endothelial pathology and provide a detailed analysis of how these cellular processes underpin the clinical picture. Noninvasive diagnostic techniques, such as flow-mediated dilation and peripheral arterial tonometry, are evaluated for their utility in identifying ED. We then explore mechanistic, cellular-targeted therapeutic interventions for their potential in treating ED. Overall, we emphasize the critical role of cellular health in managing Long COVID and highlight the need for early intervention to prevent long-term vascular and cellular dysfunction.

Targeting Cytokines: Evaluating the Potential of Mesenchymal Stem Cell Derived Extracellular Vesicles in the Management of COVID-19

The Coronavirus Disease 2019 (COVID-19), caused by virus SARS-CoV-2, is characterized by massive inflammation and immune system imbalance. Despite the implementation of vaccination protocols, the accessibility of treatment remains uneven. Furthermore, the persistent threat of new variants underscores the urgent need for expanded research into therapeutic options for SARS-CoV-2. Mesenchymal stem cells (MSCs) are known for their immunomodulatory potential through the release of molecules into the extracellular space, either as soluble elements or carried by extracellular vesicles (EVs). The aim of this study was to evaluate the anti-inflammatory potential of EVs obtained from human adipose tissue (ASC-EVs) against SARS-CoV-2 infection. ASC-EVs were purified by size-exclusion chromatography, and co-culture assays confirmed that ASC-EVs were internalized by human lung cells and could colocalize with SARS-CoV-2 into early and late endosomes. To determine the functionality of ASC-EVs, lung cells were infected with SARS-CoV-2 in the presence of increasing concentrations of ASC-EVs, and the release of cytokines, chemokines and viruses were measured. While SARS-CoV-2 replication was significantly reduced only at the highest concentrations tested, multiplex analysis highlighted that lower concentrations of ASC-EV sufficed to prevent the production of immune modulators. Importantly, ASC-EVs did not contain detectable inflammatory cytokines, nor did they trigger inflammatory mediators, nor affect cellular viability. In conclusion, this work suggests that ASC-EVs have the potential to attenuate inflammation by decreasing the production of pro-inflammatory cytokines in lung cells following SARS-CoV-2 infection.

Mechanisms of long COVID and the path toward therapeutics

Long COVID, a type of post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (PASC) defined by medically unexplained symptoms following infection with SARS-CoV-2, is a newly recognized infection-associated chronic condition that causes disability in some people. Substantial progress has been made in defining its epidemiology, biology, and pathophysiology. However, there is no cure for the tens of millions of people believed to be experiencing long COVID, and industry engagement in developing therapeutics has been limited. Here, we review the current state of knowledge regarding the biology and pathophysiology of long COVID, focusing on how the proposed mechanisms explain the physiology of the syndrome and how they provide a rationale for the implementation of a broad experimental medicine and clinical trials agenda. Progress toward preventing and curing long COVID and other infection-associated chronic conditions will require deep and sustained investment by funders and industry.

SARS-CoV-2-specific CD8+ T cells from people with long COVID establish and maintain effector phenotype and key TCR signatures over 2 years

Long COVID occurs in a small but important minority of patients following COVID-19, reducing quality of life and contributing to healthcare burden. Although research into underlying mechanisms is evolving, immunity is understudied. SARS-CoV-2-specific T cell responses are of key importance for viral clearance and COVID-19 recovery. However, in long COVID, the establishment and persistence of SARS-CoV-2-specific T cells are far from clear, especially beyond 12 mo postinfection and postvaccination. We defined ex vivo antigen-specific B cell and T cell responses and their T cell receptors (TCR) repertoires across 2 y postinfection in people with long COVID. Using 13 SARS-CoV-2 peptide-HLA tetramers, spanning 11 HLA allotypes, as well as spike and nucleocapsid probes, we tracked SARS-CoV-2-specific CD8+ and CD4+ T cells and B-cells in individuals from their first SARS-CoV-2 infection through primary vaccination over 24 mo. The frequencies of ORF1a- and nucleocapsid-specific T cells and B cells remained stable over 24 mo. Spike-specific CD8+ and CD4+ T cells and B cells were boosted by SARS-CoV-2 vaccination, indicating immunization, in fully recovered and people with long COVID, altered the immunodominance hierarchy of SARS-CoV-2 T cell epitopes. Meanwhile, influenza-specific CD8+ T cells were stable across 24 mo, suggesting no bystander-activation. Compared to total T cell populations, SARS-CoV-2-specific T cells were enriched for central memory phenotype, although the proportion of central memory T cells decreased following acute illness. Importantly, TCR repertoire composition was maintained throughout long COVID, including postvaccination, to 2 y postinfection. Overall, we defined ex vivo SARS-CoV-2-specific B cells and T cells to understand primary and recall responses, providing key insights into antigen-specific responses in people with long COVID.

Deciphering the role of FOXP4 in long COVID: exploring genetic associations, evolutionary conservation, and drug identification through bioinformatics analysis

Long COVID (LC) refers to a condition characterized by a variety of lingering symptoms that persist for more than 4 to 12 weeks following the initial acute SARS-CoV-2 infection. Recent research has suggested that the FOXP4 gene could potentially be a significant factor contributing to LC. Owing to that, this study investigates FOXP4's role in LC by analyzing public datasets to understand its evolution and expression in diverse human populations and searching for drugs to reduce LC symptoms. Population genetic analysis of FOXP4 across human populations unmasks distinct genetic diversity patterns and positive selection signatures, suggesting potential population-specific susceptibilities to conditions like LC. Further, we also observed that FOXP4 experiences high expression during LC. To identify potential inhibitors, drug screening analysis identifies synthetic drugs like Glisoxepide, and natural compounds Kapurimycin A3 produced from Streptomyces sp, and Cucurbitacin B from Begonia nantoensis as promising candidates. Overall, our research contributes to understanding how FOXP4 may serve as a therapeutic target for mitigating the impact of LC.

The Role of ACE2 in Neurological Disorders: From Underlying Mechanisms to the Neurological Impact of COVID-19

Angiotensin-converting enzyme 2 (ACE2) has become a hot topic in neuroscience research in recent years, especially in the context of the global COVID-19 pandemic, where its role in neurological diseases has received widespread attention. ACE2, as a multifunctional metalloprotease, not only plays a critical role in the cardiovascular system but also plays an important role in the protection, development, and inflammation regulation of the nervous system. The COVID-19 pandemic further highlights the importance of ACE2 in the nervous system. SARS-CoV-2 enters host cells by binding to ACE2, which may directly or indirectly affect the nervous system, leading to a range of neurological symptoms. This review aims to explore the function of ACE2 in the nervous system as well as its potential impact and therapeutic potential in various neurological diseases, providing a new perspective for the treatment of neurological disorders.

