Long COVID: Clinical Findings, Pathology, and Endothelial Molecular Mechanisms

Multicentre retrospective detection of nailfold videocapillaroscopy abnormalities in long covid patients

BACKGROUND

SARS-CoV-2 induces acute non-specific endothelial/microvascular alterations that have been identified by nailfold videocapillaroscopy (NVC). Details on NVC abnormalities in long covid (LC) patients (pts) are unknown.

METHODS

LC pts without and with systemic sclerosis (non-SSc-LC and SSc-LC), recovered COVID-19 (RC) pts that did not develop LC and healthy matched control subjects (CNT) that underwent NVC examinations were evaluated in a multicentre national study from the Capillaroscopy and Microcirculation in Rheumatic Diseases Study Group of the Italian Society of Rheumatology. Retrospective collection was performed for demographic data, course of SARS-CoV-2 infection, comorbidities, concomitant drugs. NVC alterations were quantified by validated scores. Pre-COVID-19 and post-COVID-19 microvascular status was analysed by NVC.

RESULTS

62 non-SSc-LC pts (49 female/13 male, 51±16 years old), 24 SSc-LC pts (21 female/3 male, 59±17 years old), 23 RC pts (18 female/5 male, 51±18 years old) and 84 CNT (68 female/16 male, 52±12 years old) were analysed. Non-SSc-LC pts showed significantly more dilated capillaries (p<0.01, p multivariate<0.01), microhaemorrhages (p=0.01, p multivariate<0.05), abnormal shapes (p<0.05, p multivariate<0.05) than CNT and of note, lower mean capillary number per linear millimetre (p<0.01, p multivariate<0.01) than both RC pts and CTN (p<0.01, p multivariate<0.05).Of highest interest, 16 non-SSc-LC pts showed statistically significantly more dilated capillaries (p<0.05) and microhaemorrhages (p<0.05) in NVC examinations after COVID-19, compared with pre-COVID-19 status.Similarly, SSc-LC pts (24) showed significantly lower capillary density (p=0.01) and more dilated capillaries (p<0.01) in NVC examinations after COVID-19, compared with pre-COVID-19 status.

CONCLUSIONS

LC pts show more microvascular alterations at NVC as compared with RC patients and CNT, which may contribute to the pathogenesis of persistent organ/systems dysfunction.

Changes in cerebrovascular reactivity within functional networks in older adults with long-COVID

Introduction

Cognitive symptoms are reported in the vast majority of individuals with long-COVID and there is growing support to suggest neurovascular mechanisms may play a role. Older adults are at increased risk for developing complications associated with COVID-19, including heightened risk for cognitive decline. Cerebrovascular Reactivity (CVR), a marker of neurovascular health, has been linked to age related cognitive decline and may play a role in long-COVID, however, this has not yet been explored.

Methods

The present study examined group differences in CVR in 31 older adults with long-COVID compared to 31 cognitively unimpaired older adults without long-COVID symptoms. Follow up analyses were conducted to examine how CVR was associated with both subjective cognitive symptoms and neuropsychological (NP) test performance. A subject-specific approach, Distribution-Corrected Z-scores (DisCo-Z), was used.

Results

Analyses revealed the long-COVID group demonstrated significantly greater incidence of extreme CVR clusters within the brain (>100 voxels) and within functional networks thought to drive attention and executive function. Extreme positive CVR clusters were positively associated with greater number of subjective cognitive symptoms and negatively correlated with NP performance.

Discussion

These findings are among the first to provide a link between cognitive functioning in long-COVID and neurovascular changes relevant for aging and mechanistic studies of long-COVID.

Long COVID Research, 2020-2024: A PubMed-Based Bibliometric Analysis

Long COVID is a SARS-CoV-2 infection-associated chronic condition with great potential to impact health and socioeconomic outcomes. The research efforts to face the challenges related to long COVID have resulted in a substantial amount of publications, which warrants the need for bibliometric profiling. This is a large-scale PubMed-based bibliometric analysis of more than 390,000 COVID-19 publications. The overall aim was to update the profile of long COVID publications in comparison with the rest of the COVID-19 scientific literature through December 2024. The estimated proportion of long COVID publications was relatively low (2.3% of all COVID-19 publications), although the cumulative frequency (n = 8928) continues to pose a challenge for proper information management. Currently, "treatment" and "mechanism" appear to be the most predominant research topics in the long COVID literature. Interestingly, this evaluation revealed a distinctive profile of the long COVID literature, with a clear preponderance of "case report" and "mechanism" research topics when compared with other COVID-19 publications. This evaluation also identified and ranked the most prolific scientific journals in the production of long COVID-related publications. This study may improve the visibility of long COVID research and contribute to the management of the growing scientific knowledge on long COVID.

