Immunological aspects of COVID-19: What do we know?

Endothelial Dysfunction and Pregnant COVID-19 Patients with Thrombophilia: A Narrative Review

Pregnancy with SARS-CoV-2 infection can raise the risk of many complications, including severe COVID-19 and maternal-fetal adverse outcomes. Additionally, endothelial damage occurs as a result of direct SARS-CoV-2 infection, as well as immune system, cardiovascular, and thrombo-inflammatory reactions. In this narrative review, we focus on endothelial dysfunction (ED) in pregnancy, associated with obstetric complications, such as preeclampsia, fetal growth retardation, gestational diabetes, etc., and SARS-CoV-2 infection in pregnant women that can cause ED itself and overlap with other pregnancy complications. We also discuss some shared mechanisms of SARS-CoV-2 pathophysiology and ED.

The End or a New Era of Development of SARS-CoV-2 Virus: Genetic Variants Responsible for Severe COVID-19 and Clinical Efficacy of the Most Commonly Used Vaccines in Clinical Practice

Although the chief of the World Health Organization (WHO) has declared the end of the coronavirus disease 2019 (COVID-19) as a global health emergency, the disease is still a global threat. To be able to manage such pandemics in the future, it is necessary to develop proper strategies and opportunities to protect human life. The data on the SARS-CoV-2 virus must be continuously analyzed, and the possibilities of mutation and the emergence of new, more infectious variants must be anticipated, as well as the options of using different preventive and therapeutic techniques. This is because the fast development of severe acute coronavirus 2 syndrome (SARS-CoV-2) variants of concern have posed a significant problem for COVID-19 pandemic control using the presently available vaccinations. This review summarizes data on the SARS-CoV-2 variants that are responsible for severe COVID-19 and the clinical efficacy of the most commonly used vaccines in clinical practice. The consequences after the disease (long COVID or post-COVID conditions) continue to be the subject of studies and research, and affect social and economic life worldwide.

COVID-19 related liver injuries in pregnancy

While severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) quickly spread across the globe, our understanding of its pathogenic mechanisms evolved. Importantly, coronavirus disease 2019 (COVID-19) is now considered a syndromic multisystem inflammatory disease involving not only the respiratory system but also the cardiovascular, excretory, nervous, musculoskeletal, and gastrointestinal systems. Moreover, a membrane-bound form of angiotensin-converting enzyme 2, the entry receptor for SARS-CoV-2, is expressed on the surface of cholangiocytes and hepatocytes, suggesting the potential of COVID-19 to involve the liver. With the widespread distribution of SARS-CoV-2 throughout the population, infection during pregnancy is no longer a rare occurrence; however, little is known about the course of hepatic injuries and related outcomes in pregnant SARS-CoV-2-positive women. Thus, the understudied topic of COVID-related liver disease during pregnancy poses a great challenge for the consulting gynecologist and hepatologist. In this review, we aim to describe and summarize potential liver injuries in pregnant women with COVID-19.

Retroperitoneal and abdominal bleeding in anticoagulated COVID-19 hospitalized patients: Case series and brief literature review

BACKGROUND

Hospitalized and severely ill coronavirus disease 2019 (COVID-19) patients necessitate prophylactic or therapeutic anticoagulation to minimize the risk of thrombosis at different sites. Life-threatening bleeding complications include spontaneous iliopsoas hematoma, peritoneal bleeding, and extra-abdominal manifestations such as intracranial hemorrhage.

CASE SUMMARY

Bleeding in the abdominal wall results in less severe complications than seen with iliopsoas hematoma or peritoneal bleeding. In our case series of 9 patients, we present retroperitoneal and abdominal bleeding complications following anticoagulation in hospitalized COVID-19 patients with severe acute respiratory syndrome coronavirus 2 pneumonia. Contrast-enhanced computed tomography (CE-CT) is the best imaging modality for assessing hematoma secondary to anticoagulation and determines the therapeutic approach, whether interventional, surgical, or conservative management.

CONCLUSION

We present the role of CE-CT for rapid and precise localization of the bleeding site and prognostic counseling. Finally, we provide a brief review of the literature.

