Single-cell RNA sequencing reveals characteristics of myeloid cells in post-acute sequelae of SARS-CoV-2 patients with persistent respiratory symptoms

Background

Although our understanding of the immunopathology and subsequent risk and severity of COVID-19 disease is evolving, a detailed account of immune responses that contribute to the long-term consequences of pulmonary complications in COVID-19 infection remains unclear. Few studies have detailed the immune and cytokine profiles associated with post-acute sequelae of SARS-CoV-2 infection (PASC) with persistent pulmonary symptoms. The dysregulation of the immune system that drives pulmonary sequelae in COVID-19 survivors and PASC sufferers remains largely unknown.

Results

To characterize the immunological features of pulmonary PASC (PPASC), we performed droplet-based single-cell RNA sequencing (scRNA-seq) to study the transcriptomic profiles of peripheral blood mononuclear cells (PBMCs) from a participant naïve to SARS-CoV-2 (Control) (n=1) and infected with SARS-CoV-2 with chronic pulmonary symptoms (PPASC) (n=2). After integrating scRNA-seq data with a naïve participant from a published dataset, 11 distinct cell populations were identified based on the expression of canonical markers. The proportion of myeloid-lineage cells ([MLCs]; CD14+/CD16+monocytes, and dendritic cells) was increased in PPASC (n=2) compared to controls (n=2). MLCs from PPASC displayed up-regulation of genes associated with pulmonary symptoms/fibrosis, while glycolysis metabolism-related genes were downregulated. Similarly, pathway analysis showed that fibrosis-related (VEGF, WNT, and SMAD) and cell death pathways were up-regulated, but immune pathways were down-regulated in PPASC. Further comparison of PPASC with scRNA-seq data with Severe COVID-19 (n=4) data demonstrated enrichment of fibrotic transcriptional signatures. In PPASC, we observed interactive VEGF ligand-receptor pairs among MLCs, and network modules in CD14+ (cluster 4) and CD16+ (Cluster 5) monocytes displayed a significant enrichment for biological pathways linked to adverse COVID-19 outcomes, fibrosis, and angiogenesis. Further analysis revealed a distinct metabolic alteration in MLCs with a down-regulation of glycolysis/gluconeogenesis in PPASC compared to SARS-CoV-2 naïve samples.

Conclusion

Analysis of a small scRNA-seq dataset demonstrated alterations in the immune response and cellular landscape in PPASC. The presence of elevated MLC levels and their corresponding gene signatures associated with fibrosis, immune response suppression, and altered metabolic states suggests a potential role in PPASC development.

Living with pulmonary sequelae of COVID-19 and the implications for clinical nursing practice: A qualitative systematised review

AIM

To synthesise qualitative research on pulmonary sequelae of COVID-19 and identify patient needs and experiences to develop nursing care strategies.

BACKGROUND

Qualitative research on long COVID by subtype has not yet occurred. As pulmonary sequelae constitute a serious long COVID subtype, exploring patient experience and needs can generate knowledge to guide nursing practice.

DESIGN

Systematised review methodology utilised on a purposive sample of published articles and reported using the PRISMA guidelines and checklists. Searched MEDLINE, Cumulative Index to Nursing and Allied Health, and Google Scholar, for English or French articles published from February 2020 to June 2022; qualitative research with adults recovering from COVID-19 with evidence of pulmonary sequelae.

METHODS

Established principles for data extraction followed related to data reduction, data presentation, data comparison, and conclusion formulation and verification. Analysis was informed by Thorne's Interpretive Description and extended with Meleis' transitions theory, Mishel's uncertainty in illness theory and Moore et al.'s holistic theory of unpleasant symptoms. The quality of included studies was assessed Joanna Briggs Institute critical appraisal tool for qualitative research.

RESULTS

Four articles with six pooled participants provided data to yield three main themes: (1) a novel health-illness transition, (2) lung injury and pulmonary fibrosis as antecedent to illness uncertainty, (3) and pulmonary symptoms that are compounded by fatigue and weakness.

CONCLUSION

Pulmonary sequelae of COVID-19 confers a unique health-illness transition, uncertainties and symptoms that can be addressed by theory informed nursing practice.

