Age-related decline of de novo T cell responsiveness as a cause of COVID-19 severity

Age differentially impacts adaptive immune responses induced by adenoviral versus mRNA vaccines against COVID-19

Adenoviral and mRNA vaccines encoding the viral spike (S) protein have been deployed globally to contain severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Older individuals are particularly vulnerable to severe infection, probably reflecting age-related changes in the immune system, which can also compromise vaccine efficacy. It is nonetheless unclear to what extent different vaccine platforms are impacted by immunosenescence. Here, we evaluated S protein-specific immune responses elicited by vaccination with two doses of BNT162b2 or ChAdOx1-S and subsequently boosted with a single dose of BNT162b2 or mRNA-1273, comparing age-stratified participants with no evidence of previous infection with SARS-CoV-2. We found that aging profoundly compromised S protein-specific IgG titers and further limited S protein-specific CD4+ and CD8+ T cell immunity as a probable function of progressive erosion of the naive lymphocyte pool in individuals vaccinated initially with BNT162b2. Our results demonstrate that primary vaccination with ChAdOx1-S and subsequent boosting with BNT162b2 or mRNA-1273 promotes sustained immunological memory in older adults and potentially confers optimal protection against coronavirus disease 2019.

Distinct T cell responsiveness to different COVID-19 vaccines and cross-reactivity to SARS-CoV-2 variants with age and CMV status

Introduction

Accumulating evidence indicates the importance of T cell immunity in vaccination-induced protection against severe COVID-19 disease, especially against SARS-CoV-2 Variants-of-Concern (VOCs) that more readily escape from recognition by neutralizing antibodies. However, there is limited knowledge on the T cell responses across different age groups and the impact of CMV status after primary and booster vaccination with different vaccine combinations. Moreover, it remains unclear whether age has an effect on the ability of T cells to cross-react against VOCs.

Methods

Therefore, we interrogated the Spike-specific T cell responses in healthy adults of the Dutch population across different ages, whom received different vaccine types for the primary series and/or booster vaccination, using IFNɣ ELISpot. Cells were stimulated with overlapping peptide pools of the ancestral Spike protein and different VOCs.

Results

Robust Spike-specific T cell responses were detected in the vast majority of participants upon the primary vaccination series, regardless of the vaccine type (i.e. BNT162b2, mRNA-1273, ChAdOx1 nCoV-19, or Ad26.COV2.S). Clearly, in the 70+ age group, responses were overall lower and showed more variation compared to younger age groups. Only in CMV-seropositive older adults (>70y) there was a significant inverse relation of age with T cell responses. Although T cell responses increased in all age groups after booster vaccination, Spike-specific T cell frequencies remained lower in the 70+ age group. Regardless of age or CMV status, primary mRNA-1273 vaccination followed by BNT162b2 booster vaccination showed limited booster effect compared to the BNT162b2/BNT162b2 or BNT162b2/mRNA-1273 primary-booster regimen. A modest reduction in cross-reactivity to the Alpha, Delta and Omicron BA.1, but not the Beta or Gamma variant, was observed after primary vaccination.

Discussion

Together, this study shows that age, CMV status, but also the primary-booster vaccination regimen influence the height of the vaccination-induced Spike-specific T cell response, but did not impact the VOC cross-reactivity.

Effective virus-specific T-cell therapy for high-risk SARS-CoV-2 infections in hematopoietic stem cell transplant recipients: initial case studies and literature review

