Search Results (375)

Despite targeting mainly the respiratory tract, SARS-CoV-2 disrupts T cell homeostasis in ways that may explain both acute lethality and long-term immunological consequences. In this study, we aimed to evaluate the T-cell-mediated chain of immunity and formation of TCR via TREC assessment in COVID-19 and long COVID (LC). For this study, we collected 231 blood samples taken from patients with acute COVID-19 (n = 71), convalescents (n = 51), people diagnosed with LC (n = 63), and healthy volunteers (n = 46). With flow cytometry, we assessed levels of CD4+ and CD8+ minor T cell subpopulations (i.e., naïve, central and effector memory cells (CM and EM), Th1, Th2, Th17, Tfh, Tc1, Tc2, Tc17, Tc17.1, and subpopulations of effector cells (pE1, pE2, effector cells)). Additionally, we measured TREC levels. We found distinct changes in immune cell distribution—whilst distribution of major subpopulations of T cells was similar between cohorts, we noted that COVID-19 was associated with a decrease in naïve Th and CTLs, an increase in Th2/Tc2 lymphocyte polarization, an increase in CM cells, and a decrease in effector memory cells 1,3, and TEMRA cells. LC was associated with naïve CTL increase, polarization towards Th2 population, and a decrease in Tc1, Tc2, Em2, 3, 4 cells. We also noted TREC correlating with naïve cells subpopulations. Our findings suggest ongoing immune dysregulation, possibly driven by persistent antigen exposure or tissue migration of effector cells. The positive correlation between TREC levels and naïve T cells in LC patients points to residual thymic activity. The observed Th2/Th17 bias supports the hypothesis that LC involves autoimmune mechanisms, potentially driven by molecular mimicry or loss of immune tolerance. Full article

Monitoring Peripheral Oxygen Saturation (SpO₂) is an important vital sign both in Intensive Care Units (ICUs), during surgery and convalescence, and as part of remote medical consultations after of the COVID-19 pandemic. This has made the development of new SpO₂-measurement tools an area of active research and opportunity. In this paper, we present a new Deep Learning (DL) combined strategy to estimate SpO₂ without contact, using pre-magnified facial videos to reveal subtle color changes related to blood flow and with no calibration per subject required. We applied the Eulerian Video Magnification technique using the Hermite Transform (EVM-HT) as a feature detector to feed a Three-Dimensional Convolutional Neural Network (3D-CNN). Additionally, parameters and hyperparameter Bayesian optimization and an ensemble technique over the dataset magnified were applied. We tested the method on 18 healthy subjects, where facial videos of the subjects, including the automatic detection of the reference from a contact pulse oximeter device, were acquired. As performance metrics for the SpO₂-estimation proposal, we calculated the Mean Absolute Error (MAE), Root Mean Squared Error (RMSE), and other parameters from the Bland–Altman (BA) analysis with respect to the reference. Therefore, a significant improvement was observed by adding the ensemble technique with respect to the only optimization, obtaining 14.32% in RMSE (reduction from 0.6204 to 0.5315) and 13.23% in MAE (reduction from 0.4323 to 0.3751). On the other hand, regarding Bland–Altman analysis, the upper and lower limits of agreement for the Mean of Differences (MOD) between the estimation and the ground truth were 1.04 and −1.05, with an MOD (bias) of −0.00175; therefore, MOD $\pm 1.96\sigma$ = −0.00175 ± 1.04. Thus, by leveraging Bayesian optimization for hyperparameter tuning and integrating a Bagging Ensemble, we achieved a significant reduction in the training error (bias), achieving a better generalization over the test set, and reducing the variance in comparison with the baseline model for SpO₂ estimation. Full article

Our study demonstrates that IVIG lots manufactured in 2023–2024 contain neutralizing antibodies against circulating Omicron variants, including KP.3 and XEC. These variants are resistant to all convalescent plasma and IVIG preparations produced prior to 2023. Therefore, recent IVIG lots may provide some protection against COVID-19 caused by circulating SARS-CoV-2 variants. Full article

