Studying the dynamics changes of neutrophils during innate immune response in coronavirus 2019 (COVID-19) can help understand the pathogenesis of this disease. The aim of the study was to assess the usefulness of new neutrophil activation parameters: Immature Granulocyte (IG), Neutrophil Reactivity Intensity (NEUT-RI), Neutrophil Granularity Intensity (NEUT-GI), and data relating to granularity, activity, and neutrophil volume (NE-WX, NE-WY, NE-WZ) available in hematology analyzers to distinguish convalescent patients from patients with active SARS-CoV-2 infection and healthy controls (HC). The study group consisted of 79 patients with a confirmed positive RT-PCR test for SARS-CoV2 infection, 71 convalescent patients, and 20 HC. We observed leukopenia with neutrophilia in patients with active infection compared to convalescents and HC. The IG median absolute count was higher in convalescent patients than in COVID-19 and HC (respectively, 0.08 vs. 0.03 vs. 0.02, p < 0.0001). The value of the NEUT-RI parameter was the highest in HC and the lowest in convalescents (48.3 vs. 43.7, p < 0.0001). We observed the highest proportion of NE-WX, NE-WY, and NE-WZ parameters in HC, without differences between the COVID-19 and convalescent groups. New neutrophil parameters can be useful tools to assess neutrophils’ activity and functionalities in the immune response during infection and recovery from COVID-19 disease.

Background/Objectives: Coronavirus disease 2019 (COVID-19) course may differ among individuals—in particular, those with comorbidities may have severe pneumonia, requiring oxygen supplementation or mechanical ventilation. Post-COVID-19 long-term structural changes in imaging studies can contribute to persistent respiratory disturbance. This study aimed to investigate COVID-19 sequels affecting the possibility of persistent structural lung tissue abnormalities and their influence on the respiratory function of peripheral airways and gas transfer. Methods: Patients were divided into two groups according to severity grades described by the World Health Organization. Among the 176 hospitalized patients were 154 patients with mask oxygen supplementation and 22 patients with high-flow nasal cannula (HFNC) or mechanical ventilation. All tests were performed at 3, 6, and 9 months post-hospitalization. Results: Patients in the severe/critical group had lower lung volumes in FVC, FVC%, FEV1, FEV1%, LC, TLC%, and DLCO% at three months post-hospitalization. At 6 and 9 months, neither group had significant FVC and FEV1 value improvements. The MEF 25–75 values were not significantly higher in the mild/moderate group than in the severe/critical group at three months. There were weak significant correlations between FVC and FEV1, MEF50, MEF 75, plethysmography TLC, disturbances in DLCO, and total CT abnormalities in the severe/critical group at three months. In a mild/moderate group, there was a significant negative correlation between the spirometry, plethysmography parameters, and CT lesions in all periods. Conclusions: Persistent respiratory symptoms post-COVID-19 can result from fibrotic lung parenchyma and post-infectious stenotic small airway changes not visible in CT, probably due to persistent inflammation.

SARS-CoV-2 infection triggers a strong inflammatory response, and persistent symptoms after recovery are thought to reflect prolonged systemic dysregulation. However, mechanisms underlying long COVID remain unclear. This study evaluated longitudinal changes in cytokine hematological and biochemical parameters up to nine months after hospitalization for COVID-19 and examined their relationship with persistent symptoms, vaccination status, and the occurrence of comorbidities. Long COVID patients showed sustained elevations in IL-2, IL-6, IL-10, IL-17A, CXCL9, TNF-α, and IFN-γ compared with healthy controls, exhibiting heterogeneous temporal trajectories. Specifically, levels of IL-2, IL-10, TNF-α, and creatinine continued to increase over time, whereas IFN-γ, LDH, CCL2, CXCL9, and CXCL10 declined. Other parameters exhibited greater variability without a uniform longitudinal pattern. IL-6 demonstrated consistently high diagnostic performance in distinguishing individuals after COVID-19 from healthy controls (AUC > 0.82). Aging substantially affects cytokine profiles and systemic inflammatory status; therefore, residual age-related confounding cannot be fully excluded despite statistical adjustment. Although symptoms such as fatigue, cough, and dyspnea were still reported at nine months, no stable associations were identified between cytokine concentrations and clinical manifestations. These findings indicate that while immune alterations persist long after acute infection, systemic cytokine measurements alone may be insufficient to explain the presence or persistence of symptoms. The results suggest that long COVID reflects multifactorial processes extending beyond systemic inflammation and highlight the need for further research into mechanisms driving long-term long COVID sequelae.

Background: Some hospitalized patients develop severe pulmonary complications with unknown post COVID-19 outcomes. Objective: To investigate the effect of CT pulmonary abnormality, lung function, and the possibility of small airway dysfunction after COVID-19. Methods: A prospective analysis was performed on 154 patients with COVID-19. These patients were assessed 3, 6, and 9 months after hospital discharge. HRCT abnormalities were calculated by semiquantitative total CT score (0–25) by adding five lobes scores (0–5) according to the range of lesion involvement. Lung function test (LFT) was measured, including forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), forced expiratory volume in the first second to expiratory vital capacity (FEV1/FVC), maximum mid-expiratory flow rate (MEF 25-75), peak expiratory flow rate (PEF), and total lung capacity (TLC), residual value (RV), carbon monoxide dispersion (DLCO). Results: There were no differences in LFT parameters between analyzed periods and between both examined groups. The CT abnormalities were the highest after 3 months in both groups and significant correlations with DLCO and MEF 25-50 were observed in severe/critical patients. In the latter observational period, the significant correlations occurred only between TLC, DLCO, MEF- 25-75 in moderate group and FVC and FEV1 in severe/critical group. Conclusions: The significant association between functional lungs and CT radiographic abnormalities observed at 6 and 9 months, especially in the moderate group, may be related potentially due to the small airway disease and lung parenchyma. This was likely due to the different treatment approaches based on the disease severity.

Background/Objective: Malnutrition is common in hospitalized patients and worsens clinical outcomes, particularly in coronavirus disease 2019 (COVID-19), in which inflammation and metabolic disruption contribute to nutritional decline. Thus, identifying simple and accessible markers is essential for early detection and intervention to prevent further deterioration. This study aimed to investigate biochemical and body composition changes during COVID-19 hospitalization and identify key features of hospital-acquired nutritional status disorders. Methods: We conducted a prospective, single-center, observational study of 66 patients hospitalized with COVID-19 between December 2020 and June 2021. Biochemical markers and body composition parameters were measured at admission and at discharge. Deterioration of nutritional status was defined as a weight loss of more than 3% during hospitalization. Results: A total of 66 patients (61% male, aged 56.7 ± 13.4 years; 39% female, aged 58.8 ± 12.0 years) were included. Deterioration of nutritional status was observed in 20 (30%) individuals, more likely in men (OR 7.94, 95% CI: 1.28–49.08) and patients with longer hospitalization (OR 1.30 per day, 95% CI: 1.08–1.57). Weight loss was primarily characterized by a reduction in adipose tissue mass, whereas lean tissue mass did not change significantly. Traditional biochemical markers of malnutrition, including low albumin, prealbumin, or cholesterol levels, were not present in this cohort. Conclusions: Our study highlights the significant burden of nutritional deterioration in hospitalized patients with COVID-19 and demonstrates its atypical presentation, which may limit the effectiveness of standard malnutrition assessment tools.