Pulmonary Recovery 12 Months after Non-Severe and Severe COVID-19: The Prospective Swiss COVID-19 Lung Study

A comparison of pulmonary function pre and post mild SARS-CoV-2 infection among healthy adults

BACKGROUND

SARS-CoV-2 infection frequently involves the respiratory system and may impact on pulmonary function tests (PFT) of recovered individuals. Studies which compare post-COVID-19 PFT to pre-illness measurements are scarce. The primary objective of this study was to assess the effect of COVID-19 on PFT soon after infection.

METHODS

In this prospective observational study, PFT were measured early following recovery from COVID-19 among healthy military aircrew. Spirometry values were compared to pre-COVID-19 measurements, and abnormality rates of lung volumes and diffusion capacity for carbon monoxide (DLCO) were assessed.

RESULTS

The study included 252 aviators, 97.6% males, mean age 34.9-years, following recovery from SARS-CoV-2 infection. Participants manifested mild symptoms (79.4%) or were asymptomatic (20.6%). Post-COVID-19 spirometry results 10.79 ± 5.67 days following infection were compared to measurements performed 41.3 ± 28.59 months earlier. Pre- and post-COVID-19 results were comparable, with similar minimal abnormalities rates (2% and 4.4%, respectively). In addition, there were no restrictive abnormalities following infection, and just 7.7% of individuals had a marginally low DLCO of 70-80% of predicted.

CONCLUSION

Among vaccinated, healthy adults, mild COVID-19 had no significant impact on PFT early post-infection. The data suggest that systematic PFT testing might not be necessary for asymptomatic healthy individuals who recovered from mild COVID-19.

Post-viral lung diseases: the microbiota as a key player

Viral infections of the respiratory tract can lead to chronic lung injury through immunopathological mechanisms that remain unclear. Communities of commensal bacteria colonising the respiratory tract, known as the respiratory tract microbiota, are altered in viral infections, which can contribute to inflammation, lung epithelial damage and subsequent development of lung disease. Emerging evidence on post-viral lung injury suggests an interplay between viral infections, immune responses and airway microbiota composition in the development of viral-induced lung diseases. In this review, we present the clinical characteristics of post-viral lung injury, along with the underlying immunopathological mechanisms and host-bacteria interactions, with a focus on influenza virus, respiratory syncytial virus and coronaviruses. Additionally, considering the important role of the airway microbiota in viral-induced pulmonary sequelae, we suggest key areas for future research on respiratory microbiota involvement in the development of post-viral lung diseases.

Pulmonary diffusing capacity among individuals recovering from mild to moderate COVID-19: a cross-sectional study

Impaired pulmonary diffusing capacity for carbon monoxide (DLCO) following COVID-19 has been consistently reported among individuals recovering from severe-critical infection. However, most long COVID cases follow non-severe COVID-19. We assessed DLCO among individuals with long COVID recovering from mild to moderate acute illness. A cross-sectional study of adults with long COVID, assessed at a COVID recovery clinic > 3 months following the onset of acute infection, during 2020-2021. Participants subjectively ranked their dyspnea severity based on its impact on their daily living and underwent comprehensive pulmonary function testing (PFT). Clinical correlates for impaired DLCO (defined as < 80%) were assessed using multivariable logistic regression models. A total of 458 individuals, their mean age 45 (SD 16) and 246 (54%) of whom are women, were evaluated at an average of ~ 4 months following acute COVID-19. The most frequent PFT impairment was reduced DLCO, identified among 67 (17%) of the cohort. Clinical correlates of impaired DLCO included women (odds ration [OR] 3.64, 95% confidence interval [CI] 1.78-7.45, p < 0.001), cigarette smoking (OR 2.25, 95% CI 1.14-4.43, p = 0.019), and moderate-severe dyspnea (OR 2.77, 95% CI 1.39-5.50, p = 0.004). BMI inversely correlated with DLCO (OR 0.90, 95% CI 0.85-0.96 per 1 unit, p = 0.002). Impaired DLCO was not uncommon among individuals recovering from mild to moderate COVID-19. Women are at a greater risk, and subjective dyspnea correlated with impaired DLCO. Clinicians can rely on self-reported significant dyspnea to guide further assessment.

