Long COVID is a recently described entity that is responsible for significant morbidity and that has consequences ranging from mild to life-threatening. The underlying mechanisms are not completely understood, and treatment options are currently limited, as existing data focus more on risk factors and predictors. Smoking has been reported as a risk factor for poor outcomes of acute SARS-CoV-2 infection and seems to also play a role in mediating post-COVID-19 symptoms. We aimed to review relevant work addressing the interaction between smoking and long COVID in order to characterize smoking’s role as a risk factor and possibly identify new research directions. Methods: The PubMed/MEDLINE database was searched using the keywords ‘smoking’, ‘long COVID’, and ‘post-acute COVID’ to identify relevant English-language articles published up to October 2023. Results and conclusions: From the 374 initial hits, a total of 36 papers were deemed relevant to the aim of the review. There was significant variability concerning the ways in which tobacco usage was quantified and reported; still, there is compelling evidence linking smoking to an increased risk of developing manifestations of post-acute-COVID disease. Some clinical conditions, such as dyspnea, cardiovascular symptoms, and cognitive or mental-health impairment, seem to be relatively strongly associated with smoking, while the connection between smoking and upper-airway involvement seems less certain. The available data support recommending smoking cessation as a clinical tool for the prevention of long COVID.

Background: Asthma is a chronic inflammatory airway disease in which oxidative stress and antioxidant imbalance play a critical role in disease progression and therapeutic response. This study aimed to evaluate oxidative stress and antioxidant status in relation to asthma control levels. Methods: A total of 106 patients admitted to the Clinical Hospital of Pulmonary Diseases, Iași, between March and May 2024 were included in this study. Patients were classified into three groups based on asthma control: well-controlled (AB-TCG), partially controlled (AB-PCG), and uncontrolled asthma (AB-UCG). Demographic, biochemical, and hematological parameters were assessed, with attention to oxidative stress markers and antioxidant defenses. Results: The study population was predominantly female (75%), with a mean age ranging from 50.75 to 64.38 years, and the majority residing in rural areas (73–75%). The AB-UCG group showed significantly elevated inflammatory markers, including a white blood cell count of 9.33 × 10³/µL (p = 0.005) and eosinophil percentage of 4.20% (p = 0.03), compared with the other groups. This group also exhibited an unfavorable lipid profile, with increased total cholesterol (207.40 mg/dL) and triglyceride levels (157.21 mg/dL). Oxidative stress was notably higher in the AB-UCG group, as indicated by elevated malondialdehyde (MDA) levels (2.86 mmol/L) versus 2.35 mmol/L in the AB-PCG group (p < 0.005), along with decreased serum uric acid (4.64 mg/dL) and reduced glutathione (GSH) levels (275.41 µmol/L), leading to a lower GSH/GSSG ratio. Environmental exposures, including tobacco smoke and occupational chemicals, were associated with exacerbated oxidative imbalance. Conclusions: The findings highlight the critical involvement of oxidative stress and compromised antioxidant defenses in poorly controlled asthma. Biomarkers such as MDA, white blood cell count, eosinophil percentage, and the GSH/GSSG ratio may act as valuable tools for personalized asthma management and therapeutic monitoring.

The laboratory tests and identification of risk factors such as comorbidities are essential in the management, treatment and prognosis of patients with chronic respiratory diseases. Performing rigorous monitoring among patients with post-COVID-19 syndrome and early identification of risk factors associated with poor prognosis are crucial in improving patient outcomes. In the present study, 182 patients diagnosed with COVID-19 and PCI during 2020–2022 were included. A clinical and epidemiological evaluation was performed for each patient. Laboratory tests at admission included complete blood count, Erythrocyte Sedimentation Rate (ESR) and biochemical tests. Receiver operating curve (ROC) and area under the curve (AUC) were calculated to compare the diagnostic performance of each parameter. Regarding comorbidities, arterial hypertension, diabetes mellitus and obesity were the most frequent ones. In the case of chronic lung diseases, asthma and Chronic Obstructive Pulmonary Disease (COPD) were the most frequent. Pleurisy was found especially in patients with PCI Variations in serum LDH values were observed, especially in severe forms of COVID-19 in 2020, with a mean value of 481.44 U/L, compared to patients with PCI, whose mean values (122 U/L) were within the biological range of reference. High neutrophil/lymphocyte ratio (NLR) values quantified in this study were especially associated with moderate and severe forms of COVID-19 and also PCI. The Spearman correlation coefficient was determined to measure the correlations between the clinical parameters of all investigated subjects. A value of p < 0.05 was considered statistically significant. The statistical results indicated that serum lactate dehydrogenase (LDH), glucose and C-reactive protein (CRP) are sensitive markers with a diagnostic role in COVID-19, and lymphocyte (Ly) count, CRP, ESR and glucose were evidenced to be target markers in PCI. LDH values were observed to be statistically significant (p < 0.005) in patients with COVID-19 and obesity evaluated in 2021, while Ly count was statistically significant (p = 0.05) in patients with PCI and arterial hypertension. Regarding comorbidities, it has been observed that obesity, arterial hypertension and cardiovascular diseases represent risk factors in COVID-19/PCI, associated especially with the severe forms of the disease.