RELEVANCE TO CLINICAL PRACTICE

Advocacy, optimising the nurse-patient relationship, offering up-to-date information and addressing uncertainty may help patients cope with pulmonary sequelae, a complex subtype of long COVID with important considerations for clinical nursing care. Despite a lack of evidence-informed clinical pathways, nurses can support patients to understand novel treatments, support discharge planning and acknowledge the synergistic nature of pulmonary symptoms and fatigue to support health-illness transitions.

NO PATIENT OR PUBLIC CONTRIBUTION

This article involved analysis of previously published works.

Exploring the pathologist's role in understanding COVID-19: from pneumonia to long-COVID lung sequelae

The crucial role of pathologists in enhancing our understanding of SARS-CoV-2-related disease, from initial pneumonia manifestations to persistent long COVID lung symptoms, is the focus of this review. Pathological explorations have offered unprecedented insights into the early stages of severe COVID-19, shedding light on the interplay between the virus and subsequent complications, thereby shaping clinical approaches. Growing interest is directed to residual lung abnormalities of COVID-19 survivors. Although various radiological studies reported long-lasting pulmonary changes (e.g., ground glass opacities, reticulations, and bronchiectasis), the true incidence of pulmonary fibrosis and corresponding pathological findings in these patients remains largely unknown. There are a few high-impact and knowledgeable works on late complications in COVID-19 survivors, several coming from explant or autopsy cases, and rare cases from in vivo sampling. The study of biopsy samples has further deepened our knowledge of the aftermath of COVID-19 on lung tissue, uncovering alterations at the cellular level and shifts in vascular and epithelial dynamics. Despite the substantial progress made, future research is needed to devise a uniform strategy for interpreting lung biopsies, with a focus on leveraging advanced tools such as molecular and digital pathology techniques, along with artificial intelligence.

Biomarkers of Fibrosis in Patients with COVID-19 One Year After Hospital Discharge: A Prospective Cohort Study

Beyond the acute infection of coronavirus disease (COVID-19), concern has arisen about long-term effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The aim of our study was to analyze if there is any biomarker of fibrogenesis in patients with COVID-19 pneumonia capable of predicting post-COVID-19 pulmonary sequelae. We conducted a multicenter, prospective, observational cohort study of patients admitted to a hospital with bilateral COVID-19 pneumonia. We classified patients into two groups according to severity, and blood sampling to measure matrix metalloproteinase 1 (MMP-1), MMP-7, periostin, and VEGF and respiratory function tests and high-resolution computed tomography were performed at 2 and 12 months after hospital discharge. A total of 135 patients were evaluated at 12 months. Their median age was 61 (interquartile range, 19) years, and 58.5% were men. We found between-group differences in age, radiological involvement, length of hospital stay, and inflammatory laboratory parameters. Differences were found between 2 and 12 months in all functional tests, including improvements in predicted forced vital capacity (98.0% vs. 103.9%; P = 0.001) and DlCO <80% (60.9% vs. 39.7%; P = 0.001). At 12 months, 63% of patients had complete high-resolution computed tomography resolution, but fibrotic changes persisted in 29.4%. Biomarker analysis demonstrated differences at 2 months in periostin (0.8893 vs. 1.437 ng/ml; P < 0.001) and MMP-7 (8.7249 vs. 15.2181 ng/ml; P < 0.001). No differences were found at 12 months. In multivariable analysis, only 2-month periostin was associated with 12-month fibrotic changes (odds ratio, 1.0013; 95% confidence interval, 1.0006-1.00231; P = 0.003) and 12-month DlCO impairment (odds ratio, 1.0006; 95% confidence interval, 1.0000-1.0013; P = 0.047). Our data suggest that early periostin postdischarge could predict the presence of fibrotic pulmonary changes.

Critical Damage of Lung Parenchyma Complicated with Massive Pneumothorax in COVID-19 Pneumonia