The COVID-19 pandemic has exacerbated mortality rates among immunocompromised patients, accentuating the need for novel, targeted therapies. Transplant recipients, with their inherent immune vulnerabilities, represent a subgroup at significantly heightened risk. Current conventional therapies often demonstrate limited effectiveness in these patients, calling for innovative treatment approaches. In immunocompromised transplant recipients, several viral infections have been successfully treated by adoptive transfer of virus-specific T-cells (VST). This paper details the successful application of SARS-CoV-2-specific memory T-cell therapy, produced by an interferon-γ cytokine capture system (CliniMACS® Prodigy device), in three stem cell transplant recipients diagnosed with COVID-19 (case 1: alpha variant, cases 2 and 3: delta variants). These patients exhibited persistent SARS-CoV-2 PCR positivity accompanied by bilateral pulmonary infiltrates and demonstrated only partial response to standard treatments. Remarkably, all three patients recovered and achieved viral clearance within 3 to 9 weeks post-VST treatment. Laboratory follow-up investigations identified an increase in SARS-CoV-2-specific T-cells in two of the cases. A robust anti-SARS-CoV-2 S (S1/S2) IgG serological response was also recorded, albeit with varying titers. The induction of memory T-cells within the CD4 + compartment was confirmed, and previously elevated interleukin-6 (IL-6) and IL-8 levels normalized post-VST therapy. The treatment was well tolerated with no observed adverse effects. While the need for specialized equipment and costs associated with VST therapy present potential challenges, the limited treatment options currently available for COVID-19 within the allogeneic stem cell transplant population, combined with the risk posed by emerging SARS-CoV-2 mutations, underscore the potential of VST therapy in future clinical practice. This therapeutic approach may be particularly beneficial for elderly patients with multiple comorbidities and weakened immune systems.

Effectiveness of BBV152 vaccine and ChAdOx1-S vaccine in preventing severe disease among vaccinated patients admitted to a designated COVID-19 hospital in India

Purpose

Coronavirus disease 2019 (COVID-19) is a highly formidable disease. Globally, multiple vaccines have been developed to prevent and manage this disease. However, the periodic mutations of severe acute respiratory syndrome coronavirus 2 variants cast doubt on the effectiveness of commonly used vaccines in mitigating severe disease in the Indian population. This study aimed to assess the effectiveness of the BBV152 vaccine and ChAdOx1-S vaccine in preventing severe forms of the disease.

Materials and Methods

This retrospective study, based on hospital records, was conducted on 204 vaccinated COVID-19 patients using a consecutive sampling approach. Data on their vaccination status, comorbidities, and high-resolution computed tomography lung reports' computed tomography severity scores were extracted from their medical records. Fisher's exact test and binomial logistic regression analysis were employed to assess the independent associations of various factors with the dependent variables.

Results

Of the 204 records, 57.9% represented males, with a mean age of 61.5±9.8 years. Both vaccines demonstrated effective protection against severe illness (90.2%), with BBV152 offering slightly better protection compared to ChAdOx1-S. Male gender, partial vaccination, comorbid conditions, and the type of vaccine were identified as independent predictors of severe lung involvement.

Conclusion

This study indicates that both vaccines were highly effective (90%) in preventing severe forms of the disease in fully vaccinated individuals. When comparing the two vaccines, BBV152 was slightly more effective than ChAdOx1-S in preventing severe COVID-19.

Assessment of lung involvement using HRCT among vaccinated and non-vaccinated elderly COVID-19 patients admitted in a designated hospital, Tamil Nadu - A retrospective study

Introduction

The COVID-19 pandemic is considered one of the most devastating situations globally, the worst affected were the senior citizens. A number of initiatives were carried out to control the COVID-19 pandemic; one such important measure is the development of COVID-19 vaccines to prevent the disease. But the continuous emergence of new SARS-COV2 variants (antigenic drift) and its demographic variation in virulence makes the vaccine's efficacy questionable. This study is intended to evaluate the association between the degree of lung involvement and the effectiveness of vaccination against the disease in cases admitted to a designated hospital in Tamil Nadu.

Materials and Methods

A hospital records-based-retrospective research was conducted among COVID-19 patients admitted from the 1st of April 2021 to the 31st of May 2021, and information was gathered regarding their vaccination status, comorbid conditions, and CT severity score (CTSS) in the HRCT lung report. A consecutive sampling technique was used to choose the study participants; about 120 participants were included in the study. The Chi-square test and Fisher's extract test were used to evaluate the hypothesis. The relationship between a dependent variable and independent factors was estimated using multiple linear regression.