Long COVID-19 or post-COVID infection (PCI) refers to the prolongation of symptoms in people who have been infected with the SARS-CoV-2 virus. Some meta-analysis studies have shown that patients with comorbidities, such as diabetes, obesity or hypertension, have severe complications after infection with the SARS-CoV-2 virus. The presence of chronic respiratory diseases such as bronchial asthma, COPD, pulmonary hypertension or cystic fibrosis increases the risk of developing severe forms of the COVID-19 disease. The risk of developing the severe form of COVID-19 was observed in patients with bronchial asthma being treated with corticosteroids, but also in those hospitalized with severe asthma. The biological variables determined in patients with PCI infection showed changes, especially in the hematological parameters, but also in some inflammatory markers. The aim of this study was to investigate some biological predictors in post-COVID-19 infection in patients with asthma and various comorbidities. In the case of patients diagnosed with moderate and severe forms of COVID-19, the variation in biological tests has shown high concentrations for serum glucose, lactate dehydrogenase and C-reactive protein. Additionally, the calculation of the relative risk (RR) based on the associated comorbidities in patients with PCI points to higher values for patients with asthma, hypertension, diabetes and obesity (RR moderate/severe form = 0.98/1.52), compared to patients with PCI and asthma (RR moderate/severe form = 0.36/0.63). Based on the statistical results, it can be concluded that the alanine aminotransferase (ALT) activity (p = 0.006) and the age of patients (p = 0.001) are the variables that contribute the most to the separation of the four classes of comorbidities considered.

Background: Post-COVID-19 syndrome (PCS) is defined as the persistence or development of new symptoms 3 months after the initial infection with the SARS-CoV-2 virus, these clinical aspects being most often associated with functional respiratory changes, as well as imagistic modifications. This study aimed to evaluate longitudinal changes in pulmonary function among patients with PCS, in relation to the severity of the acute COVID-19 episode and the time elapsed since infection. Methods: A retrospective, observational study was conducted at the Clinical Hospital of Pulmonary Diseases Iași, Romania, between January 2021 and December 2022, including 97 adult patients with confirmed PCS. Demographic, clinical, and functional data were collected from medical records. Pulmonary function tests (PFTs) were performed according to ATS/ERS standards, assessing Forced Vital Capacity (FVC), Forced Expiratory Volume in the First Second (FEV₁), FEV₁/FVC ratio (Tiffeneau Index), Maximal Expiratory Flow at 50% and 25% of FVC (MEF50, MEF25), Diffusing Capacity of the Lung for Carbon Monoxide (adjusted for haemoglobin) (DLCO), Carbon Monoxide Transfer Coefficient (KCO), Alveolar Volume (AV), Total Lung Capacity (TLC) and Residual Volume (RV). Patients were grouped by time elapsed since infection (1–3, 4–7, 9–12, and up to 22 months). Statistical analyses included the Mann–Whitney U test, Spearman’s correlation, ROC curve analysis, and Principal Component Analysis (PCA). Results: A progressive improvement in FVC was observed up to 9–18 months post-infection (p < 0.05), while FEV₁ remained stable, suggesting a predominantly restrictive ventilatory pattern. Patients with moderate acute COVID-19 presented significantly lower FVC%, FEV₁%, DLCO%, and KCO% values compared with those with mild disease (p < 0.05). Diffusion abnormalities (DLCO and KCO) persisted beyond 12 months, indicating lasting alveolar-capillary impairment. ROC analysis identified TLC (AUC = 0.857), AV (AUC = 0.855), and KCO (AUC = 0.805) as the most discriminative parameters for residual dysfunction. PCA revealed three major functional domains—airflow limitation, diffusion capacity, and lung volume—explaining up to 70% of total variance. Conclusions: We are facing the emergence of a new phenomenon, namely a secondary post-COVID-19 pandemic of patients confronting with persistent post-COVID-19 symptoms who present with functional respiratory changes and who require careful monitoring in dynamics, personalized treatments and a multidisciplinary approach.