Perplexity as a provocation: revisiting the role of metaphor as a 'place holder' for the potential of COVID-19 antibodies

This article revisits long-standing critiques of the role of metaphor in immunological discourse. Drawing on Alfred North Whitehead's speculative philosophy of organism, I focus on the use of metaphor to explain the process by which COVID-19 vaccine research is able to generate protective antibodies, the challenge of autoimmune disease and dengue fever antibodies. I suggest that metaphors are provoked by the perplexity that arises from presupposing that distinct morphological substances are the first order of reality. I conclude that rather than seeing metaphors as typically skewing conceptions of the body, as has been previously argued, those of memory, recognition and misrecognition may be instructive of a body in transition. Indeed, a process of transition that shows degrees of creativity. When gesturing towards the processual nature of infection and immunity, metaphors invite new modes of shared thinking across the disciplinary divide.

Mucosal COVID-19 vaccines: Risks, benefits and control of the pandemic

Based on mucosal immunization to promote both mucosal and systemic immune responses, next-generation coronavirus disease 2019 (COVID-19) vaccines would be administered intranasally or orally. The goal of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines is to provide adequate immune protection and avoid severe disease and death. Mucosal vaccine candidates for COVID-19 including vector vaccines, recombinant subunit vaccines and live attenuated vaccines are under development. Furthermore, subunit protein vac-cines and virus-vectored vaccines have made substantial progress in preclinical and clinical settings, resulting in SARS-CoV-2 intranasal vaccines based on the previously successfully used nasal vaccines. Additional to their ability to trigger stable, protective immune responses at the sites of pathogenic infection, the development of ‘specific’ mucosal vaccines targeting coronavirus antigens could be an excellent option for preventing future pandemics. However, their efficacy and safety should be confirmed.

Vaccines and autoimmunity during the COVID-19 pandemic

To control the pandemic, efficient vaccines must be applied to the population, including patients with autoimmune diseases. Therefore, one can expect that coronavirus disease 2019 (COVID-19) vaccines may influence the underlying autoimmune processes in these patients. Additionally, it is essential to understand whether COVID-19 vaccines would be effective, safe, and provide long-lasting immunological protection and memory. However, the currently available and approved COVID-19 vaccines turned out to be safe, effective, and reliable in patients with autoimmune inflammatory and rheumatic diseases. Furthermore, most patients said they felt safer after getting vaccinations for COVID-19 and reported enhanced overall quality of life and psychological wellbeing. In general, the COVID-19 vaccines have been highly tolerated by autoimmune patients. Such findings might comfort patients who are reluctant to use COVID-19 vaccines and assist doctors in guiding their patients into receiving vaccinations more easily and quickly.

Immunological features of the multisystem inflammatory syndrome associated with SARS-CoV-2 in children

A particular group of children developed severe multisystem inflammation associated with current or recent SARS-CoV-2 infection or contact with a COVID-19 patient in the previous few weeks. The condition was defined as multisystem inflammatory syndrome (MIS) in children (MIS-C). As the definition of CDC and WHO is fast widely accepted, the lack of an international consensus on the definition of the syndrome cases, however, leads to some difficulties for clinicians. Additionally, MIS-C shares some immunological, pathological features with the conditions, such as cytokine storm, long COVID and/or post-COVID syndrome. The picture is further complicated by the existence of the syndrome in adults (MIS-A). Therefore, we have compared these conditions from the immunological point of view in our review based on the published case reports, studies, systematic reviews and metaanalyses. This knowledge is essential not only for immunologists. The paediatricians must be familiar with the immunological bases of the syndrome and implement it in on-time recognition and diagnosis and minimize systemic damage of this life-threatening condition at the earliest stage possible. Further investigations still need to be done to find and develop the best effective therapy and prophylactics.

In Vitro Exposure of Primary Human T Cells and Monocytes to Polyclonal Stimuli Reveals a Basal Susceptibility to Display an Impaired Cellular Immune Response and Develop Severe COVID-19

