Limited recovery from post-acute sequelae of SARS-CoV-2 at 8 months in a prospective cohort

Improvement of immune dysregulation in individuals with long COVID at 24-months following SARS-CoV-2 infection

This study investigates the humoral and cellular immune responses and health-related quality of life measures in individuals with mild to moderate long COVID (LC) compared to age and gender matched recovered COVID-19 controls (MC) over 24 months. LC participants show elevated nucleocapsid IgG levels at 3 months, and higher neutralizing capacity up to 8 months post-infection. Increased spike-specific and nucleocapsid-specific CD4+ T cells, PD-1, and TIM-3 expression on CD4+ and CD8+ T cells were observed at 3 and 8 months, but these differences do not persist at 24 months. Some LC participants had detectable IFN-γ and IFN-β, that was attributed to reinfection and antigen re-exposure. Single-cell RNA sequencing at the 24 month timepoint shows similar immune cell proportions and reconstitution of naïve T and B cell subsets in LC and MC. No significant differences in exhaustion scores or antigen-specific T cell clones are observed. These findings suggest resolution of immune activation in LC and return to comparable immune responses between LC and MC over time. Improvement in self-reported health-related quality of life at 24 months was also evident in the majority of LC (62%). PTX3, CRP levels and platelet count are associated with improvements in health-related quality of life.

Intrinsic factors behind long COVID: IV. Hypothetical roles of the SARS-CoV-2 nucleocapsid protein and its liquid-liquid phase separation

When the SARS-CoV-2 virus infects humans, it leads to a condition called COVID-19 that has a wide spectrum of clinical manifestations, from no symptoms to acute respiratory distress syndrome. The virus initiates damage by attaching to the ACE-2 protein on the surface of endothelial cells that line the blood vessels and using these cells as hosts for replication. Reactive oxygen species levels are increased during viral replication, which leads to oxidative stress. About three-fifths (~60%) of the people who get infected with the virus eradicate it from their body after 28 days and recover their normal activity. However, a large fraction (~40%) of the people who are infected with the virus suffer from various symptoms (anosmia and/or ageusia, fatigue, cough, myalgia, cognitive impairment, insomnia, dyspnea, and tachycardia) beyond 12 weeks and are diagnosed with a syndrome called long COVID. Long-term clinical studies in a group of people who contracted SARS-CoV-2 have been contrasted with a noninfected matched group of people. A subset of infected people can be distinguished by a set of cytokine markers to have persistent, low-grade inflammation and often self-report two or more bothersome symptoms. No medication can alleviate their symptoms efficiently. Coronavirus nucleocapsid proteins have been investigated extensively as potential drug targets due to their key roles in virus replication, among which is their ability to bind their respective genomic RNAs for incorporation into emerging virions. This review highlights basic studies of the nucleocapsid protein and its ability to undergo liquid-liquid phase separation. We hypothesize that this ability of the nucleocapsid protein for phase separation may contribute to long COVID. This hypothesis unlocks new investigation angles and could potentially open novel avenues for a better understanding of long COVID and treating this condition.

Long-lasting cognitive effects of COVID-19: is there a role of BDNF?

Coronavirus disease 2019 (COVID-19) affects numerous systems of the body during the illness, and there have been long-lasting effects. BDNF plays an important role in synaptic plasticity and synaptic communication. According to the inclusion and exclusion criteria, 54 patients who had COVID-19 infection participated in this study. Thirty-six age-, sex-, body mass index (BMI)-, education level- and smoking status-matched healthy controls were included in the present study. All participants were individually administered the Stroop test and Visual Aural Digit Span Test Form B (VADS-B). Serum BDNF levels were measured by ELISA. Stroop test word reading spontaneous correction number and reading time, word color saying wrong number, spontaneous correction number and reading time, box color speaking spontaneous correction number and reading time, Stroop interference and speed factor duration were significantly higher in the COVID-19 group than in the control group. All scores of the VADS-B test were found to be significantly lower in the COVID-19 group. The mean serum BDNF levels were found to be 10.9 ± 6.9 ng/ml in the COVID-19 group and 12.8 ± 6.4 ng/ml in the healthy control group. Two-way ANOVA showed that the serum mean BDNF level was significantly lower in the COVID-19 group than in the control group. Gender had a significant effect on BDNF levels (F = 12.21; p = 0.008). The present study is the first to demonstrate the association between the role of serum BDNF and cognitive decline in patients with COVID-19 infection. Additionally, there is a significant role of male gender in terms of lower BDNF level and cognitive decline.