Results

Among 120 participants, about 60.2% were males and 39.8% were females. Vaccination status and comorbid conditions had a significant association with severe lung involvement in COVID-19 patients.

Conclusion

Non-vaccinated patients had severe lung involvement based on the HRCT lung scan findings than the vaccinated patients. To reduce mortality, it is essential to ensure universal coverage of COVID-19 vaccination.

Persistent Cognitive Dysfunction in a Non-Hospitalized COVID-19 Long-Hauler Patient Responding to Cognitive Rehabilitation and Citicoline Treatment

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection is characterized by severe flu-like symptoms, which can progress to life-threatening systemic inflammation and multiorgan dysfunction. The nervous system is involved in over one-third of patients, and the most common neurological manifestations concern the central nervous system, such as headache, fatigue, and brain fog. The activation of innate, humoral, and cellular immune responses, resulting in a cytokine storm and endothelial and mitochondrial dysfunctions, are the main pathophysiological mechanisms of SARS-CoV-2 infection. Citicoline is an exogenous source of choline and cytidine involved in intracellular phospholipid synthesis, which improves blood flow, brain activity, and mitochondrial dysfunction. This report will present the case of a non-hospitalized, 59-year-old female. After a mild form of SARS-CoV-2 infection, the patient developed cognitive disturbances such as forgetfulness and anomia. The multidimensional neuropsychological assessment revealed an impairment in episodic memory with borderline performance in executive and visuospatial functioning. Cognitive rehabilitation and treatment with citicoline 1000 mg/daily led to a marked improvement in symptoms after six months. Early identification of the neurological sequelae of the Coronavirus Disease 2019 (COVID-19) and timely rehabilitation interventions are required in non-hospitalized long-hauler patients with COVID-19. Long-term treatment with citicoline should be considered as potentially effective in improving cognitive functioning in subjects with Post COVID-19 Neurological Syndrome.

Ageing Curtails the Diversity and Functionality of Nascent CD8+ T Cell Responses against SARS-CoV-2

Age-related changes in the immune system are thought to underlie the vulnerability of elderly individuals to emerging viral diseases, such as coronavirus disease 2019 (COVID-19). In this study, we used a fully validated in vitro approach to determine how age impacts the generation of de novo CD8⁺ T cell responses against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of COVID-19. Our data revealed a generalized deficit in the ability of elderly individuals to prime the differentiation of naïve precursors into effector CD8⁺ T cells defined by the expression of interferon (IFN)-γ and the transcription factor T-bet. As a consequence, there was an age-related decline in the diversity of newly generated CD8⁺ T cell responses targeting a range of typically immunodominant epitopes derived from SARS-CoV-2, accompanied by an overall reduction in the expression frequency of IFN-γ. These findings have potential implications for the development of new strategies to protect the elderly against COVID-19.

COVID-19: impact on Public Health and hypothesis-driven investigations on genetic susceptibility and severity

COVID-19 is a new complex multisystem disease caused by the novel coronavirus SARS-CoV-2. In slightly over 2 years, it infected nearly 500 million and killed 6 million human beings worldwide, causing an unprecedented coronavirus pandemic. Currently, the international scientific community is engaged in elucidating the molecular mechanisms of the pathophysiology of SARS-CoV-2 infection as a basis of scientific developments for the future control of COVID-19. Global exome and genome analysis efforts work to define the human genetics of protective immunity to SARS-CoV-2 infection. Here, we review the current knowledge regarding the SARS-CoV-2 infection, the implications of COVID-19 to Public Health and discuss genotype to phenotype association approaches that could be exploited through the selection of candidate genes to identify the genetic determinants of severe COVID-19.

Comorbidities and increased mortality of COVID-19 among the elderly: A systematic review

Purpose

The purpose of current review is to conduct a systematic overview of articles published between 2019 and 2021 on the relationship of comorbidities and mortality due to Coronavirus Disease 2019 (COVID-19) among the elderly population.