The contribution of the cellular immune response to the severity of coronavirus disease 2019 (COVID-19) is still uncertain because most evidence comes from patients receiving multiple drugs able to change immune function. Herein, we conducted a prospective cohort study and obtained blood samples from 128 unvaccinated healthy volunteers to examine the in vitro response pattern of CD4+ and CD8+ T cells and monocyte subsets to polyclonal stimuli, including anti-CD3, anti-CD28, poly I:C, severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) recombinant spike S1 protein, and lipopolysaccharide. Then, we started a six-month follow-up and registered 12 participants who got SARS-CoV-2 infection, from whom we retrospectively analyzed the basal immune response pattern of T cells and monocytes. Of the 12 participants infected, six participants developed mild COVID-19 with self-limiting symptoms such as fever, headache, and anosmia. Conversely, six other participants developed severe COVID-19 with pneumonia, respiratory distress, and hypoxia. Two severe COVID-19 cases required invasive mechanical ventilation. There were no differences between mild and severe cases for demographic, clinical, and biochemical baseline characteristics. In response to polyclonal stimuli, basal production of interleukin-2 (IL-2) and interferon (IFN-) gamma significantly decreased, and the programmed cell death protein 1 (PD-1) increased in CD4+ and CD8+ T cells from participants who posteriorly developed severe COVID-19 compared to mild cases. Likewise, CD14++CD16- classical and CD14+CD16+ non-classical monocytes lost their ability to produce IFN-alpha in response to polyclonal stimuli in participants who developed severe COVID-19 compared to mild cases. Of note, neither the total immunoglobulin G serum titers against the virus nor their neutralizing ability differed between mild and severe cases after a month of clinical recovery. In conclusion, using in vitro polyclonal stimuli, we found a basal immune response pattern associated with a predisposition to developing severe COVID-19, where high PD-1 expression and low IL-2 and IFN-gamma production in CD4+ and CD8+ T cells, and poor IFN-alpha expression in classical and non-classical monocytes are linked to disease worsening. Since antibody titers did not differ between mild and severe cases, these findings suggest cellular immunity may play a more crucial role than humoral immunity in preventing COVID-19 progression.

Observational Study of Receptor Binding Domain Spike Antibody Responses to 3 SARS-CoV-2 Vaccinations in Noninfected Subjects: Parallel Neutralizing Antibody and Cardiac Troponin I and T Observations

Background

Our goals were to demonstrate receptor binding domain spike 1 (RBD S1) protein antibody (Ab) kinetic responses to multiple vaccines over approximately 180 days, neutralizing Ab effectiveness, and high-sensitivity cardiac troponin I (hs-cTnI) and T (hs-cTnT) responses in postvaccinated, non-SARS-CoV-2–infected subjects.

Methods

Blood specimens were collected pre- and postvaccinations from seronegative subjects. RDB S1 Abs were measured by the novel Qorvo Biotechnologies Omnia platform. Neutralizing Abs and hs-cTnI and hs-cTnT were measured on the ET Healthcare Pylon 3D.

Results

Two-dose vaccines (Pfizer, Moderna) had peak RBD S1 Ab concentrations about 45 to 55 days after both doses and showed declines over the next 50 to 70 days. The Janssen vaccine showed lower RBD S1 Ab peak concentrations, continued to increase over time, and plateaued after 60 days. There was strong neutralizing Ab response post vaccinations, with only 3 specimens, shortly before and shortly after vaccination, not showing a response. Specimens showed no hs-cTnI (all < 3 ng/L) and hs-cTnT (all < 6 ng/L) increases or changes over time.

Conclusions

We demonstrate in seronegative SARS-CoV-2 subjects that Pfizer and Moderna vaccinations provide strong, neutralizing RBD S1 Ab effectiveness, based on 2 different assays after 2 doses, with the Janssen single-dose vaccine showing a lower RBD S1 Ab response over 4 to 6 months. No myocardial injury was associated with the Pfizer postvaccination. The Qorvo Biotechnologies RBD S1 Ab assay measured on the Omnia platform has potential as a point-of-care platform.

Histopathological and molecular links of COVID-19 with novel clinical manifestations for the management of coronavirus-like complications

Coronavirus disease 2019 (COVID-19) causes transmissible viral illness of the respiratory tract prompted by the SARS-CoV-2 virus. COVID-19 is one of the worst global pandemics affecting a large population worldwide and causing catastrophic loss of life. Patients having pre-existing chronic disorders are more susceptible to contracting this viral infection. This pandemic virus is known to cause notable respiratory pathology. Besides, it can also cause extra-pulmonary manifestations. Multiple extra-pulmonary tissues express the SARS-CoV-2 entry receptor, hence causing direct viral tissue damage. This insightful review gives a brief description of the impact of coronavirus on the pulmonary system, extra-pulmonary systems, histopathology, multiorgan consequences, the possible mechanisms associated with the disease, and various potential therapeutic approaches to tackle the manifestations.