SARS-CoV-2 evolution has increased resistance to monoclonal antibodies and first-generation COVID-19 vaccines: Is there a future therapeutic role for soluble ACE2 receptors for COVID-19?

COVID-19 has caused calamitous health, economic and societal consequences. Although several COVID-19 vaccines have received full authorization for use, global deployment has faced political, financial and logistical challenges. The efficacy of first-generation COVID-19 vaccines is waning and breakthrough infections are allowing ongoing transmission and evolution of SARS-CoV-2. Furthermore, COVID-19 vaccine efficacy relies on a functional immune system. Despite receiving three primary doses and three or more heterologous boosters, some immunocompromised patients may not be adequately protected by COVID-19 vaccines and remain vulnerable to severe disease. The evolution of new SARS-CoV-2 variants has also resulted in the rapid obsolescence of monoclonal antibodies. Convalescent plasma from COVID-19 survivors has produced inconsistent results. New drugs such as Paxlovid (nirmatrelvir/ritonavir) are beyond the reach of low- and middle-income countries. With widespread use of Paxlovid, it is likely nirmatrelvir-resistant clades of SARS-CoV-2 will emerge in the future. There is thus an urgent need for new effective anti-SARS-CoV-2 treatments. The in vitro efficacy of soluble ACE2 against multiple SARS-CoV-2 variants including omicron (B.1.1.529), was recently described using a competitive ELISA assay as a surrogate marker for virus neutralization. This indicates soluble wild-type ACE2 receptors are likely to be resistant to viral evolution. Nasal and inhaled treatment with soluble ACE2 receptors has abrogated severe disease in animal models of COVID-19. There is an urgent need for clinical trials of this new class of antiviral therapeutics, which could complement vaccines and Paxlovid.

Diaphragmatic strengthening exercises for patients with post COVID-19 condition after mild-to-moderate acute COVID-19 infection: a randomized controlled study

OBJECTIVE

To assess the clinical effects of incentive spirometry (IS) and diaphragmatic breathing (DB) in patients with post COVID-19 condition and diaphragmatic dysfunction as compared with the standard care alone.

METHODS

The present longitudinal randomized study included 60 patients with post COVID-19 condition and diaphragmatic dysfunction. Patients were equally randomized to receive standard care plus IS (G1), standard care plus DB (G2) or standard care alone (G3) for 8 weeks. The primary outcome is clinical improvement as evaluated by the modified Medical Research Council (mMRC) dyspnoea scale.

RESULTS

Comparison between the studied groups revealed significant improvement in G1 and G2 in all parameters at the end of follow-up. However, no significant improvement was found in G3. At the end of follow-up, 15 patients (75.0%) in G1, 11 patients (55.0%) in G2, and 3 patients (15.0%) in G3 showed improvement on the mMRC dyspnoea scale. Multivariate logistic regression analysis identified mild acute COVID-19 infection (p = 0.009), use of IS (p < 0.001), and use of DB (p = 0.023) as significant predictors of improvement on the mMRC dyspnoea scale.

CONCLUSIONS

IS or DB training in addition to the standard care in post COVID-19 condition was associated with better clinical improvement as compared with the standard care alone.

Long COVID or Post-COVID-19 Condition: Past, Present and Future Research Directions

The presence of symptoms after an acute SARS-CoV-2 infection (long-COVID) has become a worldwide healthcare emergency but remains underestimated and undertreated due to a lack of recognition of the condition and knowledge of the underlying mechanisms. In fact, the prevalence of post-COVID symptoms ranges from 50% during the first months after the infection up to 20% two-years after. This perspective review aimed to map the existing literature on post-COVID symptoms and to identify gaps in the literature to guide the global effort toward an improved understanding of long-COVID and suggest future research directions. There is a plethora of symptomatology that can be due to COVID-19; however, today, there is no clear classification and definition of this condition, termed long-COVID or post-COVID-19 condition. The heterogeneity in the symptomatology has led to the presence of groups/clusters of patients, which could exhibit different risk factors and different mechanisms. Viral persistence, long-lasting inflammation, immune dysregulation, autoimmune reactions, reactivation of latent infections, endothelial dysfunction and alteration in gut microbiota have been proposed as potential mechanisms explaining the complexity of long-COVID. In such an equation, viral biology (e.g., re-infections, SARS-CoV-2 variants), host biology (e.g., genetics, epigenetics) and external factors (e.g., vaccination) should be also considered. These various factors will be discussed in the current perspective review and future directions suggested.