Methods

We conducted a systematic search on PubMed for articles published between 2019 and 2021 to identify any cohort and case-control studies that investigated the relationship of comorbidities and COVID-19 mortality among the elderly, defined as 60 years of age and above. Databases were searched independently by two authors. Disagreements were resolved by the inclusion of a third investigator. Reviews, systematic reviews, and meta-analyses were excluded from our systematic review.

Results

A total of 15 studies were selected for our systematic review. Of the included studies, 3 were case-control, 3 were prospective cohort studies and 9 were retrospective cohort studies. As for size, 10 studies were conducted on populations of <1000 participants, 3 ranging from 1001 to 10,000, and 2 on populations of >10,000 individuals. The included studies found that the presence of certain conditions, such as cardiovascular, respiratory, renal diseases, malignancies, diseases of the nervous system and diabetes are associated to increased mortality in populations that consisted of elderly patients.

Conclusion

Results of our systematic review suggest that comorbidities contribute to increased COVID-19 mortality among the elderly. The detrimental effect of comorbidities and advanced age on the immune response could lead to a more frequent occurrence of symptomatic and severe infections with COVID-19.

CD8+ T Cells in SARS-CoV-2 Induced Disease and Cancer-Clinical Perspectives

Dysregulated innate and adaptive immunity is a sign of SARS-CoV-2-induced disease and cancer. CD8+ T cells are important cells of the immune system. The cells belong to the adaptive immunity and take a front-line defense against viral infections and cancer. Extreme CD8+ T-cell activities in the lung of patients with a SARS-CoV-2-induced disease and within the tumor microenvironment (TME) will change their functionality into exhausted state and undergo apoptosis. Such diminished immunity will put cancer cases at a high-risk group for SARS-CoV-2-induced disease, rendering viral sepsis and a more severe condition which will finally cause a higher rate of mortality. Recovering responses from CD8+ T cells is a purpose of vaccination against SARS-CoV-2. The aim of this review is to discuss the CD8+ T cellular state in SARS-CoV-2-induced disease and in cancer and to present some strategies for recovering the functionality of these critical cells.

Primary immune responses are negatively impacted by persistent herpesvirus infections in older people: results from an observational study on healthy subjects and a vaccination trial on subjects aged more than 70 years old

Background

Advanced age is accompanied by a decline of immune functions, which may play a role in increased vulnerability to emerging pathogens and low efficacy of primary vaccinations in elderly people. The capacity to mount immune responses against new antigens is particularly affected in this population. However, its precise determinants are not fully understood. We aimed here at establishing the influence of persistent viral infections on the naive T-cell compartment and primary immune responsiveness in older adults.

Methods

We assessed immunological parameters, related to CD8⁺ and CD4⁺ T-cell responsiveness, according to the serological status for common latent herpesviruses in two independent cohorts: 1) healthy individuals aged 19y to 95y (n = 150) and 2) individuals above 70y old enrolled in a primo-vaccination clinical trial (n = 137).

Findings

We demonstrate a prevalent effect of age and CMV infection on CD8⁺ and CD4⁺ naive T cells, respectively. CMV seropositivity was associated with blunted CD4⁺ T-cell and antibody responses to primary vaccination.

Interpretation

These data provide insights on the changes in adaptive immunity over time and the associated decline in vaccine efficacy with ageing. This knowledge is important for the management of emerging infectious diseases in elderly populations.

"H" is not for hydroxychloroquine-"H" is for heparin: lack of efficacy of hydroxychloroquine and the role of heparin in COVID-19-preliminary data of a prospective and interventional study from Brazil

Background

COVID-19 pandemic is the major public health problem in the world actually. It’s associated with high morbidity and mortality. To date, no therapeutic measure has a curative potential. Hydroxychloroquine (HCQ) is a drug with immunomodulatory properties that has demonstrated antiviral efficacy in in vitro experiments, with conflicting results in in vivo studies.