Persistent pulmonary impairment after 2 years of COVID-19 infection: An observational study

BACKGROUND

Persistent dyspnoea and pulmonary function impairment are common after coronavirus disease 2019 (COVID-19). However, long-term outcomes beyond 2 years of infection are unknown.

METHODS

In this single-center study, we observed the trend of self-reported dyspnoea and pulmonary functions among subjects attending a post-COVID clinic in India after 2 years of COVID-19 illness. Using logistic regression, we explored the clinico-demographic factors associated with persistent dyspnoea and impaired lung functions beyond 2 years.

RESULTS

Among 231 included subjects (68.8% male) with a mean [standard deviation (SD)] age of 44.8 (13.2) years, 119 (51.5%) had recovered from moderate-to-severe COVID-19. The median [inter-quartile range (IQR)] time intervals from COVID-19 diagnosis (T0) to clinical enrolment (T1) and final follow-up (T2) were 3.3 (1.9-5.5) months and 29.5 (27.2-32.2) months, respectively. Between T1 and T2, the prevalence of self-reported dyspnoea remained stable in the whole cohort (39.4% vs. 36.4%, P = 0.26) but declined in the sub-group with moderate-to-severe COVID-19 (63% vs. 54.6%, P = 0.03). Persistent dyspnoea at T2 was associated with female sex (P = 0.007), moderate-to-severe COVID-19 (P < 0.001), and infection during the delta wave (P < 0.001). At T2, impairment in forced vital capacity (FVC) was seen in 48.1% subjects. Persistently impaired FVC was associated with older age (P value = 0.047), female sex (P value <0.001), and infection during the delta wave (P value = 0.02).

CONCLUSION

Persistent self-reported dyspnoea and impaired pulmonary functions were common in COVID-19 survivors beyond 2 years of infection. Female sex and infection during the delta wave were associated with long-term impairments.

Surviving Critical Care: A Follow-Up Study Assessing Pulmonary Function, Cardiopulmonary Exercise Testing, and Quality of Life in COVID-19-Affected Patients

INTRODUCTION

Survivors of severe COVID-19 face complex challenges and a high degree of pulmonary sequelae. Therefore, we aim to describe their ongoing health burden.

METHODS

In this single-center prospective cohort study, COVID-19 ICU survivors were invited 3 and 6 months after ICU discharge. We examined pulmonary function with pulmonary function tests (PFT) and cardiopulmonary exercise testing (CPET), and we established health-related quality of life (HRQL) and health status (HS) with the EuroQol five-dimension five-level (EQ-5D-5L), the short-form health survey 12 (SF-12), and the modified British Medical Research Council dyspnea scale (mMRC) questionnaires.

RESULTS

Out of the 53 individuals screened, 23 participated in this study. Throughout both assessment points, participants maintained PFT results within range, apart from a decline in the transfer factor of the lung for carbon monoxide (TLCO). CPET showed improved fitness but persistent ventilatory deficiencies, indicated by altered dead space ventilation (VD/VT) and elevated arterial-alveoli gradient for oxygen (AaDO2). HRQL and HS remained compromised, with both physical (PCS) and mental component summary (MCS) scores significantly lower than the standardized norm population scores. Also, there was a rise in the prevalence of issues related to mobility, pain/discomfort, and anxiety/depression, and an increase in reported dyspnea.

CONCLUSION

These results enhance our comprehension of the complex difficulties faced by COVID-19 ICU survivors. Six months post-discharge, CPET revealed the presence of ventilatory insufficiencies. Additionally, there was a decline in HRQL and HS, notably affected by mental health concerns and an increase in the level of dyspnea.