The COVID-19 pandemic in the African continent

In December 2019, a new coronavirus, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and associated disease, coronavirus disease 2019 (COVID-19), was identified in China. This virus spread quickly and in March, 2020, it was declared a pandemic. Scientists predicted the worst scenario to occur in Africa since it was the least developed of the continents in terms of human development index, lagged behind others in achievement of the United Nations sustainable development goals (SDGs), has inadequate resources for provision of social services, and has many fragile states. In addition, there were relatively few research reporting findings on COVID-19 in Africa. On the contrary, the more developed countries reported higher disease incidences and mortality rates. However, for Africa, the earlier predictions and modelling into COVID-19 incidence and mortality did not fit into the reality. Therefore, the main objective of this forum is to bring together infectious diseases and public health experts to give an overview of COVID-19 in Africa and share their thoughts and opinions on why Africa behaved the way it did. Furthermore, the experts highlight what needs to be done to support Africa to consolidate the status quo and overcome the negative effects of COVID-19 so as to accelerate attainment of the SDGs.

Imaging related to underlying immunological and pathological processes in COVID-19

The introduction of coronavirus disease-2019 (COVID-19) as a global pandemic has contributed to overall morbidity and mortality. With a focus on understanding the immunology and pathophysiology of the disease, these features can be linked with the respective findings of imaging studies. Thus, the constellation between clinical presentation, histological, laboratory, immunological, and imaging results is crucial for the proper management of patients. The purpose of this article is to examine the role of imaging during the particular stages of severe acute respiratory syndrome coronavirus 2 infection – asymptomatic stage, typical and atypical COVID-19 pneumonia, acute respiratory distress syndrome, multiorgan failure, and thrombosis. The use of imaging methods to assess the severity and duration of changes is crucial in patients with COVID-19. Radiography and computed tomography are among the methods that allow accurate characterization of changes.

Continued Virus-Specific Antibody-Secreting Cell Production, Avidity Maturation and B Cell Evolution in Patients Hospitalized with COVID-19

Understanding the development and sustainability of the virus-specific protective immune response to infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) remains incomplete with respect to the appearance and disappearance of virus-specific antibody-secreting cells (ASCs) in circulation. Therefore, we performed cross-sectional and longitudinal analyses of peripheral blood mononuclear cells and plasma collected from 55 hospitalized patients up to 4 months after onset of COVID-19 symptoms. Spike (S)- and nucleocapsid (N)-specific IgM and IgG ASCs appeared within 2 weeks accompanied by flow cytometry increases in double negative plasmablasts consistent with a rapid extrafollicular B cell response. Total and virus-specific IgM and IgG ASCs peaked at 3-4 weeks and were still being produced at 3-4 months accompanied by increasing antibody avidity consistent with a slower germinal center B cell response. N-specific ASCs were produced for longer than S-specific ASCs and avidity maturation was greater for antibody to N than S. Patients with more severe disease produced more S-specific IgM and IgG ASCs than those with mild disease and had higher levels of N- and S-specific antibody. Women had more B cells in circulation than men and produced more S-specific IgA and IgG and N-specific IgG ASCs. Flow cytometry analysis of B cell phenotypes showed an increase in circulating B cells at 4-6 weeks with decreased percentages of switched and unswitched memory B cells. These data indicate ongoing antigen-specific stimulation, maturation, and production of ASCs for several months after onset of symptoms in patients hospitalized with COVID-19.

Cellular, Antibody and Cytokine Pathways in Children with Acute SARS-CoV-2 Infection and MIS-C-Can We Match the Puzzle?