A systematic review and meta-analysis of long COVID symptoms

BACKGROUND

Ongoing symptoms or the development of new symptoms following a SARS-CoV-2 diagnosis has caused a complex clinical problem known as "long COVID" (LC). This has introduced further pressure on global healthcare systems as there appears to be a need for ongoing clinical management of these patients. LC personifies heterogeneous symptoms at varying frequencies. The most complex symptoms appear to be driven by the neurology and neuropsychiatry spheres.

METHODS

A systematic protocol was developed, peer reviewed, and published in PROSPERO. The systematic review included publications from the 1st of December 2019-30th June 2021 published in English. Multiple electronic databases were used. The dataset has been analyzed using a random-effects model and a subgroup analysis based on geographical location. Prevalence and 95% confidence intervals (CIs) were established based on the data identified.

RESULTS

Of the 302 studies, 49 met the inclusion criteria, although 36 studies were included in the meta-analysis. The 36 studies had a collective sample size of 11,598 LC patients. 18 of the 36 studies were designed as cohorts and the remainder were cross-sectional. Symptoms of mental health, gastrointestinal, cardiopulmonary, neurological, and pain were reported.

CONCLUSIONS

The quality that differentiates this meta-analysis is that they are cohort and cross-sectional studies with follow-up. It is evident that there is limited knowledge available of LC and current clinical management strategies may be suboptimal as a result. Clinical practice improvements will require more comprehensive clinical research, enabling effective evidence-based approaches to better support patients.

Fatigue outcomes following COVID-19: a systematic review and meta-analysis

OBJECTIVES

Fatigue is a pervasive clinical symptom in coronaviruses and may continue beyond the acute phase, lasting for several months or years. This systematic review and meta-analysis aimed to incorporate the current evidence for postinfection fatigue among survivors of SARS-CoV-2 and investigate associated factors.

METHODS

Embase, PsyINFO, Medline, CINAHL, CDSR, Open Grey, BioRxiv and MedRxiv were systematically searched from January 2019 to December 2021. Eligible records included all study designs in English. Outcomes were fatigue or vitality in adults with a confirmed diagnosis of SARS-CoV-2 measured at >30 days post infection. Non-confirmed cases were excluded. JBI risk of bias was assessed by three reviewers. Random effects model was used for the pooled proportion with 95% CIs. A mixed effects meta-regression of 35 prospective articles calculated change in fatigue overtime. Subgroup analyses explored specific group characteristics of study methodology. Heterogeneity was assessed using Cochran's Q and I2 statistic. Egger's tests for publication bias.

RESULTS

Database searches returned 14 262 records. Following deduplication and screening, 178 records were identified. 147 (n=48 466 participants) were included for the meta-analyses. Pooled prevalence was 41% (95% CI: 37% to 45%, k=147, I2=98%). Fatigue significantly reduced over time (-0.057, 95% CI: -107 to -0.008, k=35, I2=99.3%, p=0.05). A higher proportion of fatigue was found in studies using a valid scale (51%, 95% CI: 43% to 58%, k=36, I2=96.2%, p=0.004). No significant difference was found for fatigue by study design (p=0.272). Egger's test indicated publication bias for all analyses except valid scales. Quality assessments indicated 4% at low risk of bias, 78% at moderate risk and 18% at high risk. Frequently reported associations were female gender, age, physical functioning, breathlessness and psychological distress.

CONCLUSION

This study revealed that a significant proportion of survivors experienced fatigue following SARS-CoV-2 and their fatigue reduced overtime. Non-modifiable factors and psychological morbidity may contribute to ongoing fatigue and impede recovery.