Immune Jumping in Autoimmune Long-Covid

This Long-Covid disease, mild or severe, is multiorgan or system-wide, spanning from fatigue to clotting abnormalities and autoantibody. The spectrum of different symptoms in Long-Covid diseases makes it difficult to point to a common immunopathogenic etiology. Different immune pathways are presented and critically evaluated. A hypothesis is advanced that indicates autoimmune reactions as cause for Long-Covid disease. The immune network pathway describes a redirection of the nominal anti-SARS-CoV response towards an autoimmune target. Several therapeutic interventions are suggested to suppress the autoimmune pathway.

Postacute Sequelae of COVID (PASC or Long COVID): An Evidenced-Based Approach

While the acute manifestations of infectious diseases are well known, in some individuals, symptoms can either persist or appear after the acute period. Postviral fatigue syndromes are recognized with other viral infections and are described after coronavirus disease 2019 (COVID-19). We have a growing number of individuals with symptoms that persist for weeks, months, and years. Here, we share the evidence regarding the abnormalities associated with postacute sequelae of COVID-19 (PASC) and therapeutics. We describe physiological and biochemical abnormalities seen in individuals reporting PASC. We describe the several evidence-based interventions to offer patients. It is expected that this growing understanding of the mechanisms driving PASC and the benefits seen with certain therapeutics may not only lead to better outcomes for those with PASC but may also have the potential for understanding and treating other postinfectious sequelae.

Ocular manifestations of COVID-19

There is an increasing body of knowledge regarding how COVID-19 may be associated with ocular disease of varying severity and duration. This article discusses the literature on the ocular manifestations associated with COVID-19, including appraisal of the current evidence, suggested mechanisms of action, associated comorbidities and risk factors, timing from initial infection to diagnosis and clinical red flags. The current literature primarily comprises case reports and case series which inevitably lack control groups and evidence to support causality. However, these early data have prompted the development of larger population-based and laboratory studies that are emerging. As new data become available, a better appraisal of the true effects of COVID-19 on the eye will be possible. While the COVID-19 pandemic was officially declared no longer a "global health emergency" by the World Health Organization (WHO) in May 2023, case numbers continue to rise. Reinfection with different variants is predicted to lead to a growing cumulative burden of disease, particularly as more chronic, multi-organ sequelae become apparent with potentially significant ocular implications. COVID-19 ocular manifestations are postulated to be due to three main mechanisms: firstly, there is a dysregulated immune response to the initial infection linked to inflammatory eye disease; secondly, patients with COVID-19 have a greater tendency towards a hypercoagulable state, leading to prothrombotic events; thirdly, patients with severe COVID-19 requiring hospitalisation and are immunosuppressed due to administered corticosteroids or comorbidities such as diabetes mellitus are at an increased risk of secondary infections, including endophthalmitis and rhino-orbital-mucormycosis. Reported ophthalmic associations with COVID-19, therefore, include a range of conditions such as conjunctivitis, scleritis, uveitis, endogenous endophthalmitis, corneal graft rejection, retinal artery and vein occlusion, non-arteritic ischaemic optic neuropathy, glaucoma, neurological and orbital sequelae. With the need to consider telemedicine consultation in view of COVID-19's infectivity, understanding the range of ocular conditions that may present during or following infection is essential to ensure patients are appropriately triaged, with prompt in-person ocular examination for management of potentially sight-threatening and life-threatening diseases.

Human herpesvirus reactivation and its potential role in the pathogenesis of post-acute sequelae of SARS-CoV-2 infection

The emergence of SARS-CoV-2 has precipitated a global pandemic with substantial long-term health implications, including the condition known as post-acute sequelae of SARS-CoV-2 infection (PASC), commonly referred to as Long COVID. PASC is marked by persistent symptoms such as fatigue, neurological issues, and autonomic dysfunction that persist for months beyond the acute phase of COVID-19. This review examines the potential role of herpesvirus reactivation, specifically Epstein-Barr virus (EBV) and cytomegalovirus (CMV), in the pathogenesis of PASC. Elevated antibody titers and specific T cell responses suggest recent herpesvirus reactivation in some PASC patients, although viremia is not consistently detected. SARS-CoV-2 exhibits endothelial trophism, directly affecting the vascular endothelium and contributing to microvascular pathologies. These pathologies are significant in PASC, where microvascular dysfunction may underlie various chronic symptoms. Similarly, herpesviruses like CMV also exhibit endothelial trophism, which may exacerbate endothelial damage when reactivated. Evidence suggests that EBV and CMV reactivation could indirectly contribute to the immune dysregulation, immunosenescence, and autoimmune responses observed in PASC. Additionally, EBV may play a role in the genesis of neurological symptoms through creating mitochondrial dysfunction, though direct confirmation remains elusive. The reviewed evidence suggests that while herpesviruses may not play a direct role in the pathogenesis of PASC, their potential indirect effects, especially in the context of endothelial involvement, warrant further investigation.

Inflammatory pathways in patients with post-acute sequelae of COVID-19: The role of the clinical immunologist

As the SARS-CoV-2 pandemic progressed, some survivors noted prolonged symptoms after acute infection, termed post-acute sequelae of COVID-19 (PASC) or "long COVID." PASC is a significant clinical and public health concern that adversely affects patients' quality of life, income, and health care expenses. Moreover, PASC symptoms are highly heterogeneous, the most common being fatigue and cognitive impairment, and they likely reflect a spectrum of clinical phenotypes. The proposed role of persistent inflammation is one of leading pathophysiological theories. This review article addresses these proposed mechanisms of persistent and aberrant inflammation, their clinical evaluation, and theoretical approaches to management. A review of public databases was used to collect literature for the review. The literature supports a prominent role of persistent and aberrant inflammation as a major contributor to the symptoms of PASC. Proposed mechanisms for persistent inflammation include reactivation of latent viruses, viral persistence, loss of immunoregulatory pathways, autoimmune mechanisms, and/or mast cell dysregulation. Persistent inflammation may result in constitutional symptoms such as fatigue, brain fog, body aches, and/or organ-specific dysfunction, such as gastrointestinal dysregulation and myocardial inflammation. There are no approved or even proven therapies for PASC at this time, but some studies have identified therapeutic options that may either reduce the risk for progression to PASC or decrease symptom burden. Laboratory evaluation and therapeutic options are limited and require further investigation to establish their clinical value. A more refined definition of PASC is needed to address the wide variety of clinical presentations, pathophysiology, and therapeutic options.