It is already known that Coronavirus disease 2019 (COVID-19) may lead to various degrees and forms of lung parenchyma damage, but some cases take a strikingly severe course that is difficult to manage. We report the case of a 62-year old male, non-obese, non-smoker, and non-diabetic, who presented with fever, chills, and shortness of breath. The infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was diagnosed by real-time Polymerase Chain Reaction. Although the patient had been vaccinated with 2 doses of Pfizer-BioNTech COVID-19 vaccine 7 months earlier and had no risk factors for a severe outcome, serial computed tomography (CT) scan revealed lung involvement progressively extending from an initial 30% to 40% to almost 100% 2.5 months later. The spectrum of lung lesions included at first only ground-glass opacities and some tiny emphysema bullae, but later also bronchiectasis, pulmonary fibrosis, and large emphysema bullae as post-COVID-19 pulmonary sequelae. For fear of severe evolution of superimposed bacterial infection (Clostridoides difficile enterocolits and possibly bacterial pneumonia) the administration of corticosteroids was intermittent. Massive right pneumothorax secondary to bulla rupture, possibly favored by the indispensable high flow oxygen therapy, led to respiratory failure compounded by hemodynamic instability, and ultimately to the patient's final demise. COVID-19 pneumonia may cause severe lung parenchyma damage which requires long-term supplemental oxygen therapy. Beneficial or even lifesaving as it might be, high flow oxygen therapy may nonetheless have deleterious effects too, including the development of bullae that may rupture engendering pneumothorax. Corticosteroid treatment should probably be pursued despite superimposed bacterial infection to limit the viral induced damage to lung parenchyma.

Elevated circulating monocytes and monocyte activation in COVID-19 convalescent individuals

Background

Monocytes and macrophages play a pivotal role in inflammation during acute SARS-CoV-2 infection. However, their contribution to the development of post-acute sequelae of SARS-CoV-2 infection (PASC) are not fully elucidated.

Methods

A cross-sectional study was conducted comparing plasma cytokine and monocyte levels among three groups: participants with pulmonary PASC (PPASC) with a reduced predicted diffusing capacity for carbon monoxide [DLCOc, <80%; (PG)]; fully recovered from SARS-CoV-2 with no residual symptoms (recovered group, RG); and negative for SARS-CoV-2 (negative group, NG). The expressions of cytokines were measured in plasma of study cohort by Luminex assay. The percentages and numbers of monocyte subsets (classical, intermediate, and non-classical monocytes) and monocyte activation (defined by CD169 expression) were analyzed using flow cytometry analysis of peripheral blood mononuclear cells.

Results

Plasma IL-1Ra levels were elevated but FGF levels were reduced in PG compared to NG. Circulating monocytes and three subsets were significantly higher in PG and RG compared to NG. PG and RG exhibited higher levels of CD169+ monocyte counts and higher CD169 expression was detected in intermediate and non-classical monocytes from RG and PG than that found in NG. Further correlation analysis with CD169+ monocyte subsets revealed that CD169+ intermediate monocytes negatively correlated with DLCOc%, and CD169+ non-classical monocytes positively correlated with IL-1α, IL-1β, MIP-1α, Eotaxin, and IFN-γ.

Conclusion

This study present evidence that COVID convalescents exhibit monocyte alteration beyond the acute COVID-19 infection period even in convalescents with no residual symptoms. Further, the results suggest that monocyte alteration and increased activated monocyte subsets may impact pulmonary function in COVID-19 convalescents. This observation will aid in understanding the immunopathologic feature of pulmonary PASC development, resolution, and subsequent therapeutic interventions.

Corrigendum: Phenotypic alteration of low-density granulocytes in people with pulmonary post-acute sequelae of SARS-CoV-2 infection

[This corrects the article DOI: 10.3389/fimmu.2022.1076724.].

Post-COVID-19 sequelae in lungs: retrospective computed tomography analysis in selected tertiary care hospitals of Mangalore

Purpose

The radiological features of COVID-19 during the active disease process are well established, but the radio-logical features in the convalescent and post-recovery period of the disease are still unclear. The objectives of this study are to document and assess the proportion of the residual changes in lung post COVID-19 infection and to look for evidence and the proportion of fibrosis post COVID-19 infection on high-resolution computed tomography (HRCT).

Material and methods

HRCT thorax of COVID-positive cases done during the disease process and in the recovery/post recovery phase were included in the study. Sample Size: 75. Categorical data are represented in the form of frequencies and proportions. The c2 test was used as a test of significance for qualitative data. Continuous data are represented as mean and standard deviation. A p-value (probability that the result is true) of < 0.05 was considered as statistically significant after assuming all the rules of statistical tests.

Results

Initial computed tomography (CT) findings mainly included ground glass opacity (GGO) (93.3%), inter-lobular septal thickening (66.7%), consolidation (52.0%), and fibrotic bands (8.0%). Ninety-two per cent of the CT scans demonstrated some pulmonary change in the follow-up CT. This was mostly in the form of GGO (58%). Approximately 17% of cases showed fibrotic changes in the follow-up CT.