Methods

A single-center, prospective and interventional study, that evaluates the impact on mortality of the HCQ use in 154 patients hospitalized with COVID-19 in a Brazilian public hospital. The study also aims to determine prognostic factors that predict mortality, ICU admission and endotracheal intubation in this population.

Results

154 patients diagnosed with COVID-19 confirmed by RT-PCR and hospitalized were included. There was a male predominance (87/154, 56.5%), median age 60 years and 88% (136/154) had comorbidities. Among these, 76% (117/154) were admitted to the ICU and 29.2% (45/154) experienced EOT. The OMR was 51.3% (79/154). There was no difference in mortality between patients treated with HCQ (N = 95) and non-HCQ (N = 59) (44.1% × 55.8%, p = 0.758). In univariate analysis, age ≥ 60 years (HR 3.62, p < 0.001), need for mechanical ventilation (HR 2.17, p = 0.001), ≥ 2 comorbidities (HR 1.83, p = 0.049), SAH (HR: 1.56, p = 0.054) were predictors of mortality, as well as no use of prophylactic or therapeutic heparin (HR 3.60, p = 0.02). Multivariate analysis identified admission to the ICU (HR 8.98, p = 0.002) and advanced age (HR 3.37, p < 0.01) as independent predictors of mortality, although, use of heparin (HR 0.25, p = 0.001) was independently associated with a favorable outcome.

Conclusion

This study confirmed the absence of a benefit associated with the use of HCQ in Brazilian patients hospitalized with COVID-19. However, prophylactic or therapeutic heparin was an independent predictor for reducing mortality in this population.

Altered Basal Lipid Metabolism Underlies the Functional Impairment of Naive CD8+ T Cells in Elderly Humans

Aging is associated with functional deficits in the naive T cell compartment, which compromise the generation of de novo immune responses against previously unencountered Ags. The mechanisms that underlie this phenomenon have nonetheless remained unclear. We found that naive CD8+ T cells in elderly humans were prone to apoptosis and proliferated suboptimally in response to stimulation via the TCR. These abnormalities were associated with dysregulated lipid metabolism under homeostatic conditions and enhanced levels of basal activation. Importantly, reversal of the bioenergetic anomalies with lipid-altering drugs, such as rosiglitazone, almost completely restored the Ag responsiveness of naive CD8+ T cells. Interventions that favor lipid catabolism may therefore find utility as adjunctive therapies in the elderly to promote vaccine-induced immunity against targetable cancers and emerging pathogens, such as seasonal influenza viruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Possible effects of sirolimus treatment on the long‑term efficacy of COVID‑19 vaccination in patients with β‑thalassemia: A theoretical perspective

The pandemic caused by the severe acute respiratory syndrome coronavirus (SARS‑CoV‑2), responsible for coronavirus disease 2019 (COVID‑19) has posed a major challenge for global health. In order to successfully combat SARS‑CoV‑2, the development of effective COVID‑19 vaccines is crucial. In this context, recent studies have highlighted a high COVID‑19 mortality rate in patients affected by β‑thalassemia, probably due to their co‑existent immune deficiencies. In addition to a role in the severity of SARS‑CoV‑2 infection and in the mortality rate of COVID‑19‑infected patients with thalassemia, immunosuppression is expected to deeply affect the effectivity of anti‑COVID‑19 vaccines. In the context of the interplay between thalassemia‑associated immunosuppression and the effectiveness of COVID‑19 vaccines, the employment of immunomodulatory molecules is hypothesized. For instance, short‑term treatment with mammalian target of rapamycin inhibitors (such as everolimus and sirolimus) has been found to improve responses to influenza vaccination in adults, with benefits possibly persisting for a year following treatment. Recently, sirolimus has been considered for the therapy of hemoglobinopathies (including β‑thalassemia). Sirolimus induces the expression of fetal hemoglobin (and this may contribute to the amelioration of the clinical parameters of patients with β‑thalassemia) and induces autophagy (thereby reducing the excessive levels of α‑globin). It may also finally contribute to the mobilization of erythroid cells from the bone marrow (thereby reducing anemia). In the present study, the authors present the hypothesis that sirolimus treatment, in addition to its beneficial effects on erythroid‑related parameters, may play a crucial role in sustaining the effects of COVID‑19 vaccination in patients with β‑thalassemia. This hypothesis is based on several publications demonstrating the effects of sirolimus treatment on the immune system.