Navigating Complexity in Postural Orthostatic Tachycardia Syndrome

Postural Orthostatic Tachycardia Syndrome (POTS) affects up to 1% of the US population, predominantly women, and is characterized by a complex, elusive etiology and heterogeneous phenotypes. This review delves into the intricate physiology and etiology of POTS, decoding the roles of the sinoatrial node, the autonomic nervous system, fluid dynamics, and the interplay between the immune and endocrine systems. It further examines key contributing factors such as dysautonomia, thoracic hypovolemia, autonomic neuropathies, sympathetic denervation, autoimmune responses, and associations with conditions such as small-fiber neuropathy and mast cell activation syndrome. Given the numerous mysteries surrounding POTS, we also cautiously bring attention to sinoatrial node and myocardial function, particularly in how the heart responds to stress despite exhibiting a normal cardiac phenotype at rest. The potential of genomic research in elucidating the underlying mechanisms of POTS is emphasized, suggesting this as a valuable approach that is likely to improve our understanding of the genetic underpinnings of POTS. The review introduces a tentative classification system for the etiological factors in POTS, which seeks to capture the condition's diverse aspects by categorizing various etiological factors and acknowledging co-occurring conditions. This classification, while aiming to enhance understanding and optimize treatment targets, is presented as a preliminary model needing further study and refinement. This review underscores the ongoing need for research to unravel the complexities of POTS and to develop targeted therapies that can improve patient outcomes.

Non-human primate model of long-COVID identifies immune associates of hyperglycemia

Hyperglycemia, and exacerbation of pre-existing deficits in glucose metabolism, are manifestations of the post-acute sequelae of SARS-CoV-2. Our understanding of metabolic decline after acute COVID-19 remains unclear due to the lack of animal models. Here, we report a non-human primate model of metabolic post-acute sequelae of SARS-CoV-2 using SARS-CoV-2 infected African green monkeys. Using this model, we identify a dysregulated blood chemokine signature during acute COVID-19 that correlates with elevated and persistent hyperglycemia four months post-infection. Hyperglycemia also correlates with liver glycogen levels, but there is no evidence of substantial long-term SARS-CoV-2 replication in the liver and pancreas. Finally, we report a favorable glycemic effect of the SARS-CoV-2 mRNA vaccine, administered on day 4 post-infection. Together, these data suggest that the African green monkey model exhibits important similarities to humans and can be utilized to assess therapeutic candidates to combat COVID-related metabolic defects.

Mononuclear Phagocytes, Cellular Immunity, and Nobel Prizes: A Historic Perspective

The mononuclear phagocyte system includes monocytes, macrophages, some dendritic cells, and multinuclear giant cells. These cell populations display marked heterogeneity depending on their differentiation from embryonic and bone marrow hematopoietic progenitors, tissue location, and activation. They contribute to tissue homeostasis by interacting with local and systemic immune and non-immune cells through trophic, clearance, and cytocidal functions. During evolution, they contributed to the innate host defense before effector mechanisms of specific adaptive immunity emerged. Mouse macrophages appear at mid-gestation and are distributed throughout the embryo to facilitate organogenesis and clear cells undergoing programmed cell death. Yolk sac, AGM, and fetal liver-derived tissue-resident macrophages persist throughout postnatal and adult life, supplemented by bone marrow-derived blood monocytes, as required after injury and infection. Nobel awards to Elie Metchnikoff and Paul Ehrlich in 1908 drew attention to cellular phagocytic and humoral immunity, respectively. In 2011, prizes were awarded to Jules Hoffmann and Bruce Beutler for contributions to innate immunity and to Ralph Steinman for the discovery of dendritic cells and their role in antigen presentation to T lymphocytes. We trace milestones in the history of mononuclear phagocyte research from the perspective of Nobel awards bearing directly and indirectly on their role in cellular immunity.

Long COVID: a clinical update

Post-COVID-19 condition (also known as long COVID) is generally defined as symptoms persisting for 3 months or more after acute COVID-19. Long COVID can affect multiple organ systems and lead to severe and protracted impairment of function as a result of organ damage. The burden of this disease, both on the individual and on health systems and national economies, is high. In this interdisciplinary Review, with a coauthor with lived experience of severe long COVID, we sought to bring together multiple streams of literature on the epidemiology, pathophysiology (including the hypothesised mechanisms of organ damage), lived experience and clinical manifestations, and clinical investigation and management of long COVID. Although current approaches to long COVID care are largely symptomatic and supportive, recent advances in clinical phenotyping, deep molecular profiling, and biomarker identification might herald a more mechanism-informed and personally tailored approach to clinical care. We also cover the organisation of services for long COVID, approaches to preventing long COVID, and suggestions for future research.

Comparative SARS-CoV-2 Omicron BA.5 variant and D614G-Wuhan strain infections in ferrets: insights into attenuation and disease progression during subclinical to mild COVID-19

Introduction

As the SARS-CoV-2 virus continues to evolve and new variants emerge, it becomes crucial to understand the comparative pathological and immunological responses elicited by different strains. This study focuses on the original Wuhan strain and the Omicron variant, which have demonstrated significant differences in clinical outcomes and immune responses.

Methods

We employed ferrets as an experimental model to assess the D614G variant (a derivative of the Wuhan strain) and the Omicron BA.5 variant. Each variant was inoculated into separate groups of ferrets to compare disease severity, viral dissemination, and immune responses.

Results

The D614G variant induced more severe disease and greater viral spread than the Omicron variant. Notably, ferrets infected with the D614G variant exhibited a robust neutralizing antibody response, whereas those infected with the Omicron variant failed to produce a detectable neutralizing antibody response. Despite the clearance of the virus from nearly all tissues by 7 days post-infection, an increase in pathological lesions was observed from 14 to 21 days, particularly in those infected with the D614G variant, suggesting a sustained immune response even after viral clearance.

Discussion

These findings underscore the adaptability of SARS-CoV-2 and illuminate how susceptibility and clinical manifestations vary across different strains and species. The results emphasize the necessity of considering both the direct effects of viral infection and the indirect, often prolonged, impacts of the immune response in evaluating the outcomes of SARS-CoV-2 infections.

Higher intraindividual variability of body mass index is associated with elevated risk of COVID-19 related hospitalization and post-COVID conditions

BACKGROUND

Cardiometabolic diseases are risk factors for COVID-19 severity. The extent that cardiometabolic health represents a modifiable factor to mitigate the short- and long-term consequences from SARS-CoV-2 remains unclear. Our objective was to evaluate the associations between intraindividual variability of cardiometabolic health indicators and COVID-19 related hospitalizations and post-COVID conditions (PCC) among a relatively healthy population.

METHODS

This retrospective, multi-site cohort study was a post-hoc analysis among individuals with cardiometabolic health data collected during routine blood donation visits in 24 US states (2009-2018) and who responded to COVID-19 questionnaires (2021-2023). Intraindividual variability of blood pressure (systolic, diastolic), total circulating cholesterol, and body mass index (BMI) were defined as the coefficient of variation (CV) across all available donation timepoints (ranging from 3 to 74); participants were categorized into CV quartiles. Associations were evaluated by multivariable binomial regressions.

