Summary

On 11 March 2020, the World Health Organization declared COVID-19 a global pandemic, and the disease now affects nearly every country and region. Caused by SARS-CoV-2, COVID-19 continues nearly 18 months later to present significant challenges to health systems and public health in both hemispheres, as well as the economies of every country. The morbidity and mortality of the infection caused by SARS-CoV-2 has been significant, and various waves of disease outbreaks initially overwhelmed many hospitals and clinics and continue to do so in many countries. This influences everyone, and public health countermeasures have been dramatic in terms of their impact on employment, social systems, and mental health. This entry collection aims to gather diverse fields about COVID-19, including in epidemiology, public health, medicine, genetics, systems biology, informatics, data science, engineering, sociology, anthropology, nursing, environmental studies, statistics, and psychology.

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Entries
Topic Review
Pandemic Nursing Framework for Nursing Homes During COVID-19
Nurses have played a vital role in the fight against COVID-19 by ensuring continuity in patient care and demonstrating clinical leadership in pandemic efforts. The pandemic nursing measures can be broadly classified into four groups: (1) infection surveillance and containment measures; (2) ensuring continuity in clinical care and operational support; (3) resource and administrative coordination; and (4) staff training and development. 
  • 1.5K
  • 29 Dec 2021
Topic Review
Development of SARS-CoV-2 Variants
A novel coronavirus (SARS-CoV-2) emerged towards the end of 2019 that caused a severe respiratory disease in humans called COVID-19. It led to a pandemic with a high rate of morbidity and mortality that is ongoing and threatening humankind. Most of the mutations occurring in SARS-CoV-2 are synonymous or deleterious, but a few of them produce improved viral functions. The first known mutation associated with higher transmissibility, D614G, was detected in early 2020. Since then, the virus has evolved; new mutations have occurred, and many variants have been described. Depending on the genes affected and the location of the mutations, they could provide altered infectivity, transmissibility, or immune escape. To date, mutations that cause variations in the SARS-CoV-2 spike protein have been among the most studied because of the protein’s role in the initial virus–cell contact and because it is the most variable region in the virus genome. Some concerning mutations associated with an impact on viral fitness have been described in the Spike protein, such as D614G, N501Y, E484K, K417N/T, L452R, and P681R, among others. To understand the impact of the infectivity and antigenicity of the virus, the mutation landscape of SARS-CoV-2 has been under constant global scrutiny. The virus variants are defined according to their origin, their genetic profile (some characteristic mutations prevalent in the lineage), and the severity of the disease they produce, which determines the level of concern. If they increase fitness, new variants can outcompete others in the population. The Alpha variant was more transmissible than previous versions and quickly spread globally. The Beta and Gamma variants accumulated mutations that partially escape the immune defenses and affect the effectiveness of vaccines. Nowadays, the Delta variant, identified around March 2021, has spread and displaced the other variants, becoming the most concerning of all lineages that have emerged. The Delta variant has a particular genetic profile, bearing unique mutations, such as T478K in the spike protein and M203R in the nucleocapsid. This entry summarizes the current knowledge of the different mutations that have appeared in SARS-CoV-2, mainly on the spike protein. It analyzes their impact on the protein function and, subsequently, on the level of concern of different variants and their importance in the ongoing pandemic. 
  • 1.5K
  • 28 Dec 2021
Topic Review
Aryl Hydrocarbon Receptor and COVID-19
There is an under-recognized role of the aryl hydrocarbon receptor (AhR) in co-ordinating the entry and pathophysiology of the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) that underpins the COVID-19 pandemic. The rise in pro-inflammatory cytokines during the ‘cytokine storm’ induce indoleamine 2,3-dioxygenase (IDO), leading to an increase in kynurenine that activates the AhR, thereby heightening the initial pro-inflammatory cytokine phase and suppressing the endogenous anti-viral response. Such AhR-driven changes underpin the heightened severity and fatality associated with pre-existent high-risk medical conditions, such as type II diabetes, as well as to how racial discrimination stress contributes to the raised severity/fatality in people from the Black Asian and Minority Ethnic (BAME) communities. The AhR is pivotal in modulating mitochondrial metabolism and co-ordinating specialized, pro-resolving mediators (SPMs), the melatonergic pathways, acetyl-coenzyme A, and the cyclooxygenase (COX) 2-prostaglandin (PG) E2 pathway that underpin ‘exhaustion’ in the endogenous anti-viral cells, paralleling similar metabolic suppression in cytolytic immune cells that is evident across all cancers. 