The newly identified strain of the Coronaviridae family called severe acute respiratory syndrome (SARS-CoV-2) recently became the most significant health threat for adults and children. Some main predictors of severe clinical course in patients with SARS-CoV-2 infection are age and concomitant health conditions. Therefore, the proper evaluation of SARS-CoV-2-specific immunity is urgently required to understand and predict the spectrum of possible clinical phenotypes and recommend vaccination options and regimens in children. Furthermore, it is critical to characterize the nature of SARS-CoV-2-specific immune responses in children following asymptomatic infection and COVID-19 and other related conditions such as multisystem inflammatory syndrome (MIS-C), para-infectious and late postinfectious consequences. Recent studies involving children revealed a variety of cytokines, T cells and antibody responses in the pathogenesis of the disease. Moreover, different clinical scenarios in children were observed-asymptomatic seroprevalence, acute SARS-CoV-2 infection, and rarely severe COVID-19 with typical cytokine storm, MIS-C, long COVID-19, etc. Therefore, to gain a better clinical view, adequate diagnostic criteria and treatment algorithms, it is essential to create a realistic picture of the immunological puzzle of SARS-CoV-2 infection in different age groups. Finally, it was demonstrated that children may exert a potent and prolonged adaptive anti-SARS-CoV-2 immune response, with significant cross-reactions against other human Corona Viruses, that might contribute to disease sparing effect in this age range. However, the immunopathology of the virus has to be elucidated first.

Interferon-gamma release assays outcomes in healthy subjects following BNT162b2 mRNA COVID-19 vaccination

The pathogenesis of COVID-19 involves both humoral and cellular immunological responses, with cell-mediated immunity being discussed as the primary and most effective immune response to viral infection. It is supposed that COVID-19 vaccines also elicited effective cell immune response, and specifically IFNγ secreted by SARS-CoV-2-specific T-helper 1 and Tcytotoxic cells. Using an interferon-gamma release assay (IGRA) test, we aimed to monitor cellular post-vaccination immunity in healthy subjects vaccinated with BNT162b2 mRNA COVID-19 vaccine (Comirnaty). We tested 37 healthcare workers (mean age 54.3 years, range 28–72, 22 females, 15 males) following COVID-19 mRNA COVID-19 vaccine and 15 healthy unvaccinated native persons as control subjects using QuantiFERON SARS-CoV-2 RUO test, performed approximately 1 month after vaccination. We also measured virus-neutralizing antibodies. Thirty-one out of 37 tested subjects had significantly raised levels of SARS-CoV-2 specific IFNγ against SARS-CoV-2 Ag1 and Ag2 1 month following COVID-19 vaccination. In addition, we found a significant difference between the IFNγ levels in fully vaccinated subjects and the control group (p < 0.01).We also found a substantial correlation (r = 0.9; p < 0.01) between virus-neutralizing antibodies titers and IFNγ concentrations released by T cells. We believe that IGRA tests are an excellent tool to assess the development of a post-vaccination immune response when immunized against SARS-CoV-2. However, IGRA-based tests should be performed within a few weeks following vaccination. Therefore, we can speculate that the application of these tests to assess long-term immune response is debatable.

Acute Cerebellitis and Myeloradiculitis Associated With SARS-CoV-2 Infection in Common Variable Immunodeficiency—A Case Report

The role of the adaptive immune system in mediating COVID-19 is largely unknown. Therefore, it is difficult to predict the clinical course in patients with common variable immunodeficiency (CVID), a disease characterized by dysfunctional lymphocytes and impaired antibody production. We report a case of SARS-CoV-2 infection presenting as isolated neurological symptoms in a patient with CVID. The patient subsequently improved following steroids, intravenous immunoglobulin, and convalescent plasma (CP). The latter has been shown to be safe and efficacious in treating COVID-19 in patients with primary immunodeficiency. Recent data suggest that the mechanism of CNS injury in COVID-19 may be due to immunological dysregulation rather than direct viral-mediated injury. This case exemplifies the complex interaction between the brain, the immune system, and the SARS-CoV-2 virus.

Liver dysfunction as a cytokine storm manifestation and prognostic factor for severe COVID-19

Liver damage in severe acute respiratory coronavirus 2 infection occurs in patients with or without preexisting liver disorders, posing a significant complication and mortality risk. During coronavirus disease 2019 (COVID-19), abnormal liver function is typically observed. However, liver injury may occur because of the treatment as well. Ischemia, cytokine storm, and hypoxia were identified as the three major factors contributing to liver damage during COVID-19. Indeed, raised liver enzymes during hospitalizations may be attributed to medications used, as well as sepsis and shock. As a result, the proportion of hospitalized patients afflicted with COVID-19 and pathological liver biomarkers varies from 14% to 53%. Aminotransferases and bilirubin are found most often elevated. Usually, increased gamma-glutamyltransferase, alkaline phosphatase, and decreased serum albumin levels are demonstrated. Additionally, although there is no specific treatment for COVID-19, many of the drugs used to treat the infection are hepatotoxic. In this mini-review, we focus on how liver dysfunction can be one of the features associated with the COVID-19 cytokine storm. Furthermore, data show that liver injury can be an independent predictor of severe COVID-19, the need for hospitalization, and death.