Short- and Long-Term Chest-CT Findings after Recovery from COVID-19: A Systematic Review and Meta-Analysis

While ground-glass opacity, consolidation, and fibrosis in the lungs are some of the hallmarks of acute SAR-CoV-2 infection, it remains unclear whether these pulmonary radiological findings would resolve after acute symptoms have subsided. We conducted a systematic review and meta-analysis to evaluate chest computed tomography (CT) abnormalities stratified by COVID-19 disease severity and multiple timepoints post-infection. PubMed/MEDLINE was searched for relevant articles until 23 May 2023. Studies with COVID-19-recovered patients and follow-up chest CT at least 12 months post-infection were included. CT findings were evaluated at short-term (1-6 months) and long-term (12-24 months) follow-ups and by disease severity (severe and non-severe). A generalized linear mixed-effects model with random effects was used to estimate event rates for CT findings. A total of 2517 studies were identified, of which 43 met the inclusion (N = 8858 patients). Fibrotic-like changes had the highest event rate at short-term (0.44 [0.3-0.59]) and long-term (0.38 [0.23-0.56]) follow-ups. A meta-regression showed that over time the event rates decreased for any abnormality (β = -0.137, p = 0.002), ground-glass opacities (β = -0.169, p < 0.001), increased for honeycombing (β = 0.075, p = 0.03), and did not change for fibrotic-like changes, bronchiectasis, reticulation, and interlobular septal thickening (p > 0.05 for all). The severe subgroup had significantly higher rates of any abnormalities (p < 0.001), bronchiectasis (p = 0.02), fibrotic-like changes (p = 0.03), and reticulation (p < 0.001) at long-term follow-ups when compared to the non-severe subgroup. In conclusion, significant CT abnormalities remained up to 2 years post-COVID-19, especially in patients with severe disease. Long-lasting pulmonary abnormalities post-SARS-CoV-2 infection signal a future public health concern, necessitating extended monitoring, rehabilitation, survivor support, vaccination, and ongoing research for targeted therapies.

Risk of newly diagnosed interstitial lung disease after COVID-19 and impact of vaccination: a nationwide population-based cohort study

Objectives

Previous studies suggested that coronavirus disease 2019 (COVID-19) could lead to pulmonary fibrosis, but the incidence of newly diagnosed interstitial lung disease (ILD) after COVID-19 is unclear. We aimed to determine whether COVID-19 increases the risk of newly diagnosed ILD and whether vaccination against COVID-19 can reduce this risk.

Methods

This retrospective cohort study used data from the Korean National Health Insurance claim-based database. Two study groups and propensity score (PS)-matched control groups were constructed: Study 1: participants diagnosed with COVID-19 (COVID-19 cohort) and their PS-matched controls; Study 2: COVID-19 vaccinated participants (vaccination cohort) and their PS-matched controls.

Results

In Study 1, during a median 6 months of follow-up, 0.50% of the COVID-19 cohort (300/60,518) and 0.04% of controls (27/60,518) developed newly diagnosed ILD, with an incidence of 9.76 and 0.88 per 1,000 person-years, respectively. The COVID-19 cohort had a higher risk of ILD [adjusted hazard ratio (aHR), 11.01; 95% confidence interval (CI), 7.42-16.32] than controls. In Study 2, the vaccination cohort had a lower risk of newly diagnosed ILD than controls (aHR, 0.44; 95% CI, 0.34-0.57).

Conclusion

Using nationwide data, we demonstrated that COVID-19 was associated with a higher incidence rate of newly diagnosed ILD, but that this risk could be mitigated by COVID-19 vaccination.

Proteomic Evolution from Acute to Post-COVID-19 Conditions

Many COVID-19 survivors have post-COVID-19 conditions, and females are at a higher risk. We sought to determine (1) how protein levels change from acute to post-COVID-19 conditions, (2) whether females have a plasma protein signature different from that of males, and (3) which biological pathways are associated with COVID-19 when compared to restrictive lung disease. We measured protein levels in 74 patients on the day of admission and at 3 and 6 months after diagnosis. We determined protein concentrations by multiple reaction monitoring (MRM) using a panel of 269 heavy-labeled peptides. The predicted forced vital capacity (FVC) and diffusing capacity of the lungs for carbon monoxide (DLCO) were measured by routine pulmonary function testing. Proteins associated with six key lipid-related pathways increased from admission to 3 and 6 months; conversely, proteins related to innate immune responses and vasoconstriction-related proteins decreased. Multiple biological functions were regulated differentially between females and males. Concentrations of eight proteins were associated with FVC, %, and they together had c-statistics of 0.751 (CI:0.732-0.779); similarly, concentrations of five proteins had c-statistics of 0.707 (CI:0.676-0.737) for DLCO, %. Lipid biology may drive evolution from acute to post-COVID-19 conditions, while activation of innate immunity and vascular regulation pathways decreased over that period. (ProteomeXchange identifiers: PXD041762, PXD029437).