  • 893
  • 24 Dec 2021
Topic Review
African Union Strategy on COVID-19 Vaccine
The African Union (AU) vaccination strategy seems to be very optimistic, with major challenges that might hinder the achievement of the main goal of vaccinating 60% of the population, even by 2023. Major health system reforms, as well as better resource allocation, will be crucial for countries to achieve better results.
  • 982
  • 24 Dec 2021
Topic Review
COVID-19 and Developmental Biology, Exosomes, Transcriptome
A review on COVID-19 in the context of developmental biology, exosomes, and transcriptome.
  • 625
  • 23 Dec 2021
Topic Review
Xanthohumol Is a Potent Pan-Inhibitor of Coronaviruses
Coronaviruses cause diseases in humans and livestock. The SARS-CoV-2 is infecting millions of human beings, with high morbidity and mortality worldwide. The main protease (Mpro) of coronavirus plays a pivotal role in viral replication and transcription, which, in theory, is an attractive drug target for antiviral drug development. It has been extensively discussed whether Xanthohumol is able to help COVID-19 patients. Here, researchers report that Xanthohumol, a small molecule in clinical trials from hops (Humulus lupulus), was a potent pan-inhibitor for various coronaviruses by targeting Mpro, for example, betacoronavirus SARS-CoV-2 (IC50 value of 1.53 μM), and alphacoronavirus PEDV (IC50 value of 7.51 μM). Xanthohumol inhibited Mpro activities in the enzymatical assays, while pretreatment with Xanthohumol restricted the SARS-CoV-2 and PEDV replication in Vero-E6 cells. Therefore, Xanthohumol is a potent pan-inhibitor of coronaviruses and an excellent lead compound for further drug development.
  • 919
  • 22 Dec 2021
Topic Review
Renin-Angiotensin System Dysregulation as Severe COVID-19 Factor
Since the first months of the coronavirus disease 2019 (COVID-19) pandemic, several specific physiologic traits, such as male sex and older age, or health conditions, such as overweight/obesity, arterial hypertension, metabolic syndrome, and type 2 diabetes mellitus, have been found to be highly prevalent and associated with increased risk of adverse outcomes in hospitalized patients. All these cardiovascular morbidities are widespread in the population and often coexist, thus identifying a common patient phenotype, characterized by a hyper-activation of the “classic” renin-angiotensin system (RAS) and mediated by the binding of angiotensin II (Ang II) to the type 1-receptor. At the same time, the RAS imbalance was proved to be crucial in the genesis of lung injury after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, where angiotensin-converting-enzyme-2 (ACE2) is not only the receptor for SARS-CoV-2, but its down-regulation through internalization and shedding, caused by the virus binding, leads to a further dysregulation of RAS by reducing angiotensin 1-7 (Ang 1-7) production. 
  • 831
  • 23 Dec 2021
Topic Review
Monocyte and Neutrophil Function Immunomonitoring in Critically-Ill Patients
Immune cells and mediators play a crucial role in the critical care setting but are understudied. It is clear that, for critically ill, one size does not fit all and that immune phenotyping of critically ill patients may allow the development of a more personalized approach with tailored immunotherapy for the specific patient. 
  • 930
  • 21 Dec 2021
Topic Review
Innate Immunity Promotes Programmed Death of Individual Organisms
Over-activation of innate immunity in response to bacterial or viral (including COVID-19) infections, massive trauma, or ischemia/reperfusion often causes severe illness and death. We suggest that such severe outcomes may be manifestations of an altruistic suicidal strategy protecting the entire population from the spread of pathogens and from dangerous pathologies rather than aberrant hyperstimulation of defense responses. 
  • 1.1K
  • 22 Dec 2021
Topic Review
Technologies to Assess COVID-19 Specific Antigens
In diagnosing SARS-CoV-2 infection, the most widely used test is the molecular testing. Real-time reverse transcription polymerase chain reaction (RT-PCR) is the most well-known and extensively used molecular analysis. The test relies on nucleic acid amplification and detects unique sequences of SARS-CoV-2. The other type of test, the antigen tests, can detect the presence of SARS-CoV-2 without amplifying viral components, but these tests are less sensitive than the molecular ones. Commonly, any negative antigen test is confirmed with a molecular test so that the patient can be declared negative for COVID-19. Both molecular and antigen tests would detect patients in the acute phase of infection.
  • 909
  • 21 Dec 2021
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