Conclusions

Post-COVID lung sequelae can be present in a significant number of patients. This are mostly seen in patients with severe initial disease and in older patients. Statistically significant post-COVID sequelae changes include GGO, fibrotic bands, and bronchiectasis.

Phenotypic alteration of low-density granulocytes in people with pulmonary post-acute sequalae of SARS-CoV-2 infection

Background

Low-density granulocytes (LDGs) are a distinct subset of neutrophils whose increased abundance is associated with the severity of COVID-19. However, the long-term effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on LDG levels and phenotypic alteration remain unexplored.

Methods

Using participants naïve to SARS-CoV-2 (NP), infected with SARS-CoV-2 with no residual symptoms (NRS), and infected with SARS-CoV-2 with chronic pulmonary symptoms (PPASC), we compared LDG levels and their phenotype by measuring the expression of markers for activation, maturation, and neutrophil extracellular trap (NET) formation using flow cytometry.

Results

The number of LDGs was elevated in PPASC compared to NP. Individuals infected with SARS-CoV-2 (NRS and PPASC) demonstrated increased CD10+ and CD16hi subset counts of LDGs compared to NP group. Further characterization of LDGs demonstrated that LDGs from COVID-19 convalescents (PPASC and NRS) displayed increased markers of NET forming ability and aggregation with platelets compared to LDGs from NP, but no differences were observed between PPASC and NRS.

Conclusions

Our data from a small cohort study demonstrates that mature neutrophils with a heightened activation phenotype remain in circulation long after initial SARS-CoV-2 infection. Persistent elevation of markers for neutrophil activation and NET formation on LDGs, as well as an enhanced proclivity for platelet-neutrophil aggregation (PNA) formation in COVID-19 convalescent individuals may be associated with PPASC prognosis and development.

Combined Silymarin and Cotrimoxazole Therapy Attenuates Pulmonary Fibrosis in Experimental Paracoccidioidomycosis

Paracoccidioidomycosis (PCM), which mainly affects rural workers, is a systemic mycosis caused by the Paracoccidioides genus that induces pulmonary sequelae in most adult patients, causing serious disability and impairing their quality of life. Silymarin is herbal medicine with an effective antifibrotic activity. Considering that in PCM, antifibrotic treatment is still not available in pulmonary fibrosis, we aimed to evaluate combined silymarin and cotrimoxazole (CMX) therapy via the intratracheal route in BALB/c mice infected with P. brasiliensis yeast. After 12 weeks of treatment, the lungs were collected for the determination of fungal burden, production of OH-proline, deposition of collagen fibers, pulmonary concentrations of cytokines, and expression of fibronectin, α-SMA, MMP-2, MMP-9, and TIMP-2. Spleen cell cultures were also performed. Our results showed that infected mice treated with combined silymarin/CMX showed lower deposition of collagen fibers in the lungs and lower pulmonary concentrations of hydroxyproline than the placebo groups. Decreased levels of TGF-β1 and fibronectin and high levels of MMP-2 and IFN-γ were also observed in this group of mice. Collectively, our findings indicate that the combination of antifungal treatment with silymarin has a potent antifibrotic effect associated with an immunomodulatory effect that potentializes the antifungal immune response.

Pulmonary Sequelae in Patients After Recovery From Coronavirus Disease 2019: A Follow-Up Study With Chest CT

Objective: The pulmonary sequelae of coronavirus disease 2019 (COVID-19) have not been comprehensively evaluated. We performed a follow-up study analyzing chest computed tomography (CT) findings of COVID-19 patients at 3 and 6 months after hospital discharge. Methods: Between February 2020 and May 2020, a total of 273 patients with COVID-19 at the Shenzhen Third People's Hospital were recruited and followed for 6 months after discharge. Chest CT scanning was performed with the patient in the supine position at end-inspiration. A total of 957 chest CT scans was obtained at different timepoints. A semi-quantitative score was used to assess the degree of lung involvement. Results: Most chest CT scans showed bilateral lung involvement with peripheral location at 3 and 6 months follow-up. The most common CT findings were ground-glass opacity and parenchymal band, which were found in 136 (55.3%) and 94 (38.2%) of the 246 patients at 3 months follow-up, and 82 (48.2%) and 76 (44.7%) of 170 patients at 6 months follow-up, respectively. The number of lobes involved and the total CT severity score declined over time. The total CT score gradually increased with the increasement of disease severity at both 3 months follow-up (trend test P < 0.001) and 6 months follow-up (trend test P < 0.001). Patients with different disease severity represented diverse CT patterns over time. Conclusions: The most common CT findings were ground-glass opacity and parenchymal bands at the 3 and 6 months follow-up. Patients with different disease severity represent diverse CT manifestations, indicating the necessary for long-term follow-up monitoring of patients with severe and critical conditions.