PROSPERO REGISTRATION NUMBER

CRD42020201247.

A Prospect to Ameliorate Affective Symptoms and to Enhance Cognition in Long COVID Using Auricular Transcutaneous Vagus Nerve Stimulation

Long COVID, the postviral disorder caused by COVID-19, is expected to become one of the leading causes of disability in Europe. The cognitive consequences of long COVID have been described as "brain fog" and characterized by anxiety and depression, and by cognitive deficits. Long COVID is assumed to be a complex condition arising from multiple causes, including persistent brainstem dysfunction and disrupted vagal signaling. We recommend the potential application of auricular transcutaneous vagus nerve stimulation (atVNS) as an ADD-ON instrument to compensate for the cognitive decline and to ameliorate affective symptoms caused by long COVID. This technique enhances vagal signaling by directly activating the nuclei in the brainstem, which are hypoactive in long COVID to enhance mood and to promote attention, memory, and cognitive control-factors affected by long COVID. Considering that atVNS is a non-pharmacological intervention, its ADD-ON to standard pharmaceutical agents will be useful for non-responders, making of this method a suitable tool. Given that atVNS can be employed as an ecological momentary intervention (EMI), we outline the translational advantages of atVNS in the context of accelerating the cognitive and affective recovery from long COVID.

Emerging Roles of Type-I Interferons in Neuroinflammation, Neurological Diseases, and Long-Haul COVID

Interferons (IFNs) are pleiotropic cytokines originally identified for their antiviral activity. IFN-α and IFN-β are both type I IFNs that have been used to treat neurological diseases such as multiple sclerosis. Microglia, astrocytes, as well as neurons in the central and peripheral nervous systems, including spinal cord neurons and dorsal root ganglion neurons, express type I IFN receptors (IFNARs). Type I IFNs play an active role in regulating cognition, aging, depression, and neurodegenerative diseases. Notably, by suppressing neuronal activity and synaptic transmission, IFN-α and IFN-β produced potent analgesia. In this article, we discuss the role of type I IFNs in cognition, neurodegenerative diseases, and pain with a focus on neuroinflammation and neuro-glial interactions and their effects on cognition, neurodegenerative diseases, and pain. The role of type I IFNs in long-haul COVID-associated neurological disorders is also discussed. Insights into type I IFN signaling in neurons and non-neuronal cells will improve our treatments of neurological disorders in various disease conditions.

Evaluation of serological assays for SARS-CoV-2 antibody testing from dried blood spots collected from cohorts with prior SARS-CoV-2 infection

Background

Dried blood spot (DBS) specimens are a useful serosurveillance tool particularly in hard-to-reach populations but their application for detecting SARS-CoV-2 infection is poorly characterised.

Objectives

To compare detection of naturally acquired SARS-CoV-2 antibodies in paired DBS and serum specimens using commercially available serological immunoassays.

Study Design

Specimens were collected through St Vincent's Hospital observational post COVID-19 cohort study (ADAPT). Laboratory spotted DBS from venepuncture were initially tested on seven assays, a DBS validation completed on three with clinically collected fingerstick DBSs tested on one.

Results

Sensitivity for Euroimmun nucleocapsid (NCP) IgG ELISA from laboratory spotted DBS (n=145), Euroimmun spike, IgG ELISA from laboratory spotted DBS (n=161), and Binding Site total antibody ELISA from clinically collected fingerstick DBS (n=391) was 100% (95% CI: 95.8-100%), 100% (95% CI: 95.8-100%) and 92.9% (95% CI: 89.5-95.5%), respectively. Specificity was 66.2% (95% CI: 53.6-77.0%), 96% (95% CI: 88.7-99.1%) and 98.8% (95% CI: 93.3-99.9%), respectively. All three assays’ results displayed a strong positive correlation between DBS compared to paired serum.