RESULTS

Overall, 3344 participants provided 42,090 donations (median 9 [IQR 5, 17]). The median age was 48 years (38, 56) at the first study donation. 1.2% (N = 40) were hospitalized due to COVID-19 and 15.5% (N = 519) had PCC. Higher BMI variability was associated with greater risk of COVID-19 hospitalization (4th quartile aRR 4.15 [95% CI 1.31, 13.11], p = 0.02; 3rd quartile aRR 3.41 [95% CI 1.09, 10.69], p = 0.04). Participants with higher variability of BMI had greater risk of PCC (4th quartile aRR 1.29 [95% CI 1.02, 1.64]; p = 0.04). Intraindividual variability of blood pressure (systolic, diastolic) and total circulating cholesterol were not associated with COVID-19 hospitalization or PCC risk (all p > 0.05). From causal mediation analysis, the association between the highest quartiles of BMI variability and PCC was not mediated by hospitalization (p > 0.05).

CONCLUSIONS

Higher intraindividual variability of BMI was associated with COVID-19 hospitalization and PCC risk. Our findings underscore the need for further elucidating mechanisms that explain these associations and importance for consistent maintenance of body weight.

Obesity-compromised immunity in post-COVID-19 condition: a critical control point of chronicity

Post-COVID-19 condition is recognized as a multifactorial disorder, with persistent presence of viral antigens, discordant immunity, delayed viral clearance, and chronic inflammation. Obesity has emerged as an independent risk factor for both SARS-CoV-2 infection and its subsequent sequelae. In this study, we aimed to predict the molecular mechanisms linking obesity and post-COVID-19 distress. Viral antigen-exposed adipose tissues display remarkable levels of viral receptors, facilitating viral entry, deposition, and chronic release of inflammatory mediators and cells in patients. Subsequently, obesity-associated inflammatory insults are predicted to disturb cellular and humoral immunity by triggering abnormal cell differentiation and lymphocyte exhaustion. In particular, the decline in SARS-CoV-2 antibody titers and T-cell exhaustion due to chronic inflammation may account for delayed virus clearance and persistent activation of inflammatory responses. Taken together, obesity-associated defective immunity is a critical control point of intervention against post-COVID-19 progression, particularly in subjects with chronic metabolic distress.

Conference Report: LPMHealthcare Emerging Viruses 2023 (EVOX23): Pandemics-Learning from the Past and Present to Prepare for the Future

The emergence of SARS-CoV-2 has meant that pandemic preparedness has become a major focus of the global scientific community. Gathered in the historic St Edmund Hall college in Oxford, the one-day LPMHealthcare conference on emerging viruses (6 September 2023) sought to review and learn from past pandemics-the current SARS-CoV-2 pandemic and the Mpox outbreak-and then look towards potential future pandemics. This includes an emphasis on monitoring the "traditional" reservoirs of viruses with zoonotic potential, as well as possible new sources of spillover events, e.g., bats, which we are coming into closer contact with due to climate change and the impacts of human activities on habitats. Continued vigilance and investment into creative scientific solutions is required for issues including the long-term physical and psychological effects of COVID-19, i.e., long COVID. The evaluation of current systems, including environmental monitoring, communication (with the public, regulatory authorities, and governments), and training; assessment of the effectiveness of the technologies/assays we have in place currently; and lobbying of the government and the public to work with scientists are all required in order to build trust moving forward. Overall, the SARS-CoV-2 pandemic has shown how many sectors can work together to achieve a global impact in times of crisis.

Vaccine and antiviral drug promise for preventing post-acute sequelae of COVID-19, and their combination for its treatment

Introduction

Most healthy individuals recover from acute SARS-CoV-2 infection, whereas a remarkable number continues to suffer from unexplained symptoms, known as Long COVID or post-acute COVID-19 syndrome (PACS). It is therefore imperative that methods for preventing and treating the onset of PASC be investigated with the utmost urgency.

Methods

A mathematical model of the immune response to vaccination and viral infection with SARS-CoV-2, incorporating immune memory cells, was developed.

Results and discussion

Similar to our previous model, persistent infection was observed by the residual virus in the host, implying the possibility of chronic inflammation and delayed recovery from tissue injury. Pre-infectious vaccination and antiviral medication administered during onset can reduce the acute viral load; however, they show no beneficial effects in preventing persistent infection. Therefore, the impact of these treatments on the PASC, which has been clinically observed, is mainly attributed to their role in preventing severe tissue damage caused by acute viral infections. For PASC patients with persistent infection, vaccination was observed to cause an immediate rapid increase in viral load, followed by a temporary decrease over approximately one year. The former was effectively suppressed by the coadministration of antiviral medications, indicating that this combination is a promising treatment for PASC.

Long COVID as a disease of accelerated biological aging: An opportunity to translate geroscience interventions

It has been four years since long COVID-the protracted consequences that survivors of COVID-19 face-was first described. Yet, this entity continues to devastate the quality of life of an increasing number of COVID-19 survivors without any approved therapy and a paucity of clinical trials addressing its biological root causes. Notably, many of the symptoms of long COVID are typically seen with advancing age. Leveraging this similarity, we posit that Geroscience-which aims to target the biological drivers of aging to prevent age-associated conditions as a group-could offer promising therapeutic avenues for long COVID. Bearing this in mind, this review presents a translational framework for studying long COVID as a state of effectively accelerated biological aging, identifying research gaps and offering recommendations for future preclinical and clinical studies.

Long COVID science, research and policy

Long COVID represents the constellation of post-acute and long-term health effects caused by SARS-CoV-2 infection; it is a complex, multisystem disorder that can affect nearly every organ system and can be severely disabling. The cumulative global incidence of long COVID is around 400 million individuals, which is estimated to have an annual economic impact of approximately $1 trillion-equivalent to about 1% of the global economy. Several mechanistic pathways are implicated in long COVID, including viral persistence, immune dysregulation, mitochondrial dysfunction, complement dysregulation, endothelial inflammation and microbiome dysbiosis. Long COVID can have devastating impacts on individual lives and, due to its complexity and prevalence, it also has major ramifications for health systems and economies, even threatening progress toward achieving the Sustainable Development Goals. Addressing the challenge of long COVID requires an ambitious and coordinated-but so far absent-global research and policy response strategy. In this interdisciplinary review, we provide a synthesis of the state of scientific evidence on long COVID, assess the impacts of long COVID on human health, health systems, the economy and global health metrics, and provide a forward-looking research and policy roadmap.

New-onset sarcoidosis in a patient with long COVID

Long COVID, often following SARS-CoV-2 infection, may stem from sustained inflammation, overlapping with autoimmune diseases like sarcoidosis. Though specific treatments lack, this link could shape future diagnostic and therapeutic methods.

Unveiling dynamics of nitrogen content and selected nitrogen heterocycles in thrombin inhibitors: a ceteris paribus approach

BACKGROUND

Despite the progress in comprehending molecular design principles and biochemical processes associated with thrombin inhibition, there is a crucial need to optimize efforts and curtail the recurrence of synthesis-testing cycles. Nitrogen and N-heterocycles are key features of many anti-thrombin drugs. Hence, a pragmatic analysis of nitrogen and N-heterocycles in thrombin inhibitors is important throughout the drug discovery pipeline. In the present work, the authors present an analysis with a specific focus on understanding the occurrence and distribution of nitrogen and selected N-heterocycles in the realm of thrombin inhibitors.