Citicoline and COVID-19-Related Cognitive and Other Neurologic Complications

With growing concerns about COVID-19’s hyperinflammatory condition and its potentially damaging impact on the neurovascular system, there is a need to consider potential treatment options for managing short- and long-term effects on neurological complications, especially cognitive function. While maintaining adequate structure and function of phospholipid in brain cells, citicoline, identical to the natural metabolite phospholipid phosphatidylcholine precursor, can contribute to a variety of neurological diseases and hypothetically toward post-COVID-19 cognitive effects. In this review, we comprehensively describe in detail the potential citicoline mechanisms as adjunctive therapy and prevention of COVID-19-related cognitive decline and other neurologic complications through citicoline properties of anti-inflammation, anti-viral, neuroprotection, neurorestorative, and acetylcholine neurotransmitter synthesis, and provide a recommendation for future clinical trials.

SARS-CoV-2 infection: Understanding the immune system abnormalities to get an adequate diagnosis

COVID-19 is the current pandemic caused by the novel coronavirus, SARS-CoV-2, that emerged from China at the end of December 2019. The scientific community is making extraordinary efforts to understand the virus structure and the pathophysiology and immunological processes activated in the host, in order to identify biomarkers, diagnostic tools, treatments, and vaccines to decrease COVID-19 incidence and mortality. Various abnormalities have been noted during SARS-CoV-2 infection both in lymphoid and myeloid cells. Such abnormalities may disturb the immune system function and cause a massive inflammatory response that impairs tissue function. This review discusses the close relationship between the immune system abnormalities and the broad spectrum of clinical manifestations, including fibrosis, in the context of COVID-19 disease. Moreover, we described the current strategies for COVID-19 diagnosis, and we provide a summary of the most useful clinical laboratory parameters to identify severe COVID-19 patients.

Animal reservoirs of SARS-CoV-2: calculable COVID-19 risk for older adults from animal to human transmission

The current COVID-19 pandemic, caused by the highly contagious respiratory pathogen SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), has already claimed close to three million lives. SARS-CoV-2 is a zoonotic disease: it emerged from a bat reservoir and it can infect a number of agricultural and companion animal species. SARS-CoV-2 can cause respiratory and intestinal infections, and potentially systemic multi-organ disease, in both humans and animals. The risk for severe illness and death with COVID-19 significantly increases with age, with older adults at highest risk. To combat the pandemic and protect the most susceptible group of older adults, understanding the human-animal interface and its relevance to disease transmission is vitally important. Currently high infection numbers are being sustained via human-to-human transmission of SARS-CoV-2. Yet, identifying potential animal reservoirs and potential vectors of the disease will contribute to stronger risk assessment strategies. In this review, the current information about SARS-CoV-2 infection in animals and the potential spread of SARS-CoV-2 to humans through contact with domestic animals (including dogs, cats, ferrets, hamsters), agricultural animals (e.g., farmed minks), laboratory animals, wild animals (e.g., deer mice), and zoo animals (felines, non-human primates) are discussed with a special focus on reducing mortality in older adults.