Conclusions

The Binding Site™ spike total antibody and Euroimmun™ spike IgG ELISAs provided good analytical performance, demonstrating that DBS specimens could facilitate specimen collection in the epidemiological surveillance of SARS-CoV-2 infection. This is highly applicable in populations and settings where venepuncture is problematic (including community based regional/remote settings, nursing homes, prisons, and schools).

Immune determinants of chronic sequelae after respiratory viral infection

The acute effects of various respiratory viral infections have been well studied, with extensive characterization of the clinical presentation as well as viral pathogenesis and host responses. However, over the course of the recent COVID-19 pandemic, the incidence and prevalence of chronic sequelae after acute viral infections have become increasingly appreciated as a serious health concern. Post-acute sequelae of COVID-19, alternatively described as “long COVID-19,” are characterized by symptoms that persist for longer than 28 days after recovery from acute illness. Although there exists substantial heterogeneity in the nature of the observed sequelae, this phenomenon has also been observed in the context of other respiratory viral infections including influenza virus, respiratory syncytial virus, rhinovirus, severe acute respiratory syndrome coronavirus, and Middle Eastern respiratory syndrome coronavirus. In this Review, we discuss the various sequelae observed following important human respiratory viral pathogens and our current understanding of the immunological mechanisms underlying the failure of restoration of homeostasis in the lung.

Cytokine Profiles Associated With Acute COVID-19 and Long COVID-19 Syndrome

The duration and severity of COVID-19 are related to age, comorbidities, and cytokine synthesis. This study evaluated the impact of these factors on patients with clinical presentations of COVID-19 in a Brazilian cohort. A total of 317 patients diagnosed with COVID-19 were included; cases were distributed according to clinical status as severe (n=91), moderate (n=56) and mild (n=170). Of these patients, 92 had acute COVID-19 at sample collection, 90 had already recovered from COVID-19 without sequelae, and 135 had sequelae (long COVID syndrome). In the acute COVID-19 group, patients with the severe form had higher IL-6 levels (p=0.0260). In the post-COVID-19 group, there was no significant difference in cytokine levels between groups with different clinical conditions. In the acute COVID-19 group, younger patients had higher levels of TNF-α, and patients without comorbidities had higher levels of TNF-α, IL-4 and IL-2 (p<0.05). In contrast, patients over age 60 with comorbidities had higher levels of IL-6. In the post-COVID-19 group, subjects with long COVID-19 had higher levels of IL-17 and IL-2 (p<0.05), and subjects without sequelae had higher levels of IL-10, IL-6 and IL- 4 (p<0.05). Our results suggest that advanced age, comorbidities and elevated serum IL-6 levels are associated with severe COVID-19 and are good markers to differentiate severe from mild cases. Furthermore, high serum levels of IL-17 and IL-2 and low levels of IL-4 and IL-10 appear to constitute a cytokine profile of long COVID-19, and these markers are potential targets for COVID-19 treatment and prevention strategies.

Markers of fungal translocation are elevated during post-acute sequelae of SARS-CoV-2 and induce NF-κB signaling

Long COVID, a type of post-acute sequelae of SARS-CoV-2 (PASC), has been associated with sustained elevated levels of immune activation and inflammation. However, the mechanisms that drive this inflammation remain unknown. Inflammation during acute coronavirus disease 2019 could be exacerbated by microbial translocation (from the gut and/or lung) to blood. Whether microbial translocation contributes to inflammation during PASC is unknown. We did not observe a significant elevation in plasma markers of bacterial translocation during PASC. However, we observed higher levels of fungal translocation — measured as β-glucan, a fungal cell wall polysaccharide — in the plasma of individuals experiencing PASC compared with those without PASC or SARS-CoV-2–negative controls. The higher β-glucan correlated with higher inflammation and elevated levels of host metabolites involved in activating N-methyl-d-aspartate receptors (such as metabolites within the tryptophan catabolism pathway) with established neurotoxic properties. Mechanistically, β-glucan can directly induce inflammation by binding to myeloid cells (via Dectin-1) and activating Syk/NF-κB signaling. Using a Dectin-1/NF-κB reporter model, we found that plasma from individuals experiencing PASC induced higher NF-κB signaling compared with plasma from negative controls. This higher NF-κB signaling was abrogated by piceatannol (Syk inhibitor). These data suggest a potential targetable mechanism linking fungal translocation and inflammation during PASC.