Residual Lung Abnormalities in Survivors of Severe or Critical COVID-19 at One-Year Follow-Up Computed Tomography: A Narrative Review Comparing the European and East Asian Experiences

The literature reports that there was a significant difference in the medical impact of the coronavirus disease (COVID-19) pandemic between European and East Asian countries; specifically, the mortality rate of COVID-19 in Europe was significantly higher than that in East Asia. Considering such a difference, our narrative review aimed to compare the prevalence and characteristics of residual lung abnormalities at one-year follow-up computed tomography (CT) after severe or critical COVID-19 in survivors of European and East Asian countries. A literature search was performed to identify articles focusing on the prevalence and characteristics of CT lung abnormalities in survivors of severe or critical COVID-19. Database analysis identified 16 research articles, 9 from Europe and 7 from East Asia (all from China). Our analysis found a higher prevalence of CT lung abnormalities in European than in Chinese studies (82% vs. 52%). While the most prevalent lung abnormalities in Chinese studies were ground-glass opacities (35%), the most prevalent lung abnormalities in European studies were linear (59%) and reticular opacities (55%), followed by bronchiectasis (46%). Although our findings required confirmation, the higher prevalence and severity of lung abnormalities in European than in Chinese survivors of COVID-19 may reflect a greater architectural distortion due to a more severe lung damage.

Circulating calprotectin levels four months after severe and non-severe COVID-19

BACKGROUND

Calprotectin is an inflammatory marker mainly released by activated neutrophils that is increased in acute severe COVID-19. After initial recovery, some patients have persistent respiratory impairment with reduced diffusion capacity of the lungs for carbon monoxide (DLCO) months after infection. Underlying causes of this persistent impairment are unclear. We aimed to investigate the correlation between circulating calprotectin, persistent lung functional impairment and intensive care unit (ICU) stay after COVID-19 in two university hospital centres in Switzerland.

METHODS

Calprotectin levels were measured in serum from 124 patients (50% male) from the Bern cohort (post-ICU and non-ICU patients) and 68 (76% male) from the Lausanne cohort (only post-ICU patients) four months after COVID-19. Calprotectin was correlated with clinical parameters. Multivariate linear regression (MLR) was performed to evaluate the independent association of calprotectin in different models.

RESULTS

Overall, we found that post-ICU patients, compared to non-ICU, were significantly older (age 59.4 ± 13.6 (Bern), 60.5 ± 12.0 (Lausanne) vs. 48.8 ± 13.4 years) and more obese (BMI 28.6 ± 4.5 and 29.1 ± 5.3 vs. 25.2 ± 6.0 kg/m2, respectively). 48% of patients from Lausanne and 44% of the post-ICU Bern cohort had arterial hypertension as a pre-existing comorbidity vs. only 10% in non-ICU patients. Four months after COVID-19 infection, DLCO was lower in post-ICU patients (75.96 ± 19.05% predicted Bern, 71.11 ± 18.50% Lausanne) compared to non-ICU (97.79 ± 21.70% predicted, p < 0.01). The post-ICU cohort in Lausanne had similar calprotectin levels when compared to the cohort in Bern (Bern 2.74 ± 1.15 µg/ml, Lausanne 2.49 ± 1.13 µg/ml vs. non-ICU 1.86 ± 1.02 µg/ml; p-value < 0.01). Calprotectin correlated negatively with DLCO (r= -0.290, p < 0.001) and the forced vital capacity (FVC) (r= -0.311, p < 0.001).