RESEARCH DESIGN AND METHODS

A dataset comprising 4359 thrombin inhibitors is used to scrutinize various categories of nitrogen atoms such as ring, non-ring, aromatic, and non-aromatic. In addition, selected aromatic and aliphatic N-heterocycles have been analyzed.

RESULTS

The analysis indicates that ~62% of thrombin inhibitors possess five or fewer nitrogen atoms. Substituted N-heterocycles have a high occurrence, like pyrrolidine (23.24%), pyridine (20.56%), piperidine (16.10%), thiazole (9.61%), imidazole (7.36%), etc. in thrombin inhibitors.

CONCLUSIONS

The majority of active thrombin inhibitors contain nitrogen atoms close to 5 and a combination of N-heterocycles like pyrrolidine, pyridine, piperidine, etc. This analysis provides crucial insights to optimize the transformation of lead compounds into potential anti-thrombin inhibitors.

["The idea of rehabilitation will have to be completely rethought for this illness" - Qualitative results of an online survey on patients' experiences with inpatient rehabilitation for post COVID-19 condition (long COVID)]

BACKGROUND

In Germany, an estimated number of 70,000 people diagnosed with long COVID or post-COVID syndrome (PCS) had received inpatient medical rehabilitation by the end of 2022. Due to the heterogeneity of the clinical picture, the variability of interventions and inconsistent endpoints, previous studies on the effectiveness of rehabilitation are of limited value. It therefore remains unclear whether and to what extent rehabilitation measures established for, e.g., pulmonary, cardiovascular, or neurological diseases are suitable for patients with PCS.

OBJECTIVES

To identify the experiences and perspectives of those affected by PCS, in relation to inpatient rehabilitation and to describe patients' values and wishes with respect to evidence-based medicine.

METHODS

In January/February 2023, the German initiative "Long COVID Deutschland" conducted a retrospective online survey (39 closed items, two open answer fields) among adult PCS sufferers on their experiences with inpatient rehabilitation. Recruitment was carried out via social media and websites of patient initiatives. The open answers were analyzed using a structuring and summarizing qualitative content analysis according to Mayring, supplemented by descriptive representations of the distribution of standardized information.

RESULTS

Of 1,191 participants in the survey, 733 used open response formats to additionally explain their experiences and the effects of individual measures on their general condition. 366 (50%) reported that their state of health deteriorated, mainly because of strength or endurance training and too extensive treatment plans. The presence of a post-exertional malaise (PEM) or its insufficient consideration during rehabilitation was described as the main barrier. Recognition and acceptance of individual performance limits, flexible and coordinated individual treatment plans tailored to the patient's limitations, and support in coping with the disease were described as supportive factors. From the participants' perspective, learning strategies to avoid deterioration in their state of health due to overexertion, the so-called pacing, should be the core treatment goal for patients affected by PEM.

DISCUSSION

The results are not statistically representative but ensure systematic insights into the subjective perspectives of those affected, the consideration of which represents one of the three principles of evidence-based medicine. The results show that for PCS patients with PEM, even minimum requirements for rehabilitation measures can lead to overexertion and aggravation.

CONCLUSIONS

Common subject-specific rehabilitation concepts appear to be only partially suitable for dealing with the symptoms and the heterogeneity of the disease. Aims and interventions should be individually adapted, and the focus should be on pacing, disease coping and management. A reliable test for PEM and rehabilitation ability before the start of rehabilitation is needed to ensure safety for those affected. To adequately classify studies on the effectiveness of rehabilitation, risks and side effects should be disclosed.

Long COVID Is Not a Functional Neurologic Disorder

Long COVID is a common sequela of SARS-CoV-2 infection. Data from numerous scientific studies indicate that long COVID involves a complex interaction between pathophysiological processes. Long COVID may involve the development of new diagnosable health conditions and exacerbation of pre-existing health conditions. However, despite this rapidly accumulating body of evidence regarding the pathobiology of long COVID, psychogenic and functional interpretations of the illness presentation continue to be endorsed by some healthcare professionals, creating confusion and inappropriate diagnostic and therapeutic pathways for people living with long COVID. The purpose of this perspective is to present a clinical and scientific rationale for why long COVID should not be considered as a functional neurologic disorder. It will begin by discussing the parallel historical development of pathobiological and psychosomatic/sociogenic diagnostic constructs arising from a common root in neurasthenia, which has resulted in the collective understandings of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and functional neurologic disorder (FND), respectively. We will also review the case definition criteria for FND and the distinguishing clinical and neuroimaging findings in FND vs. long COVID. We conclude that considering long COVID as FND is inappropriate based on differentiating pathophysiologic mechanisms and distinguishing clinical findings.

Postacute Sequelae of SARS-CoV-2 Infection in the Pre-Delta, Delta, and Omicron Eras

BACKGROUND

Postacute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (PASC) can affect many organ systems. However, temporal changes during the coronavirus disease 2019 (Covid-19) pandemic, including the evolution of SARS-CoV-2, may have affected the risk and burden of PASC. Whether the risk and burden of PASC have changed over the course of the pandemic is unclear.

METHODS

We used health records of the Department of Veterans Affairs to build a study population of 441,583 veterans with SARS-CoV-2 infection between March 1, 2020, and January 31, 2022, and 4,748,504 noninfected contemporaneous controls. We estimated the cumulative incidence of PASC at 1 year after SARS-CoV-2 infection during the pre-delta, delta, and omicron eras of the Covid-19 pandemic.

RESULTS

Among unvaccinated persons infected with SARS-CoV-2, the cumulative incidence of PASC during the first year after infection was 10.42 events per 100 persons (95% confidence interval [CI], 10.22 to 10.64) in the pre-delta era, 9.51 events per 100 persons (95% CI, 9.26 to 9.75) in the delta era, and 7.76 events per 100 persons (95% CI, 7.57 to 7.98) in the omicron era (difference between the omicron and pre-delta eras, -2.66 events per 100 persons [95% CI, -2.93 to -2.36]; difference between the omicron and delta eras, -1.75 events per 100 persons [95% CI, -2.08 to -1.42]). Among vaccinated persons, the cumulative incidence of PASC at 1 year was 5.34 events per 100 persons (95% CI, 5.10 to 5.58) during the delta era and 3.50 events per 100 persons (95% CI, 3.31 to 3.71) during the omicron era (difference between the omicron and delta eras, -1.83 events per 100 persons; 95% CI, -2.14 to -1.52). Vaccinated persons had a lower cumulative incidence of PASC at 1 year than unvaccinated persons (difference during the delta era, -4.18 events per 100 persons [95% CI, -4.47 to -3.88]; difference during the omicron era, -4.26 events per 100 persons [95% CI, -4.49 to -4.05]). Decomposition analyses showed 5.23 (95% CI, 4.97 to 5.47) fewer PASC events per 100 persons at 1 year during the omicron era than during the pre-delta and delta eras combined; 28.11% of the decrease (95% CI, 25.57 to 30.50) was attributable to era-related effects (changes in the virus and other temporal effects), and 71.89% (95% CI, 69.50 to 74.43) was attributable to vaccines.