The Pathophysiology of Long COVID throughout the Renin-Angiotensin System

COVID-19 has expanded across the world since its discovery in Wuhan (China) and has had a significant impact on people’s lives and health. Long COVID is a term coined by the World Health Organization (WHO) to describe a variety of persistent symptoms after acute SARS-CoV-2 infection. Long COVID has been demonstrated to affect various SARS-CoV-2-infected persons, independently of the acute disease severity. The symptoms of long COVID, like acute COVID-19, consist in the set of damage to various organs and systems such as the respiratory, cardiovascular, neurological, endocrine, urinary, and immune systems. Fatigue, dyspnea, cardiac abnormalities, cognitive and attention impairments, sleep disturbances, post-traumatic stress disorder, muscle pain, concentration problems, and headache were all reported as symptoms of long COVID. At the molecular level, the renin-angiotensin system (RAS) is heavily involved in the pathogenesis of this illness, much as it is in the acute phase of the viral infection. In this review, we summarize the impact of long COVID on several organs and tissues, with a special focus on the significance of the RAS in the disease pathogenesis. Long COVID risk factors and potential therapy approaches are also explored.

Immunological dysfunction persists for 8 months following initial mild-to-moderate SARS-CoV-2 infection

A proportion of patients surviving acute coronavirus disease 2019 (COVID-19) infection develop post-acute COVID syndrome (long COVID (LC)) lasting longer than 12 weeks. Here, we studied individuals with LC compared to age- and gender-matched recovered individuals without LC, unexposed donors and individuals infected with other coronaviruses. Patients with LC had highly activated innate immune cells, lacked naive T and B cells and showed elevated expression of type I IFN (IFN-β) and type III IFN (IFN-λ1) that remained persistently high at 8 months after infection. Using a log-linear classification model, we defined an optimal set of analytes that had the strongest association with LC among the 28 analytes measured. Combinations of the inflammatory mediators IFN-β, PTX3, IFN-γ, IFN-λ2/3 and IL-6 associated with LC with 78.5-81.6% accuracy. This work defines immunological parameters associated with LC and suggests future opportunities for prevention and treatment.

"LONG COVID"-A hypothesis for understanding the biological basis and pharmacological treatment strategy

Infection of humans with SARS‐CoV‐2 virus causes a disease known colloquially as “COVID‐19” with symptoms ranging from asymptomatic to severe pneumonia. Initial pathology is due to the virus binding to the ACE‐2 protein on endothelial cells lining blood vessels and entering these cells in order to replicate. Viral replication causes oxidative stress due to elevated levels of reactive oxygen species. Many (~60%) of the infected people appear to have eliminated the virus from their body after 28 days and resume normal activity. However, a significant proportion (~40%) experience a variety of symptoms (loss of smell and/or taste, fatigue, cough, aching pain, “brain fog,” insomnia, shortness of breath, and tachycardia) after 12 weeks and are diagnosed with a syndrome named “LONG COVID.” Longitudinal clinical studies in a group of subjects who were infected with SARS‐CoV‐2 have been compared to a non‐infected matched group of subjects. A cohort of infected subjects can be identified by a battery of cytokine markers to have persistent, low level grade of inflammation and often self‐report two or more troubling symptoms. There is no drug that will relieve their symptoms effectively. It is hypothesized that drugs that activate the intracellular transcription factor, nuclear factor erythroid‐derived 2‐like 2 (NRF2) may increase the expression of enzymes to synthesize the intracellular antioxidant, glutathione that will quench free radicals causing oxidative stress. The hormone melatonin has been identified as an activator of NRF2 and a relatively safe chemical for most people to ingest chronically. Thus, it is an option for consideration of re‐purposing studies in “LONG COVID” subjects experiencing insomnia, depression, fatigue, and “brain fog” but not tachycardia. Appropriately designed clinical trials are required to evaluate melatonin.