Lung Ultrasound as a First-Line Test in the Evaluation of Post-COVID-19 Pulmonary Sequelae

Background: Interstitial lung sequelae are increasingly being reported in survivors of COVID-19 pneumonia. An early detection of these lesions may help prevent the development of irreversible lung fibrosis. Lung ultrasound (LUS) has shown high diagnostic accuracy in interstitial lung disease (ILD) and could likely be used as a first-line test for post-COVID-19 lung sequelae.

Methods: Single-center observational prospective study. Follow-up assessments of consecutive patients hospitalized for COVID-19 pneumonia were conducted 2–5 months after the hospitalization. All patients underwent pulmonary function tests (PFTs), high-resolution computed tomography (HRCT), and LUS. Radiological alterations in HRCT were quantified using the Warrick score. The LUS score was obtained by evaluating the presence of pathological B-lines in 12 thoracic areas (range, 0–12). The correlation between the LUS and Warrick scores was analyzed.

Results: Three hundred and fifty-two patients who recovered from COVID-19 pneumonia were recruited between July and September 2020. At follow-up, dyspnea was the most frequent symptom (69.3%). FVC and DLCO alterations were present in 79 (22.4%) and 234 (66.5%) patients, respectively. HRCT showed relevant interstitial lung sequelae (RILS) in 154 (43.8%) patients (Warrick score ≥ 7). The LUS score was strongly correlated with the HRCT Warrick score (r = 0.77) and showed a moderate inverse correlation with DLCO (r = −0.55). The ROC curve analysis revealed that a LUS score ≥ 3 indicated an excellent ability to discriminate patients with RILS (sensitivity, 94.2%; specificity, 81.8%; negative predictive value, 94.7%).

Conclusions: LUS could be implemented as a first-line procedure in the evaluation of Post-COVID-19 interstitial lung sequelae. A normal LUS examination rules out the presence of these sequelae in COVID-19 survivors, avoiding the need for additional diagnostic tests such as HRCT.

Evaluation of respiratory anatomical-functional sequelae in patients who recovered from COVID-19

INTRODUCTION

Coronavirus disease 19 (COVID-19) has been a global public health emergency, with 209.89 million cases of infection with SARS-CoV-2 recorded, resulting in 4,401,675 deaths. After recuperation, it is probable that COVID-19 patients have sequelae of the disease. This study aimed to evaluate the respiratory anatomical-functional sequelae in Mexican patients who recovered from COVID-19.

METHODOLOGY

This study included twenty-four patients who recovered from COVID-19 and eight non-infected patients (controls). Participants were screened for SARS-CoV-2 and the presence of IgM/IgG antibodies. Pulmonary function and lung anatomical abnormalities were evaluated by spirometry and computerized tomography.

RESULTS

A total of 45.8% of the patients had pulmonary function with obstructive patterns: 70.8% of recovered cases had COVID-19 Reporting and Data System (CO-RADS) 1, 20.8% CO-RADS 3 and 16.7% CO-RADS 4. A total of 35.3% of patients with CO-RADS 1 also showed bilateral nodal growth; 70.8% of patients tested positive for IgG and 8.4% for IgG/IgM, and 20.8% tested negative for both antibodies.

CONCLUSIONS

There were respiratory anatomical and functional sequelae in Mexican patients who recovered from COVID-19, with a high occurrence of pulmonary obstructive patterns in the study population. These observations indicate the importance of the routine evaluation of sequelae in Mexican patients who recovered from COVID-19 and the need for strict follow-up to improve the quality of life of these patients.