Background/Objectives: Long COVID is a condition that was initially recognized by social support groups, and later by the scientific and medical communities. It affects COVID-19 survivors at various levels of severity, including young people, children and non-hospitalized people. Although the exact definition is unclear, the most common symptoms are fatigue and shortness of breath, which persist for months. Other symptoms include cognitive impairment, pain, palpitations, and gastrointestinal and heart problems. This study evaluated the reliability and validity of a questionnaire designed to examine the development and effects of long COVID. Methods: A questionnaire, composed of three sections, with a total of 24 items, was administered to subjects who had recovered from the COVID-19 disease in Italy. Data were collected from February to April 2025, and a statistical analysis was performed using R^® statistical software for Windows, version 4.3.3. Cronbach’s alpha was tested to check internal consistency. The questionnaire was completed voluntarily and anonymously by 250 individuals who had recovered from the SARS-CoV-2 infection. The questionnaire was self-administered and had open and structured questions. Results: The highest value of Cronbach’s alpha was found on 18 items (alpha = 0.97), which means that the questionnaire has satisfactory internal validity. Conclusions: This study highlights and confirms the continuity of symptoms manifested during the acute phase of the SARS-CoV-2 infection in the post-COVID-19 phase and the significant impact of these symptoms on daily life activities. Given its excellent reliability properties and high internal consistency, the instrument is recommended for future longitudinal studies and with large cohorts in order to carry out valid and replicable measurements of COVID-19 symptomatology. Full article

Background: SARS-CoV-2 was the causing agent of the COVID-19 pandemic, which resulted in millions of deaths worldwide and massive economic losses. Although there are already several vaccines licensed, as novel variants develop, understanding the immune response induced by vaccination and natural infection is key for the development of future vaccines. Methods: In this study, we have used flow cytometry and next-generation sequencing to assess the longitudinal CD8⁺ T-cell response against natural infection and vaccination in convalescent and vaccinated individuals, from early activation to immune memory establishment. Moreover, we have characterized the T-cell receptor clonality and diversity at different stages post-infection and post-vaccination. Results: We have found no significant differences in CD8⁺ T-cell activation during the first three weeks post-infection compared to the first three weeks after first vaccination. Conversely, natural infection resulted in sustained high levels of T-cell activation at four weeks post-infection, a point in which we observed a decline in T-cell activation post-vaccination despite boosting with a second vaccination shot. Moreover, additional vaccination did not result in enhanced T-cell activation. Of note, we have observed variations in the memory subset structure at every stage of disease and vaccination. Overall, both infection and immunization induced a highly diverse T-cell receptor repertoire, which was observed both between study groups and between patients inside a given group. Conclusions: These data contribute to expand our knowledge about the immune response to SARS-CoV-2 infection and vaccination and call for additional strategies to enhance T-cell responses by booster immunization. Full article

Background: Since the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in December 2019, long COVID (LC) has become a significant global health burden. While knowledge about LC is accumulating, studies on its prevention are still lacking. Methods: We conducted a systematic review following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to investigate prevention options for LC. We identified fifteen articles on vaccines, seven on antivirals, and six on other interventions after searching for articles in the PubMed/MEDLINE database using the MeSH terms. Results: Most vaccine-related studies demonstrated a protective effect of COVID-19 vaccines against developing LC. Our review found an equivocal effect of antivirals, while metformin had a protective effect in outpatients and corticosteroids were protective in hospitalized patients against LC. Conversely, COVID-19 convalescent plasma and multiple micronutrient supplement did not confer any protection against LC. Conclusions: COVID-19 vaccination is vital as it not only prevents COVID-19 but also reduces the severity of illness and may help prevent LC. Further studies are warranted to shed light on preventive strategies for long COVID. Full article

Background: Despite the multiple waves of the COVID-19 pandemic, follow-up strategies for recovered patients remain inconclusive. This study aimed to evaluate chest computed tomography (CT) and pulmonary function test (PFT) abnormalities in convalescents six months after COVID-19 and to compare these findings with those from a representative population cohort. The goal was to support more individualized pulmonary management of post-COVID-19 sequelae. Methods: This study population consisted of 2 groups: I—232 post-COVID-19 patients and II—543 patients from a population cohort. Chest CT was performed during the acute phase of COVID-19 and six months after. The PFTs were conducted six months after COVID-19. Results: There were no significant differences in FEV1, FVC, TLC, and DLCO in the two study groups. A singular GGO in 24 patients (20%), a crazy paving pattern in 1 patient (0.8%), thickening of interlobular septa in 4 patients (3.5%), consolidations in 4 patients (3.5%), traction bronchiectasis in 6 patients (5%), fibrosis in 6 patients (5%), and singular nodular densities in 68 patients (58%) were observed in chest CT 6 months after COVID-19. Most radiological abnormalities were clinically insignificant and did not require further diagnostic evaluation. No significant differences in chest CT and PFT six months after infection were observed between patients differing in the severity of inflammation during the acute disease or SARS-CoV-2 variant. Conclusions: The majority of chest CT abnormalities resolved within six months of recovery, regardless of SARS-CoV-2 variant or initial disease severity. Pulmonary function tests should be prioritized in post-COVID-19 follow-up, as PFT results in convalescents were comparable to those observed in the general population. Full article