CONCLUSIONS

Serum calprotectin is elevated in post-ICU patients in two independent cohorts and higher compared to non-ICU patients four months after COVID-19. In addition, there is a negative correlation between calprotectin levels and DLCO or FVC. The relationship between inflammation and lung functional impairment needs further investigations.

TRIAL REGISTRATION

NCT04581135.

The long-term impact of COVID-19 pneumonia on pulmonary function and exercise capacity

Background

The sequelae of post-coronavirus disease 2019 (COVID-19) have been widely reported. However, the time point of the follow-up time in the previous studies varied ranging from 3-24 months and the interval time of the follow-up time was too long (6 or 12 months). Thus, a shorter interval time during recovery for assessment of the sequelae of post COVID-19 on lung function and exercise capacity is still required. Therefore, this study aims to explore the long-term impact of COVID-19 pneumonia on pulmonary function and exercise capacity.

Methods

A prospective observational study was conducted on post COVID-19 pneumonia at the Lung Health Center, Division of Pulmonary, Critical Care and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand between May 2021 and April 2022. Spirometry, impulse oscillometry (IOS), and fractional exhaled nitric oxide (FeNO) were assessed at 1-, 6-, 9-, and 12-month post-hospital discharge when compared to healthy controls. The six-minute walk test (6-MWT) was also assessed.

Results

Thirty-eight post COVID-19 pneumonia with ages 41.1±14.8 years (52.6% male) and twenty-five healthy controls were enrolled. The %predicted of forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1) were significantly lower in post COVID-19 pneumonia compared to healthy controls at month 1 and month 9. The improvement of %predicted FVC and FEV1 was observed in post COVID-19 pneumonia. The six-minute walk distance (6-MWD) was significantly lower in post COVID-19 pneumonia compared to healthy controls in all visits, while the 6-MWD improved overtime in post COVID-19 pneumonia.

Conclusions

The long term sequelae of post COVID-19 pneumonia on lung function and exercise capacity were observed. Pulmonary function tests and six-minutes walk test are useful tools for detection of long term sequelae of post COVID-19 pneumonia.

Exosomal miR-17-5p, miR-146a-3p, and miR-223-3p Correlate with Radiologic Sequelae in Survivors of COVID-19-Related Acute Respiratory Distress Syndrome

We investigated the association between circulating microRNAs (miRNAs) potentially involved in the lung inflammatory process and fibrosis development among COVID-19-related acute respiratory distress syndrome (ARDS) survivors. At 4 ± 2 months from clinical recovery, COVID-19-related ARDS survivors matched for age, sex, and clinical characteristics underwent chest high-resolution computerized tomography (HRCT) and were selected based on imaging pattern evolution into fully recovered (N = normal), pulmonary opacities (PO) and fibrosis-like lesions (FL). Based on the previous literature, we performed plasma miRNA profiling of exosomal miRNAs belonging to the NLRP3-inflammasome platform with validated (miR-17-5p, miR-223-3p) and putative targets (miR-146a-5p), miRNAs involved in the post-transcriptional regulation of acute phase cytokines (miR128-3p, miR3168, miR125b-2-3p, miR106a-5p), miRNAs belonging to the NLRP4-inflammasome platform (miR-141-3p) and miRNAs related to post-transcriptional regulation of the fibrosis process (miR-21-5p). miR-17-5p, miR-223-3p, and miR-146a-5p were significantly down-regulated in patients with FL when compared to patients with PO. miR-146a-5p was also down-regulated in patients with FL than in N. The expression of the remaining miRNAs did not differ by group. In patients with long-term pulmonary radiological sequelae following COVID-19-related ARDS, a down-regulation of miR-17-5p, miR-146a-3p, and miR-223-3p correlated to fibrosis development in patients showing persistent hyper-reactivity to inflammatory stimulation. Our results support the hypothesis that NLRP3-Inflammasome could be implicated in the process of fibrotic evolution of COVID-19-associated ARDS.

