Cellular and molecular biomarkers of long COVID: a scoping review.

BACKGROUND: Long-COVID (LC) encompasses diverse symptoms lasting months after the initial SARS-CoV-2 infection. Symptoms can be debilitating and affect the quality of life of individuals with LC and their families. Although the symptoms of LC are well described, the aetiology of LC remains unclear, and consequently, patients may be underdiagnosed. Identification of LC specific biomarkers is therefore paramount for the diagnosis and clinical management of the syndrome. This scoping review describes the molecular and cellular biomarkers that have been identified to date with potential use for diagnosis or prediction of LC. METHODS: This review was conducted using the Joanna Briggs Institute (JBI) Methodology for Scoping Reviews. A search was executed in the MEDLINE and EMBASE databases, as well as in the grey literature for original studies, published until October 5th, 2022, reporting biomarkers identified in participants with LC symptoms (from all ages, ethnicities, and sex), with a previous infection of SARS-CoV-2. Non-English studies, cross-sectional studies, studies without a control group, and pre-prints were excluded. Two reviewers independently evaluated the studies, extracted population data and associated biomarkers. FINDINGS: 23 cohort studies were identified, involving 2163 LC patients [median age 51.8 years, predominantly female sex (61.10%), white (75%), and non-vaccinated (99%)]. A total of 239 candidate biomarkers were identified, consisting mainly of immune cells, immunoglobulins, cytokines, and other plasma proteins. 19 of the 239 candidate biomarkers identified were evaluated by the authors, by means of receiver operating characteristic (ROC) curves. INTERPRETATION: Diverse cellular and molecular biomarkers for LC have been proposed. Validation of candidate biomarkers in independent samples should be prioritized. Modest reported performance (particularly in larger studies) suggests LC may encompass many distinct aetiologies, which should be explored e.g., by stratifying by symptom clusters and/or sex. FUNDING: Dr. Tebbutt has received funding from the Canadian Institutes of Health Research (177747) to conduct this work. The funding source was not involved in this scoping review, or in the decision to submit this manuscript for publication.

Omicron variants of SARS-CoV-2 and long COVID.

Understanding the epidemiology of long COVID and emerging variants has significant public-health implications as physical interventions and restrictions that help limit viral spread are eased globally. Here, we provide rationales for the necessity of updating current vaccines to improve protection against omicron and emerging variants, as well as more research into understanding the epidemiology and mechanisms of long COVID.

Leave no one behind: inclusion of alpha-1 antitrypsin deficiency patients in COVID-19 vaccine trials.

The coronavirus disease of 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, continues to present an unprecedented challenge worldwide. Emerging evidence suggests that α-1 antitrypsin (A1AT), a circulating protein with protective effects on the lung and other vital organs, plays a critical role in preventing SARS-CoV-2 infection and may be a promising therapeutic option for patients with COVID-19. A1AT deficiency (AATD) is characterized by dysfunctional or insufficient levels of A1AT. Recently, we have proposed that AATD patients are a vulnerable population for COVID-19. Patients with AATD may derive limited benefit from the current COVID-19 vaccines and continue to rely on conventional medical therapy and behavioral adaptations to mitigate the risk of infection. Unfortunately, this population has not been included in the COVID-19 vaccine clinical trials and studies have yet to characterize the safety, immunogenicity, and ultimately, the efficacy of COVID-19 vaccines for AATD patients. Re-evaluation of the COVID-19 vaccine safety and immunogenicity will further promote informed decision-making for vaccination in AATD individuals and contribute to reduce morbidity and mortality from COVID-19 infection.

Alpha-1 Antitrypsin for COVID-19 Treatment: Dual Role in Antiviral Infection and Anti-Inflammation.

Many drugs have been approved for clinical trials for the treatment of COVID-19 disease, focusing on either antiviral or anti-inflammatory approaches. Combining antiviral and anti-inflammatory drugs or therapies together may be more effective. Human alpha-1 antitrypsin (A1AT) is a blood circulating glycoprotein that is best known as a protease inhibitor. It has been used to treat emphysema patients with A1AT deficiency for decades. We and others have demonstrated its role in reducing acute lung injury by inhibiting inflammation, cell death, coagulation, and neutrophil elastase activation. Recently, A1AT has been found to inhibit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection by inhibiting transmembrane serine protease 2 (TMPRSS2), a protease involved in the entry of SARS-CoV-2 into host cells. This dual role of both antiviral infection and anti-inflammation makes A1AT a unique and excellent candidate for COVID-19 treatment. Three clinical trials of A1AT for COVID-19 treatment have recently been approved in several countries. It is important to determine whether A1AT can prevent the progress from moderate to severe lung injury and eventually to be used to treat COVID-19 patients with acute respiratory distress syndrome.