Association between HLA genotypes and COVID-19 susceptibility, severity and progression: a comprehensive review of the literature

The COVID-19 pandemic has markedly impacted on cultural, political, and economic structures all over the world. Several aspects of its pathogenesis and related clinical consequences have not yet been elucidated. Infection rates, as well morbidity and mortality differed within countries. It is intriguing for scientists to understand how patient genetics may influence the outcome of the condition, to clarify which aspects could be related the clinical variability of SARS-CoV-2 disease. We reviewed the studies exploring the role of human leukocyte antigens (HLA) genotypes on individual responses to SARS-CoV-2 infection and/or progression, discussing also the contribution of the immunological patterns MHC-related. In March 2021, the main online databases were accessed. All the articles that investigated the possible association between the HLA genotypes and related polymorphisms with susceptibility, severity and progression of COVID-19 were considered. Although both genetic and environmental factors are certainly expected to influence the susceptibility to or protection of individuals, the HLA and related polymorphisms can influence susceptibility, progression and severity of SARS-CoV-2 infection. The crucial role played by HLA molecules in the immune response, especially through pathogen-derived peptide presentation, and the huge molecular variability of HLA alleles in the human populations could be responsible for the different rates of infection and the different patients following COVID-19 infection.

Impaired Priming of SARS-CoV-2-Specific Naive CD8+ T Cells in Older Subjects

Advanced age is associated with severe symptoms and death upon SARS-CoV-2 infection. Virus-specific CD8⁺ T-cell responses have shown to be protective toward critical COVID-19 manifestations, suggesting that suboptimal cellular immunity may contribute to the age-pattern of the disease. The induction of a CD8⁺ T-cell response against an emerging pathogen like SARS-CoV-2 relies on the activation of naive T cells. To investigate whether the primary CD8⁺ T-cell response against this virus is defective in advanced age, we used an in vitro approach to prime SARS-CoV-2-specific naive CD8⁺ T cells from healthy, unexposed donors of different age groups. Compared to younger adults, older individuals display a poor SARS-CoV-2-specific T-cell priming capacity in terms of both magnitude and quality of the response. In addition, older subjects recognize a lower number of epitopes. Our results implicate that immune aging is associated with altered primary SARS-CoV-2-specific CD8⁺ T-cell responses.

Aging in COVID-19: Vulnerability, immunity and intervention

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic was first reported in Wuhan, China in December 2019, moved across the globe at an unprecedented speed, and is having a profound and yet still unfolding health and socioeconomic impacts. SARS-CoV-2, a β-coronavirus, is a highly contagious respiratory pathogen that causes a disease that has been termed the 2019 coronavirus disease (COVID-19). Clinical experience thus far indicates that COVID-19 is highly heterogeneous, ranging from being asymptomatic and mild to severe and causing death. Host factors including age, sex, and comorbid conditions are key determinants of disease severity and progression. Aging itself is a prominent risk factor for severe disease and death from COVID-19. We hypothesize that age-related decline and dysregulation of immune function, i.e., immunosenescence and inflammaging play a major role in contributing to heightened vulnerability to severe COVID-19 outcomes in older adults. Much remains to be learned about the immune responses to SARS-CoV-2 infection. We need to begin partitioning all immunological outcome data by age to better understand disease heterogeneity and aging. Such knowledge is critical not only for understanding of COVID-19 pathogenesis but also for COVID-19 vaccine development.

Human Leukocyte Antigen Complex and Other Immunogenetic and Clinical Factors Influence Susceptibility or Protection to SARS-CoV-2 Infection and Severity of the Disease Course. The Sardinian Experience

Aim

SARS-CoV-2 infection is a world-wide public health problem. Several aspects of its pathogenesis and the related clinical consequences still need elucidation. In Italy, Sardinia has had very low numbers of infections. Taking advantage of the low genetic polymorphism in the Sardinian population, we analyzed clinical, genetic and immunogenetic factors, with particular attention to HLA class I and II molecules, to evaluate their influence on susceptibility to SARS-CoV-2 infection and the clinical outcome.

Method and Materials

We recruited 619 healthy Sardinian controls and 182 SARS-CoV-2 patients. Thirty-nine patients required hospital care and 143 were without symptoms, pauci-symptomatic or with mild disease. For all participants, we collected demographic and clinical data and analyzed the HLA allele and haplotype frequencies.