Immunological Profiling of COVID-19 Patients with Pulmonary Sequelae

Cellular immunity may be involved in organ damage and rehabilitation in patients with coronavirus disease 2019 (COVID-19). We aimed to delineate immunological features of COVID-19 patients with pulmonary sequelae (PS) 1 year after discharge. Fifty COVID-19 survivors were recruited and classified according to radiological characteristics, including 24 patients with PS and 26 patients without PS. Phenotypic and functional characteristics of immune cells were evaluated by multiparametric flow cytometry. Patients with PS had an increased proportion of natural killer (NK) cells and a lower percentage of B cells than patients without PS. Phenotypic and functional features of T cells in patients with PS were predominated by the accumulation of CD4-positive (CD4⁺) T cells secreting interleukin 17A (IL-17A), short-lived effector-like CD8⁺ T cells (CD27-negative [CD27⁻] CD62L⁻), and senescent T cells with excessive secretion of granzyme B/perforin/interferon gamma (IFN-γ). NK cells were characterized by the excessive secretion of granzyme B and perforin and the downregulation of NKP30 and NKP46; highly activated NKT and γδ T cells exhibited NKP30 and TIM-3 upregulation and NKB1 downregulation in patients with PS. However, immunosuppressive cells were comparable between the two groups. The interrelationship of immune cells in COVID-19 was intrinsically identified, whereby T cells secreting IL-2, IL-4, and IL-17A were enriched among CD28⁺ and CD57⁻ cells and cells secreting perforin/granzyme B/IFN-γ/tumor necrosis factor alpha (TNF-α)-expressed markers of terminal differentiation. CD57⁺ NK cells, CD4⁺Perforin⁺ T cells, and CD8⁺ CD27⁺ CD62L⁺ T cells were identified as the independent predictors for residual lesions. Overall, our findings unveil the profound imbalance of immune landscape that may correlate with organ damage and rehabilitation in COVID-19.

Persistence of post-COVID lung parenchymal abnormalities during the three-month follow-up

INTRODUCTION

COVID-19-associated pulmonary sequalae have been increasingly reported after recovery from acute infection. Therefore, we aim to explore the charactersitics of persistent lung parenchymal abnormalities in patients with COVID-19.

MATERIAL AND METHODS

An observational study was conducted in patients with post-COVID lung parenchymal abnormalities from April till September 2020. Patients ≥18 years of age with COVID-19 who were diagnosed as post-COVID lung parenchymal abnormality based on respiratory symptoms and HRCT chest imaging after the recovery of acute infection. Data was recorded on a structured pro forma, and descriptive analysis was performed using Stata version 12.1.

RESULTS

A total of 30 patients with post-COVID lung parenchymal abnormalities were identified. The mean age of patients was 59.1 (SD 12.6), and 27 (90.0%) were males. Four HRCT patterns of lung parenchymal abnormalities were seen; organizing pneumonia in 10 (33.3%), nonspecific interstitial pneumonitis in 17 (56.7%), usual interstitial pneumonitis in 12 (40.0%) and probable usual interstitial pneumonitis in 14 (46.7%). Diffuse involvement was found in 15 (50.0%) patients, while peripheral predominance in 15 (50.0%), and other significant findings were seen in 8 (26.7%) patients. All individuals were treated with corticosteroids. The case fatality rate was 16.7%. Amongst the survivors, 32.0% recovered completely, 36.0% improved, while 32.0% of the patients had static or progressive disease.

CONCLUSION

This is the first study from Southeast Asia that identified post-COVID lung parenchymal abnormalities in patients who had no pre-existing lung disease highlighting the importance of timely recognition and treatment of this entity that might lead to fatal outcome.

Long COVID: Distinction between Organ Damage and Deconditioning

(1) Background: Long COVID syndrome refers to long-term sequelae of the novel viral disease, which occur even in patients with initially mild disease courses. However, there is still little evidence of the actual organic consequences and their frequency, and there is no standardized workup to diagnose long COVID syndrome yet. In this study, we aim to determine the efficiency of a stepwise diagnostic approach for reconvalescent COVID-19 patients with cardiopulmonary symptoms. (2) Methods: The diagnostic workup for long COVID syndrome included three steps. In the first step, the focus was on broad applicability (e.g., blood tests and body plethysmography). In the second step, cardiopulmonary exercise testing (CPET) and cardiac MRI (CMR) were used. The third step was tailored to the individual needs of each patient. The observation period lasted from 22 February to 14 May 2021. (3) Results: We examined 231 patients in our long COVID unit (mean [SD] age, 47.8 [14.9], 132 [57.1%] women). Acute illness occurred a mean (SD) of 121 (77) days previously. Suspicious findings in the first visit were seen in 80 (34.6%) patients, prompting further diagnostics. Thirty-six patients were further examined with CPET and CMR. Of those, 16 (44.4%) had pathological findings. The rest had functional complaints without organ damage (“functional long COVID”). Cardiopulmonary sequelae were found in asymptomatic as well as severe courses of the initial COVID-19 disease. (4) Conclusions: A structured diagnostic pathway for the diagnosis of long COVID syndrome is practicable and rational in terms of resource allocation. With this approach, manifest organ damage can be accurately and comprehensively diagnosed and distinguished from functional complaints.