CONCLUSIONS

The cumulative incidence of PASC during the first year after SARS-CoV-2 infection decreased over the course of the pandemic, but the risk of PASC remained substantial even among vaccinated persons who had SARS-CoV-2 infection in the omicron era. (Supported by the Department of Veterans Affairs.).

Developing a clinical-pathological framework of long COVID-related fatigue applied to public safety workers

In the wake of the COVID-19 pandemic, millions worldwide are still struggling with persistent or recurring symptoms known as long COVID. Fatigue is one of the most prevalent symptoms associated with long COVID, and for many it can be debilitating. Understanding the potential pathological processes that link fatigue to long COVID is critical to better guide treatment. Challenges with diagnosis and treatment are reviewed, recognizing that post-COVID fatigue does not always present with corroborating clinical evidence, a situation that is frustrating for both patients and healthcare providers. Firefighters are a group of public safety workers who are particularly impacted by long COVID-related fatigue. Firefighters must be able to engage in strenuous physical activity and deal with demanding psychological situations, both of which may be difficult for those suffering from fatigue. Disruption in public safety worker health can potentially impact community welfare. This review creates a framework to explain the clinical-pathological features of fatigue resulting from long COVID, addresses diagnosis and treatment challenges, and explores the unique impact fatigue may pose for public safety workers and their organizations.

Immune Stimulation with Imiquimod to Best Face SARS-CoV-2 Infection and Prevent Long COVID

Through widespread immunization against SARS-CoV-2 prior to or post-infection, a substantial segment of the global population has acquired both humoral and cellular immunity, and there has been a notable reduction in the incidence of severe and fatal cases linked to this virus and accelerated recovery times for those infected. Nonetheless, a significant demographic, comprising around 20% to 30% of the adult population, remains unimmunized due to diverse factors. Furthermore, alongside those recovered from the infection, there is a subset of the population experiencing persistent symptoms referred to as Long COVID. This condition is more prevalent among individuals with underlying health conditions and immune system impairments. Some Long COVID pathologies stem from direct damage inflicted by the viral infection, whereas others arise from inadequate immune system control over the infection or suboptimal immunoregulation. There are differences in the serum cytokines and miRNA profiles between infected individuals who develop severe COVID-19 or Long COVID and those who control adequately the infection. This review delves into the advantages and constraints associated with employing imiquimod in human subjects to enhance the immune response during SARS-CoV-2 immunization. Restoration of the immune system can modify it towards a profile of non-susceptibility to SARS-CoV-2. An adequate immune system has the potential to curb viral propagation, mitigate symptoms, and ameliorate the severe consequences of the infection.

Interplay between Comorbidities and Long COVID: Challenges and Multidisciplinary Approaches

Long COVID, a name often given to the persistent symptoms following acute SARS-CoV-2 infection, poses a multifaceted challenge for health. This review explores the intrinsic relationship between comorbidities and autoimmune responses in shaping the trajectory of long COVID. Autoantibodies have emerged as significant players in COVID-19 pathophysiology, with implications for disease severity and progression. Studies show immune dysregulation persisting months after infection, marked by activated innate immune cells and high cytokine levels. The presence of autoantibodies against various autoantigens suggests their potential as comorbid factors in long COVID. Additionally, the formation of immune complexes may lead to severe disease progression, highlighting the urgency for early detection and intervention. Furthermore, long COVID is highly linked to cardiovascular complications and neurological symptoms, posing challenges in diagnosis and management. Multidisciplinary approaches, including vaccination, tailored rehabilitation, and pharmacological interventions, are used for mitigating long COVID's burden. However, numerous challenges persist, from evolving diagnostic criteria to addressing the psychosocial impact and predicting disease outcomes. Leveraging AI-based applications holds promise in enhancing patient management and improving our understanding of long COVID. As research continues to unfold, unravelling the complexities of long COVID remains paramount for effective intervention and patient care.

Capturing Home Care Information Management and Communication Processes Among Caregivers of Older Adults: Qualitative Study to Inform Technology Design

BACKGROUND

The demand for complex home care is increasing with the growing aging population and the ongoing COVID-19 pandemic. Family and hired caregivers play a critical role in providing care for individuals with complex home care needs. However, there are significant gaps in research informing the design of complex home care technologies that consider the experiences of family and hired caregivers collectively.

OBJECTIVE

The objective of this study was to explore the health documentation and communication experiences of family and hired caregivers to inform the design and adoption of new technologies for complex home care.

METHODS

The research involved semistructured interviews with 15 caregivers, including family and hired caregivers, each of whom was caring for an older adult with complex medical needs in their home in Ontario, Canada. Due to COVID-19-related protection measures, the interviews were conducted via Teams (Microsoft Corp). The interview guide was informed by the cognitive work analysis framework, and the interview was conducted using storytelling principles of narrative medicine to enhance knowledge. Inductive thematic analysis was used to code the data and develop themes.

RESULTS

Three main themes were developed. The first theme described how participants were continually updating the caregiver team, which captured how health information, including their communication motivations and intentions, was shared among family and hired caregiver participants. The subthemes included binder-based health documentation, digital health documentation, and communication practices beyond the binder. The second theme described how participants were learning to improve care and decision-making, which captured how they acted on information from various sources to provide care. The subthemes included developing expertise as a family caregiver and tailoring expertise as a hired caregiver. The third theme described how participants experienced conflicts within caregiver teams, which captured the different struggles arising from, and the causes of, breakdowns in communication and coordination between family and hired caregiver participants. The subthemes included 2-way communication and trusting the caregiver team.

CONCLUSIONS

This study highlights the health information communication and coordination challenges and experiences that family and hired caregivers face in complex home care settings for older adults. Given the challenges of this work domain, there is an opportunity for appropriate digital technology design to improve complex home care. When designing complex home care technologies, it will be critical to include the overlapping and disparate perspectives of family and hired caregivers collectively providing home care for older adults with complex needs to support all caregivers in their vital roles.

Association of psychiatric disorders with clinical diagnosis of long COVID in US veterans

BACKGROUND

Psychiatric disorders may be a risk factor for long COVID, broadly defined as COVID-19 conditions continuing three months post-acute infection. In US Veterans with high psychiatric burden, we examined associations between psychiatric disorders and clinical diagnosis of long COVID.

METHODS

We conducted a retrospective cohort study using health records from VA patients with a positive SARS-CoV-2 test from February 2020 to February 2023. Generalized linear models estimated associations between any psychiatric disorder and likelihood of subsequent diagnosis with long COVID (i.e. two or more long COVID clinical codes). Models were adjusted for socio-demographic, medical, and behavioral factors. Secondary models examined individual psychiatric disorders and age-stratified associations.