Results

Male sex and older age were more frequent in hospitalized patients, none of whom had been vaccinated during the previous seasonal flu vaccination campaignes. Compared to the group of asymptomatic or pauci-symptomatic patients, hospitalized patients also had a higher frequency of autoimmune diseases and glucose-6-phosphate-dehydrogenase (G6PDH) deficiency. None of these patients carried the beta-thalassemia trait, a relatively common finding in the Sardinian population. The extended haplotype HLA-A*02:05, B*58:01, C*07:01, DRB1*03:01 [OR 0.1 (95% CI 0-0.6), Pc = 0.015] was absent in all 182 patients, while the HLA-C*04:01 allele and the three-loci haplotype HLA-A*30:02, B*14:02, C*08:02 [OR 3.8 (95% CI 1.8-8.1), Pc = 0.025] were more frequently represented in patients than controls. In a comparison between in-patients and home care patients, the HLA-DRB1*08:01 allele was exclusively present in the hospitalized patients [OR > 2.5 (95% CI 2.7-220.6), Pc = 0.024].

Conclusion

The data emerging from our study suggest that the extended haplotype HLA-A*02:05, B*58:01, C*07:01, DRB1*03:01 has a protective effect against SARS-CoV-2 infection in the Sardinian population. Genetic factors that resulted to have a negative influence on the disease course were presence of the HLA-DRB1*08:01 allele and G6PDH deficiency, but not the beta-thalassemic trait. Absence of influenza vaccination could be a predisposing factor for more severe disease.

Human Leukocyte Antigen Complex and Other Immunogenetic and Clinical Factors Influence Susceptibility or Protection to SARS-CoV-2 Infection and Severity of the Disease Course. The Sardinian Experience

Aim

SARS-CoV-2 infection is a world-wide public health problem. Several aspects of its pathogenesis and the related clinical consequences still need elucidation. In Italy, Sardinia has had very low numbers of infections. Taking advantage of the low genetic polymorphism in the Sardinian population, we analyzed clinical, genetic and immunogenetic factors, with particular attention to HLA class I and II molecules, to evaluate their influence on susceptibility to SARS-CoV-2 infection and the clinical outcome.

Method and Materials

We recruited 619 healthy Sardinian controls and 182 SARS-CoV-2 patients. Thirty-nine patients required hospital care and 143 were without symptoms, pauci-symptomatic or with mild disease. For all participants, we collected demographic and clinical data and analyzed the HLA allele and haplotype frequencies.

Results

Male sex and older age were more frequent in hospitalized patients, none of whom had been vaccinated during the previous seasonal flu vaccination campaignes. Compared to the group of asymptomatic or pauci-symptomatic patients, hospitalized patients also had a higher frequency of autoimmune diseases and glucose-6-phosphate-dehydrogenase (G6PDH) deficiency. None of these patients carried the beta-thalassemia trait, a relatively common finding in the Sardinian population. The extended haplotype HLA-A*02:05, B*58:01, C*07:01, DRB1*03:01 [OR 0.1 (95% CI 0-0.6), Pc = 0.015] was absent in all 182 patients, while the HLA-C*04:01 allele and the three-loci haplotype HLA-A*30:02, B*14:02, C*08:02 [OR 3.8 (95% CI 1.8-8.1), Pc = 0.025] were more frequently represented in patients than controls. In a comparison between in-patients and home care patients, the HLA-DRB1*08:01 allele was exclusively present in the hospitalized patients [OR > 2.5 (95% CI 2.7-220.6), Pc = 0.024].

Conclusion

The data emerging from our study suggest that the extended haplotype HLA-A*02:05, B*58:01, C*07:01, DRB1*03:01 has a protective effect against SARS-CoV-2 infection in the Sardinian population. Genetic factors that resulted to have a negative influence on the disease course were presence of the HLA-DRB1*08:01 allele and G6PDH deficiency, but not the beta-thalassemic trait. Absence of influenza vaccination could be a predisposing factor for more severe disease.