Certain strains of Influenza A virus (IAV), a primary cause of influenza, can lead to pneumonia. Patients recovering from influenza pneumonia may experience physical discomfort akin to post-acute sequelae of COVID-19 (PASC). Despite extensive clinical research on viral pneumonia during convalescence, animal model studies are scarce, highlighting the need for a reliable model for pharmaceutical research. In this study, BALB/c mice were divided into three groups: NC (control), MC (infected with IAV), and Model (treated with oseltamivir post-infection for five days). A fatigue model was then induced in the Model group through diet restriction and weight-bearing swimming. The results showed the MC group had a 75% survival rate, while the NC and Model groups had 100%. Both the MC and Model groups experienced rapid weight loss followed by gradual recovery, differing significantly from the NC group. From dpi (days post-inoculation) 6 to dpi9, the MC group lost more weight than the NC group. The MC group had the highest pulmonary index, but there was no significant difference in IAV Nucleoprotein (NP) expression across groups. The Model group had higher IL-10 levels than the NC and MC groups, while the MC group had the highest TNF-α expression. Hematoxylin and eosin (H&E) staining revealed pathological changes in the MC and Model groups, with severe damage and pulmonary fibrosis in the MC group. Oxidative stress markers showed the MC group had the highest lactate dehydrogenase (LDH) and malondialdehyde (MDA) levels and lowest superoxide dismutase (SOD) activity. Electron microscopy indicated mitochondrial damage in both the MC and Model groups. The Model group had the lowest splenic and thymic indices, with histological findings showing larger splenic nodules in the MC group and poor thymocyte density and atrophy in the Model group. The successful creation of this mouse model of influenza pneumonia convalescence phase fatigue, exhibiting fatigue syndrome with various symptoms, holds significance for PASC and other viral pneumonia convalescence phase animal model research. Full article

Background: COVID-19, caused by SARS-CoV-2, poses a significant threat to human health. Vaccines designed for T-cell epitopes play an important role in eliminating the virus. However, T cell epitope screening often requires the use of a large number of peripheral blood mononuclear cells (PBMCs) from infected or convalescent patients, and if MHC humanized mice can be used for epitope screening, they will not have to wait for enough PBMCs to be available to screen for epitopes, thus buying time for epitope confirmation and vaccine design. Methods: In this study, we used SARS-CoV-2 BA.5 to infect HLA-A11/DR1, C57BL/6, hACE2 mice, and detected body weight changes, viral load, and pathological changes after infection. Fourteen days after the HLA-A11/DR1 and C57BL/6 mice were immunized against inactivated viruses, IgG antibodies were detected in mouse serum using ELISA, and IFN-γ produced by peptide stimulation of splenocytes was detected by ELISpot. Results: There is no obvious pathogenic phenotype of SARS-CoV-2 infection in HLA-A11/DR1 mice. Specific IgG antibodies were detected in serum after immunization of inactivated virus in both HLA-A11/DR1 and C57BL/6 mice, but specific IFN-γ was detected in splenocytes of HLA-A11/DR1 mice. Conclusions: Although HLA-A11/DR1 mice are unable to replicate the virus effectively in vivo, they are able to generate cellular immune responses after immunization inactivated viruses. Therefore, it can be used as a tool to substitute for human PBMCs in epitope screening, thus shortening the timeliness of T cell epitope screening and obtaining the immunogenicity information of new epitopes in a timely manner. Full article