RESULTS

Among 660 217 VA patients with positive SARS-CoV-2 tests, 56.3% had at least one psychiatric disorder diagnosis and 1.4% were diagnosed with long COVID. Individuals with any psychiatric disorder had higher risk for long COVID diagnosis in models adjusted for socio-demographic factors, vaccination status, smoking, and medical comorbidities (relative risk, RR = 1.28, 95% CI 1.21-1.35), with the strongest associations in younger individuals. Considering specific disorders, depressive, anxiety, and stress-related disorders were associated with increased risk for long COVID diagnoses (RRs = 1.36-1.48), but associations were in the opposite direction for substance use and psychotic disorders (RRs = 0.78-0.88).

CONCLUSIONS

Psychiatric disorder diagnoses were associated with increased long COVID diagnosis risk in VA patients, with the strongest associations observed in younger individuals. Improved surveillance, treatment, and prevention for COVID-19 and its long-term sequelae should be considered for individuals with psychiatric conditions.

Predictive value of hematocrit, serum albumin level difference, and fibrinogen-to-albumin ratio for COVID-19-associated acute respiratory failure

Background

Acute respiratory failure is the main clinical manifestation and a major cause of death in patients with COVID-19. However, few reports on its prevention and control have been published because of the need for laboratory predictive indicators. This study aimed to evaluate the predictive value of hematocrit level, serum albumin level difference, and fibrinogen-to-albumin ratio for COVID-19-associated acute respiratory failure.

Material and methods

A total of 120 patients with COVID-19 from the First Affiliated Hospital of Anhui Medical University were selected between December 2022 and March 2023. Patients were divided into acute respiratory failure and non-acute respiratory failure groups and compared patient-related indicators between them using univariate and multivariate logistic regression analyses. Receiver operating characteristic analysis was performed to determine the discrimination accuracy.

Results

In total, 48 and 72 patients were enrolled in the acute respiratory failure and non-acute respiratory failure groups, respectively. The Quick COVID-19 Severity Index scores, fibrinogen-to-albumin ratio, hematocrit and serum albumin level difference, fibrinogen, and hematocrit levels were significantly higher in the acute respiratory failure group than in the non-acute respiratory failure group. A Quick COVID-19 Severity Index >7, fibrinogen-to-albumin ratio >0.265, and hematocrit and serum albumin level difference >12.792 had a 96.14 % positive predictive rate and a 94.06 % negative predictive rate.

Conclusion

Both fibrinogen-to-albumin ratio and hematocrit and serum albumin level difference are risk factors for COVID-19-associated acute respiratory failure. The Quick COVID-19 Severity Index score combined with fibrinogen-to-albumin ratio, and hematocrit and serum albumin level difference predict high and low risks with better efficacy and sensitivity than those of the Quick COVID-19 Severity Index score alone; therefore, these parameters can be used collectively as a risk stratification method for assessing patients with COVID-19.

Design, Synthesis, and Biological Evaluation of 1,2,4-Oxadiazole Derivatives Containing an Aryl Carboxylic Acid Moiety as Potent Sarbecovirus Papain-like Protease Inhibitors

Papain-like protease (PLpro) is a promising therapeutic target for its pivotal role in the life cycle of SARS-CoV-2. A series of 1,2,4-oxadiazole derivatives was designed and synthesized via a ring formation strategy based on SARS-CoV-2 PLpro-GRL0617 complex structure. Systematic structure-activity relationship studies revealed that introducing oxadiazole and aryl carboxylic acid moieties to GRL0617 enhanced the enzymatic inhibition activity, affinity, and deubiquitination capacity toward PLpro. 1,2,4-Oxadiazole compounds 13f and 26r, which had PLpro inhibition activity (IC50 = 1.8 and 1.0 μM) and antiviral activity against SARS-CoV-2 (EC50 = 5.4 and 4.3 μM), exhibited good metabolic stability (t1/2 > 93.2 min) and higher plasma exposure (AUC0-t = 17,380.08 and 24,289.76 ng·h/mL) in mice. Especially, compound 26r with moderate oral bioavailability of 39.1% and potent antiviral activity is worthy of further studies in vivo. Our findings provide a new insight for the discovery of antiviral agents targeting PLpro.

SARS-CoV-2 envelope protein regulates innate immune tolerance

Severe COVID-19 often leads to secondary infections and sepsis that contribute to long hospital stays and mortality. However, our understanding of the precise immune mechanisms driving severe complications after SARS-CoV-2 infection remains incompletely understood. Here, we provide evidence that the SARS-CoV-2 envelope (E) protein initiates innate immune inflammation, via toll-like receptor 2 signaling, and establishes a sustained state of innate immune tolerance following initial activation. Monocytes in this tolerant state exhibit reduced responsiveness to secondary stimuli, releasing lower levels of cytokines and chemokines. Mice exposed to E protein before secondary lipopolysaccharide challenge show diminished pro-inflammatory cytokine expression in the lung, indicating that E protein drives this tolerant state in vivo. These findings highlight the potential of the SARS-CoV-2 E protein to induce innate immune tolerance, contributing to long-term immune dysfunction that could lead to susceptibility to subsequent infections, and uncovers therapeutic targets aimed at restoring immune function following SARS-CoV-2 infection.

Differential Gene Expression in the Upper Respiratory Tract following Acute COVID-19 Infection in Ambulatory Patients That Develop Long COVID

Background: Post-acute sequelae of COVID-19, or long COVID, is a condition characterized by persistent COVID-19 symptoms. As long COVID is defined by clinical criteria after an elapsed period, an opportunity for early intervention may aid in future prophylactic approaches; however, at present, the pathobiological mechanisms are multifactorial. By analyzing early virally infected upper respiratory tract tissue prior to eventual clinical diagnosis, it may be possible to identify biomarkers of altered immune response to facilitate future studies and interventions. Methods: This is a sub-group analysis of samples collected from those with confirmed COVID-19. RNA extraction from nasopharyngeal/mid-turbinate samples, sequencing, and bioinformatic analysis were performed to analyze long COVID and non-long COVID cohorts at day 14 post infection. Differences in mean viral load at various timepoints were analyzed as well as serological data. Results: We identified 26 upregulated genes in patients experiencing long COVID. Dysregulated pathways including complement and fibrinolysis pathways and IL-7 upregulation. Additionally, genes involved in neurotransmission were dysregulated, and the long COVID group had a significantly higher viral load and slower viral clearance. Conclusions: Uncovering early gene pathway abnormalities associated with eventual long COVID diagnosis may aid in early identification. We show that, post acute infection, in situ pathogenic deviations in viral response are associated with patients destined to meet consensus long COVID diagnosis that is entirely dependent on clinical factors. These results identify an important biological temporal window in the natural history of COVID-19 infection and long COVID pathogenesis amenable to testing from standard-of-care upper respiratory tract specimens.