Pulmonary fibrosis secondary to COVID-19: a narrative review

Introduction: Coronavirus disease 2019 (COVID-19) is still increasing worldwide, and as a result, the number of patients with pulmonary fibrosis secondary to COVID-19 will expand over time. Risk factors, histopathological characterization, pathophysiology, prevalence, and management of post-COVID-19 pulmonary fibrosis are poorly understood, and few studies have addressed these issues.Areas covered:This article reviews the current evidence regarding post-COVID-19 pulmonary fibrosis, with an emphasis on the potential risk factors, histopathology, pathophysiology, functional and tomographic features, and potential therapeutic modalities. A search on the issue was performed in the MEDLINE, Embase, and SciELO databases and the Cochrane library between 1 December 2019, and 25 January 2021. Studies were reviewed and relevant topics were incorporated into this narrative review. Expert opinion: Pulmonary sequelae may occur secondary to COVID-19, which needs to be included as a potential etiology in the current differential diagnosis of pulmonary fibrosis. Therefore, serial clinical, tomographic, and functional screening for pulmonary fibrosis is recommended after COVID-19, mainly in patients with pulmonary involvement in the acute phase of the disease. Further studies are necessary to determine the risk factors, markers, pathophysiology, and appropriate management of post-COVID-19 pulmonary fibrosis.

A Pattern Categorization of CT Findings to Predict Outcome of COVID-19 Pneumonia

Background: As global healthcare system is overwhelmed by novel coronavirus disease (COVID-19), early identification of risks of adverse outcomes becomes the key to optimize management and improve survival. This study aimed to provide a CT-based pattern categorization to predict outcome of COVID-19 pneumonia.

Methods: One hundred and sixty-five patients with COVID-19 (91 men, 4–89 years) underwent chest CT were retrospectively enrolled. CT findings were categorized as Pattern 0 (negative), Pattern 1 (bronchopneumonia pattern), Pattern 2 (organizing pneumonia pattern), Pattern 3 (progressive organizing pneumonia pattern), and Pattern 4 (diffuse alveolar damage pattern). Clinical findings were compared across different categories. Time-dependent progression of CT patterns and correlations with clinical outcomes, i.e.„ discharge or adverse outcome (admission to ICU, requiring mechanical ventilation, or death), with pulmonary sequelae (complete absorption or residuals) on CT after discharge were analyzed.

Results: Of 94 patients with outcome, 81 (86.2%) were discharged, 3 (3.2%) were admitted to ICU, 4 (4.3%) required mechanical ventilation, 6 (6.4%) died. 31 (38.3%) had complete absorption at median day 37 after symptom onset. Significant differences between pattern-categories were found in age, disease severity, comorbidity and laboratory results (all P < 0.05). Remarkable evolution was observed in Pattern 0–2 and Pattern 3–4 within 3 and 2 weeks after symptom-onset, respectively; most of patterns remained thereafter. After controlling for age, CT pattern significantly correlated with adverse outcomes [Pattern 4 vs. Pattern 0–3 [reference]; hazard-ratio [95% CI], 18.90 [1.91–186.60], P = 0.012]. CT pattern [Pattern 3–4 vs. Pattern 0–2 [reference]; 0.26 [0.08–0.88], P = 0.030] and C-reactive protein [>10 vs. ≤ 10 mg/L [reference]; 0.31 [0.13–0.72], P = 0.006] were risk factors associated with pulmonary residuals.

Conclusion: CT pattern categorization allied with clinical characteristics within 2 weeks after symptom onset would facilitate early prognostic stratification in COVID-19 pneumonia.