The emergence of COVID-19 necessitated the rapid development of vaccines. While highly effective at reducing severe disease and death, breakthrough infections remain a problem as the virus continues to mutate. To help address this issue, we show the utility of a multiplex immunoassay in measuring multiple aspects of the antibody response generated by SARS-CoV-2 vaccines. We use a multiplex immunoassay platform to measure spike-specific IgG concentration, avidity, and receptor-binding inhibition. In addition, we correlate results from an ACE-2 receptor-binding inhibition assay with corresponding data from a SARS-CoV-2 microneutralization assay to establish this inhibitory assay as a potential predictor of virus neutralization. We studied these antibody responses in SARS-CoV-2-naïve and -convalescent vaccinees. Our results showed increased IgG concentrations, avidity, and inhibition following vaccination in both groups. We were also able to differentiate the immune response between the two groups using the multiplex immunoassay platform to look at antibody diversity. The receptor-binding inhibition assay has strong correlations with a cell-based pseudovirus neutralization assay as well as with WT SARS-CoV-2 Washington and Delta variant PRNT₅₀ assays. This suggests that the inhibition assay may be able to simultaneously predict virus neutralization of different SARS-CoV-2 variants. Overall, we show that the developed custom multiplex immunoassay with several experimental variations is a powerful tool in assessing multiple aspects of the SARS-CoV-2 antibody response in vaccinated individuals. Full article

Background/Objectives: Mortality from COVID-19 in intensive care units (ICUs) was not clearly reported in many regions during the first wave. We aimed to assess the characteristics and outcomes of ICU patients with COVID-19 in Saudi Arabia. Methods: This was a secondary data analysis of the Convalescent Plasma Trial. All patients who were recruited from King Fahad Hospital of the University (KFHU) in the Eastern Region of Saudi Arabia between 13 March 2020 and 13 September 2020 were included. Characteristics and outcomes, differences in characteristics and outcomes between Saudi and non-Saudi populations, and predictors of mortality were assessed. Results: The KFHU recruited 185 ICU patients with COVID-19. Of those, 90 (48.6%) were Saudi, and 95 (51.4%) were non-Saudi. The overall mean age was 56.7 years, and 71.9% were males. Compared with Saudis, non-Saudis were younger, with a mean age of 54.4 years, were more likely to be males (81.1%), and had a higher median respiratory rate (28.0 breaths/min vs. 24.0), a lower percentage of blood-oxygen saturation (86.0% vs. 91.0%), and higher median levels of ferritin per µg/L (820 vs. 550). The overall mortality rate was 33.0% (n = 61). The mortality rate in non-Saudis (42.1%) was higher than that in Saudis (23.3%). The variables associated with increased mortality included non-Saudi status (odds ratio [OR] 2.66; 95% CI: 1.05, 6.72), ferritin (OR 1.01; 95% CI: 1.00, 1.02), and intubation (OR 8.55; 95% CI: 2.92, 24.97). Conclusions: Since the mortality rate in non-Saudis was greater than that in Saudis, more efforts should be made to improve social determinants of health across non-Saudis in our region. Full article

Background: The aim of this study was to evaluate whether increased body mass index (BMI) and biochemical and lifestyle parameters linked to obesity and smoke exposure disrupt immune responses of children and adolescents following vaccination with the mRNA BNT162b2 vaccine. Methods: A prospective, single-center, cohort study was conducted. Participants were assigned to receive two doses of the mRNA vaccine. Anti-SARS-CoV-2 IgG and neutralizing antibodies (AB) were measured before vaccination (T0) and 14 days after the second dose (T1). BMI and biochemical parameters were evaluated at T0. A questionnaire on lifestyle characteristics was filled in. Results: IgG optical density (OD) ratio at T1 was lower in the overweight–obese group regardless of COVID-19 disease positive history [p = 0.028 for the seronegative group, p = 0.032 for the seropositive group]. Neutralizing AB were lower in overweight–obese participants in the seronegative group at T1 [p = 0.008]. HDL, fasting glucose/insulin ratio (FGIR), C-reactive protein (CRP), HBA1c, uric acid, and smoke exposure were significantly correlated with BMI [p = 0.006, p < 0.001, p < 0.001, p = 0.006, p = 0.009, p < 0.001, respectively]. The main biochemical parameters that were inversely correlated with IgG and neutralizing AB titers at T1 were uric acid [p = 0.018, p = 0.002], FGIR [p = 0.001, p = 0.008] and HBA1C [p = 0.027, p = 0.038], while smoke exposure negatively affected the humoral immune responses at T0 in the convalescent group [p = 0.004, p = 0.005]. Conclusions: Current data suggests that uric acid, insulin resistance (IR), and smoke exposure could adversely affect the immune responses in overweight–obese vaccinated children, highlighting the need for actions to enhance the protection of this particular subgroup. Full article