Calcifediol or Corticosteroids in the Treatment of COVID-19: An Observational Study

Medical treatment of coronavirus 19 disease (COVID-19) is a therapeutic challenge. The available data strongly suggest that calcifediol treatment may reduce the severity of COVID-19, and corticosteroids are the treatment of choice worldwide for severe COVID-19. Both have a very similar action profile, and their combined use in patients may modify the contribution of each administered compound.

OBJECTIVE

To evaluate how treatment with calcifediol and/or corticosteroids in medical practice modified the need for ICU admission, death, or poor prognosis of patients hospitalized with COVID-19 during the first outbreaks.

DESIGN, PATIENTS AND SETTING

A retrospective observational cohort study of patients admitted for COVID-19 to the Pneumology Unit of the Hospital Universitario Reina Sofía (Córdoba, Spain).

INTERVENTIONS

Patients were treated with calcifediol or/and corticosteroids with the best available therapy and standard care, according to clinical practice guidelines.

MEASUREMENTS

Admission to the intensive care unit (ICU) or death during hospitalization and poor prognosis.

RESULTS

Seven hundred and twenty-eight patients were included. According to the treatment received, they were included in four groups: calcifediol (n = 68), glucocorticoids (n = 112), both (n = 510), or neither (n = 38). Of the 578 patients treated with calcifediol, 88 were admitted to the ICU (15%), while of the 150 not treated with calcifediol, 39 required ICU admission (26%) (p < 0.01). Among the patients taking calcifediol without glucocorticoids, only 4 of 68 (5.8%) required ICU admission, compared to 84 of 510 (16.5%) treated with both (p = 0.022). Of the 595 patients who had a good prognosis, 568 (82.01%) had received treatment with calcifediol versus the 133 patients with a poor prognosis, of whom 90 (67.66%) had received calcifediol (p < 0.001). This difference was not found for corticosteroids.

INTERPRETATION

The treatment of choice for hospitalized patients with moderate or mild COVID-19 could be calcifediol, not administering corticosteroids, until the natural history of the disease reaches a stage of hyperinflammation.

Promoting equity, diversity, and inclusion in surveys: insights from a patient-engaged study to assess long COVID health-care needs in Brazil

BACKGROUND AND OBJECTIVE

Long COVID (LC) refers to persistent symptoms after acute COVID-19 infection, which may persist for months or years. LC affects millions of people globally, with substantial impacts on quality of life, employment, and social participation. Ensuring access to effective, patient-centered care for LC demands evidence, grounded in inclusive representation of those affected by the condition. Yet survey studies frequently under-represent people with the most disabling disease presentations and racially and socioeconomically marginalized groups. We aimed to describe a patient-engaged approach to developing a survey to inform public LC health care and to assess its implementation in terms of enabling participation by diverse LC patients in Brazil.

METHODS

Survey development was iterative, achieved through an interdisciplinary collaboration among researchers including people living with LC, and grounded in 3 guiding principles: (1) evidence-based; (2) inclusive, intersectional, and patient-centered understanding of chronic illness and research participation; and (3) sensitivity to the context of health-care access.

RESULTS

The product of our collaboration was a longitudinal survey using a questionnaire assessing: LC symptoms; their clinical and functional evolution; and impacts on quality of life, household income, health service access, utilization, and out-of-pocket expenses. We illustrate how we operationalized our 3 principles through survey content, instrument design, and administration. Six hundred fifty-one participants with diverse LC symptoms, demography, and socioeconomic status completed the survey. We successfully included participants experiencing disabling symptoms, Black and mixed race participants, and those with lower education and income.

CONCLUSION

By centering patient experience, our novel, principles-based approach succeeded in promoting equity, diversity, and inclusion in LC survey research. These principles guiding patient-engaged collaboration have broad transferability. We encourage survey researchers working on chronic illness and in other contexts of marginalization and inequality to adopt them.

Post-acute sequelae of SARS-CoV-2 infection (Long COVID) in older adults

Long COVID, also known as PASC (post-acute sequelae of SARS-CoV-2), is a complex infection-associated chronic condition affecting tens of millions of people worldwide. Many aspects of this condition are incompletely understood. Among them is how this condition may manifest itself in older adults and how it might impact the older population. Here, we briefly review the current understanding of PASC in the adult population and examine what is known on its features with aging. Finally, we outline the major gaps and areas for research most germane to older adults.

Challenges and opportunities in long COVID research

Long COVID (LC) is a condition in which patients do not fully recover from the initial SARS-CoV-2 infection but rather have persistent or new symptoms for months to years following the infection. Ongoing research efforts are investigating the pathophysiologic mechanisms of LC and exploring preventative and therapeutic treatment approaches for patients. As a burgeoning area of investigation, LC research can be structured to be more inclusive, innovative, and effective. In this perspective, we highlight opportunities for patient engagement and diverse research expertise, as well as the challenges of developing definitions and reproducible studies. Our intention is to provide a foundation for collaboration and progress in understanding the biomarkers and mechanisms driving LC.

Clinical coding of long COVID in primary care 2020-2023 in a cohort of 19 million adults: an OpenSAFELY analysis

Background

Long COVID is the patient-coined term for the persistent symptoms of COVID-19 illness for weeks, months or years following the acute infection. There is a large burden of long COVID globally from self-reported data, but the epidemiology, causes and treatments remain poorly understood. Primary care is used to help identify and treat patients with long COVID and therefore Electronic Health Records (EHRs) of past COVID-19 patients could be used to help fill these knowledge gaps. We aimed to describe the incidence and differences in demographic and clinical characteristics in recorded long COVID in primary care records in England.

Methods

With the approval of NHS England we used routine clinical data from over 19 million adults in England linked to SARS-COV-2 test result, hospitalisation and vaccination data to describe trends in the recording of 16 clinical codes related to long COVID between November 2020 and January 2023. Using OpenSAFELY, we calculated rates per 100,000 person-years and plotted how these changed over time. We compared crude and adjusted (for age, sex, 9 NHS regions of England, and the dominant variant circulating) rates of recorded long COVID in patient records between different key demographic and vaccination characteristics using negative binomial models.

Findings

We identified a total of 55,465 people recorded to have long COVID over the study period, which included 20,025 diagnoses codes and 35,440 codes for further assessment. The incidence of new long COVID records increased steadily over 2021, and declined over 2022. The overall rate per 100,000 person-years was 177.5 cases in women (95% CI: 175.5-179) and 100.5 in men (99.5-102). The majority of those with a long COVID record did not have a recorded positive SARS-COV-2 test 12 or more weeks before the long COVID record.

Interpretation

In this descriptive study, EHR recorded long COVID was very low between 2020 and 2023, and incident records of long COVID declined over 2022. Using EHR diagnostic or referral codes unfortunately has major limitations in identifying and ascertaining true cases and timing of long COVID.

Funding

This research was supported by the National Institute for Health and Care Research (NIHR) (OpenPROMPT: COV-LT2-0073).