Kinetics of SARS-CoV-2 Specific and Neutralizing Antibodies over Seven Months after Symptom Onset in COVID-19 Patients

To assess the persistence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies produced by natural infection and describe the serological characteristics over 7 months after symptom onset among coronavirus disease 2019 (COVID-19) patients by age and severity group, we followed up COVID-19 convalescent patients confirmed from 1 January to 20 March 2020 in Jiangsu, China and collected serum samples for testing IgM/IgG and neutralizing antibodies against SARS-CoV-2 between 26 August and 28 October 2020. In total, 284 recovered participants with COVID-19 were enrolled in our study. Patients had a mean age of 46.72 years (standard deviation [SD], 17.09), and 138 (48.59%) were male. The median follow-up time after symptom onset was 225.5 (interquartile range [IQR], 219 to 232) days. During the follow-up period (162 to 282 days after symptom onset), the seropositive rate of IgM fluctuated around 25.70% (95% confidence interval [CI], 20.72% to 31.20%) and that of IgG fluctuated around 79.93% (95% CI, 74.79% to 84.43%). Of the 284 patients, 64 participants were tested when discharged from hospital. Compared with that at the acute phase, the IgM/IgG antibody levels and IgM seropositivity have decreased; however, the seropositivity of IgG was not significantly lower at this follow-up (78.13% versus 82.81%). Fifty percent inhibitory dilution (ID₅₀) titers of neutralizing antibody for samples when discharged from hospital (geometric mean titer [GMT], 82; 95% CI, 56 to 121) were significantly higher than those at 6 to 7 months after discharge (GMT, 47; 95% CI, 35 to 63) (P < 0.001). After 7 months from symptom onset, the convalescent COVID-19 patients continued to have high IgG seropositive; however, many plasma samples decreased neutralizing activity.

IMPORTANCE The long-term characteristics of anti-SARS-CoV-2 antibodies among COVID-19 patients remain largely unclear. Tracking the longevity of these antibodies can provide a forward-looking reference for monitoring COVID-19. We conducted a comprehensive assessment combining the kinetics of specific and neutralizing antibodies over 7 months with age and disease severity and revealed influencing factors of the protection period of convalescent patients. By observing the long-term antibody levels against SARS-CoV-2 and comparing antibody levels at two time points after symptom onset, we found that the convalescent COVID-19 patients continued to have a high IgG seropositive rate; however, their plasma samples decreased neutralizing activity. These findings provide evidence supporting that the neutralizing activity of SARS-CoV-2-infected persons should be monitored and the administration of vaccine may be needed.

Liver Involvement in Children with COVID-19 and Multisystem Inflammatory Syndrome: A Single-Center Bulgarian Observational Study

SARS-CoV-2 infection may precede and cause various autoimmune and inflammatory diseases, including multisystem inflammatory syndrome in children (MIS-C). Therefore, we aimed to observe the clinical presentation and laboratory, instrumental and other constellations in children with MIS-C, including liver involvement. We present the outcomes from a single-center prospective observational study in which 89 children was included (60 with proven COVID-19, 10 symptomatic with confirmed COVID-19 contact and 19 diagnosed with MIS-C). Laboratory, instrumental, immunological, and clinical investigations were performed. Only 12% (n = 4) from the COVID-19 group (except the ICU cases), we found elevated AST and/or ALT (up to 100). All of the children with elevated transaminase were overweight or obese, presenting along with moderate COVID-19 pneumonia. The majority of children with MIS-C showed typical laboratory constellations with higher levels of IL-6 (120.36 ± 35.56 ng/mL). About half of the children in the MIS-C group (52%, n = 11) showed elevated transaminases. Eleven children (57.9%) presented with abdominal pain, eight (42.1%) with ascites, two (10.5%) with hepatosplenomegaly, and four (21.1%) with symptoms such as diarrhea. Mesenteric lymphadenitis was observed more often in patients with elevated LDH (327.83 ± 159.39, p = 0.077). Ascites was associated with lymphopenia (0.86 ± 0.80, p = 0.029) and elevated LDH. Hepato-splenomegaly was also more frequent in children with lymphopenia (0.5 ± 0.14, p = 0.039), higher troponin (402.00 ± 101.23, p = 0.004) and low ESR. Diarrhea was more frequent in patients with lower CRP (9.00 ± 3.44 vs. 22.25 ± 2.58, p = 0.04), and higher AST and ALT (469.00 ± 349.59 vs. and 286.67 ± 174.91, respectively, p = 0.010), and D-dimer (4516.66 ± 715.83, p = 0.001). Our data suggest that the liver can also be involved in MIS-C, presenting with typical laboratory and instrumental outcomes.