Blood products, including apheresis platelets and plasma, are essential for medical use but pose risks of bacterial contamination and viral transmission. Platelets are prone to bacterial growth due to their storage conditions, while plasma requires extensive screening. This study explores rapid irradiation as an innovative pathogen reduction method. A clinical linear accelerator was configured to deliver ultra-high dose rate (6 kGy/min) irradiation to platelet and plasma components. Platelets spiked with Escherichia coli (E. coli; 10⁵ colony-forming units) were irradiated at 0.1–20 kGy, followed by bacterial growth and platelet count analysis. COVID-19 convalescent plasma (CCP) was irradiated at 25 kGy, and receptor-binding domain (RBD)-specific immunoglobulins (Ig) were assessed. Irradiation at 1 kGy reduced E. coli growth by 2.7-log without significant platelet loss, while 5 kGy achieved complete suppression. The estimated 6-log bacterial reduction dose (2.3 kGy) led to a 31% platelet count drop. Administering a 25 kGy virus-sterilizing dose to CCP resulted in a 9.2% decrease in RBD-specific IgG binding. This study demonstrates the proof-of-concept for rapid blood sterilization using a clinical linear accelerator. The method maintains platelet counts and CCP antibody binding at sterilizing doses, highlighting its potential as a point-of-care blood product sterilization solution. Full article

Post-acute sequelae of SARS-CoV-2 infection (PASC), commonly known as “Long COVID”, represents a significant clinical challenge characterized by persistent symptoms following acute COVID-19 infection. We conducted a comprehensive retrospective cohort study to identify serum autoantibody biomarkers associated with PASC. Initial screening using a protein bead array comprising approximately 20,000 human proteins identified several candidate PASC-associated autoantibodies. Subsequent validation by enzyme-linked immunosorbent assay (ELISA) in an expanded cohort—consisting of PASC patients, non-PASC COVID-19 convalescents, and pre-pandemic healthy controls—revealed two promising biomarkers: autoantibodies targeting PITX2 and FBXO2. PITX2 autoantibodies demonstrated high accuracy in distinguishing PASC patients from both non-PASC convalescents (area under the curve [AUC] = 0.891) and healthy controls (AUC = 0.866), while FBXO2 autoantibodies showed moderate accuracy (AUC = 0.762 and 0.786, respectively). Notably, the levels of these autoantibodies were associated with several PASC symptoms, including fever, dyspnea, palpitations, loss of appetite, and brain fog. The identification of PITX2 and FBXO2 autoantibodies as biomarkers not only enhances our understanding of PASC pathophysiology but also provides promising candidates for further investigation. Full article

Pulmonary fibrosis (PF) emerges as a significant pulmonary sequelae in the convalescent phase of coronavirus disease 2019 (COVID-19), with current strategies neither specifically preventive nor therapeutic. Geum japonicum var. chinense (GJC) is used as a traditional Chinese medicine to effectively treat various respiratory conditions. However, the protective effects of GJC against PF remains unclear. In the present study, the anti-PF effect of GJC aqueous extract was studied using a PF mouse model induced by bleomycin (BLM). To characterize the metabolite changes related to PF and reveal therapeutic targets for GJC aqueous extract, we performed metabolomic and network analysis on mice lungs. Finally, key targets were then validated by Western blotting. GJC aqueous extract effectively alleviated the onset and progression of lung fibrosis in PF mice by inhibiting inflammatory responses and regulating oxidative stress levels. Integrating serum metabolomics and network analyses showed the arachidonic acid (AA) pathway to be the most important metabolic pathway of GJC aqueous extract against PF. Further validation of AA pathway protein levels showed a significant rise in the levels of ALOX5, PTGS2, CYP2C9, and PLA2G2A in PF lungs. GJC aqueous extract treatment regulated the above changes in metabolic programming. In conclusion, GJC is a promising botanical drug to delay the onset and progression of PF mice. The primary mechanism of action is associated with the comprehensive regulation of metabolites and protein expression related to the AA metabolic pathway. Full article