Pulmonary Rehabilitation Outcomes of Post-Acute COVID-19 Patients during Different Waves of the Pandemic

(1) Background: Between the beginning of the coronavirus pandemic and summer 2022, we distinguished four pandemic waves, with different characteristics of the affected patients. This study investigated the impact of patient characteristics on the outcome of inpatient pulmonary rehabilitation (PR). (2) Methods: Using a prospective approach, the characteristics of post-acute COVID-19 patients of the different waves who participated in inpatient PR were compared based on their assessments and results collected as part of PR (Cumulative Illness Rating Scale (CIRS), six-minute walk test (6-MWT), Pulmonary Function Testing (PFT), and Functional Independent Measurement (FIM). (3) Results: A total of 483 patients were included in the analysis (Wave 1 n = 51, Wave 2 n = 202, Wave 3 n = 84, Wave 4 n = 146). Compared to Wave 3 + 4, patients of Wave 1 + 2 were older (69 vs. 63 years; p < 0.001), had a significantly lower CIRS (13.0 vs. 14.7 points; p = 0.004), had significant better PFT (FVC: 73 vs. 68%pred; p = 0.009; DLCO_SB: 58 ± 18 vs. 50 ± 17%pred; p = 0.001), and showed significantly more comorbidities (2.0 vs. 1.6 n/pers.; p = 0.009). Wave 3 + 4 showed significantly greater improvements according to the 6-MWT (147 vs. 188 m; p < 0.001) and the FIM (5.6 vs. 21.1 points; p < 0.001). (4) Conclusions: Patients of the COVID-19 infection waves differed significantly according to their anthropometric data, incidence of comorbidities, and impact of the infection. All cohorts achieved clinically relevant and significant functional improvements during PR, with significant higher improvements in Wave 3 + 4.

Identifying key genes related to inflammasome in severe COVID-19 patients based on a joint model with random forest and artificial neural network

Background

The coronavirus disease 2019 (COVID-19) has been spreading astonishingly and caused catastrophic losses worldwide. The high mortality of severe COVID-19 patients is an serious problem that needs to be solved urgently. However, the biomarkers and fundamental pathological mechanisms of severe COVID-19 are poorly understood. The aims of this study was to explore key genes related to inflammasome in severe COVID-19 and their potential molecular mechanisms using random forest and artificial neural network modeling.

Methods

Differentially expressed genes (DEGs) in severe COVID-19 were screened from GSE151764 and GSE183533 via comprehensive transcriptome Meta-analysis. Protein-protein interaction (PPI) networks and functional analyses were conducted to identify molecular mechanisms related to DEGs or DEGs associated with inflammasome (IADEGs), respectively. Five the most important IADEGs in severe COVID-19 were explored using random forest. Then, we put these five IADEGs into an artificial neural network to construct a novel diagnostic model for severe COVID-19 and verified its diagnostic efficacy in GSE205099.

Results

Using combining P value < 0.05, we obtained 192 DEGs, 40 of which are IADEGs. The GO enrichment analysis results indicated that 192 DEGs were mainly involved in T cell activation, MHC protein complex and immune receptor activity. The KEGG enrichment analysis results indicated that 192 GEGs were mainly involved in Th17 cell differentiation, IL-17 signaling pathway, mTOR signaling pathway and NOD-like receptor signaling pathway. In addition, the top GO terms of 40 IADEGs were involved in T cell activation, immune response-activating signal transduction, external side of plasma membrane and phosphatase binding. The KEGG enrichment analysis results indicated that IADEGs were mainly involved in FoxO signaling pathway, Toll-like receptor, JAK-STAT signaling pathway and Apoptosis. Then, five important IADEGs (AXL, MKI67, CDKN3, BCL2 and PTGS2) for severe COVID-19 were screened by random forest analysis. By building an artificial neural network model, we found that the AUC values of 5 important IADEGs were 0.972 and 0.844 in the train group (GSE151764 and GSE183533) and test group (GSE205099), respectively.

Conclusion

The five genes related to inflammasome, including AXL, MKI67, CDKN3, BCL2 and PTGS2, are important for severe COVID-19 patients, and these molecules are related to the activation of NLRP3 inflammasome. Furthermore, AXL, MKI67, CDKN3, BCL2 and PTGS2 as a marker combination could be used as potential markers to identify severe COVID-19 patients.