An Overview of COVID-19 and the Potential Plant Harboured Secondary Metabolites against SARS-CoV-2: A Review

The SARS-CoV-2 virus causes COVID-19, a pandemic disease, and it is called the novel coronavirus. It belongs to the Coronaviridae family and has been plagued the world since the end of 2019. Viral infection to the lungs causes fluid filling and breathing difficulties, which leads to pneumonia. Pneumonia progresses to ARDS (Acute Respiratory Distress Syndrome), in which fluid fills the air sac and seeps from the pulmonary veins. In the current scenario, several vaccines have been used to control the pandemic worldwide. Even though vaccines are available and their effectiveness is short, it may be helpful to curb the pandemic, but long-term protection is inevitable when we look for other options. Plants have diversified components such as primary and secondary metabolites. These molecules show several activities such as anti-microbial, anti-cancer, anti-helminthic. In addition, these molecules have good binding ability to the SARS-CoV-2 virus proteins such as RdRp (RNA-dependent RNA polymerase), Mpro (Main Protease), etc. Therefore, these herbal molecules could probably be used to control the COVID-19. However, pre-requisite tests, such as cytotoxicity, in vivo, and human experimental studies, are required before plant molecules can be used as potent drugs. Plant metabolites such as alkaloids, isoquinoline ß-carboline, and quinoline alkaloids such as skimmianine, quinine, cinchonine, and dictamine are present in plants and used in a traditional medicinal system.

Vaccine responses in ageing and chronic viral infection

Over the last few decades, changing population demographics have shown that there are a growing number of individuals living past the age of 60. With this expanding older population comes an increase in individuals that are more susceptible to chronic illness and disease. An important part of maintaining health in this population is through prophylactic vaccination, however, there is growing evidence that vaccines may be less effective in the elderly. Furthermore, with the success of anti-viral therapies, chronic infections such as HIV are becoming increasingly prevalent in older populations and present a relatively unstudied population with respect to the efficacy of vaccination. Here we will examine the evidence for age-associated reduction in antibody and cellular responsiveness to a variety of common vaccines and investigate the underlying causes attributed to this phenomenon, such as inflammation and senescence. We will also discuss the impact of chronic viral infections on immune responses in both young and elderly patients, particularly those living with HIV, and how this affects vaccinations in these populations.

INFECTION-ACQUIRED VERSUS VACCINE-INDUCED IMMUNITY AGAINST COVID-19

The course of COVID-19 depends on a dynamic interplay between SARS-CoV-2 and the host's immune system. Although it is an emerging global health issue, little is known about the specificity, safety, and duration of the immunity elicited by the virus. This hypothesis article explores the benefits of infection-acquired and vaccine-induced immunity against COVID-19, suggesting that the latter outweighs the former. Comparative studies are proposed to explain and reveal all aspects of the immune responses. Although vaccine development relies on studies of naturally acquired immune responses, there are still no comparative analyses of the natural and vaccine immunity against SARS-CoV-2. Moreover, there are scarce reports on the characteristics of both types of responses. The scientific facts about the virulence of SARS-CoV-2 affecting the immune system are of great importance for proposed comparative analyses. Various immunological methods can be employed to elucidate infection-acquired and vaccine-induced immunity against SARS-CoV-2. The safe vaccination of subjects with and without COVID-19 history may disrupt the virus spreading and end the pandemic.