Clinical Features of COVID-19 Patients with Diabetes and Secondary Hyperglycemia

Lower odds of COVID-19-related mortality in hospitalised patients with type II diabetes mellitus: A single-centre study

BACKGROUND

COVID-19 infection in patients with type 2 diabetes mellitus (T2DM) -a chronic illness in Lebanon-is not well described.

METHODS

This was a single-centre retrospective observational study of 491 patients, including 152 patients with T2DM, who were hospitalised for COVID-19 between 20 August 2020 and 21 April 2021. Data on clinical characteristics, laboratory and radiological findings and outcomes were collected from the electronic medical records. Clinical characteristics and in-hospital mortality between patients with and without T2DM infected with COVID-19 using multivariate analysis were compared.

RESULTS

Patients with T2DM were significantly older than those without T2DM (mean age, 68.7 vs. 60.3 years). Patients with T2DM were more likely to present with a body temperature of <38.3°C (83.9% vs. 69.9%) and less likely to present with chest pain (3.9% vs. 9.1%) and sore throat (2.0% vs. 6.8%). Patients with T2DM were more likely to be hypertensive (76.35% vs. 41%) and dyslipidaemic (58.6% vs. 25.7%) and had more frequent underlying coronary artery disease (33.6% vs. 12.4%). The rates of patients with creatinine levels of ≥1.17 mg/L and troponin T levels of ≥4 ng/dL were higher in the T2DM group than in the non-T2DM group (30.4% vs. 15% and 93.3% vs. 83.1%, respectively). Patients with T2DM were more likely to be admitted to the intensive care unit (ICU) (34.2% vs. 22.1%), require invasive ventilation (18.4% vs. 10.3%) and receive vasopressors (16.4% vs. 10.0%). Increasing age and the use of invasive ventilation and vasopressors were associated with higher odds of mortality (odds ratio (OR), 1.08, 9.95 and 19.83, respectively), whereas longer ICU stay was associated with lower odds of mortality (OR, 0.38). The odds of mortality were lower in the T2DM group than in the non-T2DM group (OR, 0.27).

CONCLUSION

Among patients hospitalised for COVID-19, those with T2DM were older, presented with milder symptoms and had more comorbidities and higher troponin T levels compared with those without T2DM. Despite the worse clinical course, the patients with T2DM had lower odds of mortality than those without T2DM.

Intervention Effects of Physical Activity on Type 2 Diabetic Patients Potentially Infected with COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has clearly had a great influence on the lifestyles of the population, especially on patients with type 2 diabetes mellitus. During the COVID-19 outbreak, many countries/regions implemented social-isolation measures, leading to an increase in negative behaviors and impairing the capability of diabetic patients to resist COVID-19, ultimately causing severe prognoses. Moreover, as the epidemic progressed, multiple studies emphasized the significance of physical exercise in the management of type 2 diabetic patients infected with COVID-19. In this study, we selected research from 1 December 2019 to 9 August 2023 that focused on COVID-19-infected diabetic patients to investigate the impact of type 2 diabetes on the immune functions, inflammation factor levels, lung injuries, and mental disorders of such patients, as well as to assess the risk of novel coronavirus pneumonia in these patients. Additionally, the effects of high-intensity, moderate-intensity, and low-intensity exercises on novel coronavirus pneumonia infection in type 2 diabetic patients and the mechanisms of the effects of such exercise were considered. We concluded that elderly diabetic patients with COVID-19 should perform low-intensity exercises to facilitate their recoveries. This study offers guidance for a proper understanding of the dangers of diabetes and the use of appropriate measures to reduce the risk of novel coronavirus pneumonia infections in type 2 diabetic patients.

COVID-19 associated coagulopathy: A bibliometric investigation

Infection with SARS-CoV-2 initiates an immune-hemostatic response. While both systems are intimately connected and necessary for an efficient immune response to contain the infection, excessive coagulation activation might exceed the valuable benefits by causing thrombotic consequences and excessive inflammation. This biological response is new to clinicians and researchers, and accordingly, tremendous studies have been conducted on coagulopathy and its relationship to COVID-19 disease during this pandemic. Therefore, it takes a research insight from a bibliometric perspective to determine research hotspots and trends of COVID-19 associated coagulopathy (C19-CA). The analysis relies on the Scopus database for bibliographic content and Visualization of Similarities viewer software to map bibliometric data of C19-CA. Our study finds the most eminent authors, journals, institutions, funding organizations, and countries that publish in the C19-CA. Additionally; this research employs bibliometric analysis of co-authorship, co-citations, bibliographic coupling, and co-occurrence of keywords. A total of 2242 studies were retrieved, and the number of annual publications of C19-CA showed remarkable growth. The top-publishing authors on C19-CA are Smadja, D.M., Diehl, J.L., and Gendron, N (France). The total number of articles published in English in these three years was 1241, with the original article accounting for 99.8% and conference papers accounting for 0.2%. Huazhong University of Science and Technology (China) is the top-productive institution, with the US being the top-publishing country. Journal of Thrombosis and Thrombolysis received the highest number of original articles. The research results were mainly published in the fields of Medicine, Biochemistry, Genetics, and Molecular Biology, Immunology and Microbiology. Yuanyuan Li, who is (China), is the top-collaborating author. China and its authors have the highest number of citations. Keywords' co-occurrence analyses of the authors and all keywords revealed the following themes in C19-CA; abnormal coagulation parameters, pulmonary coagulopathy, venous and arterial thrombotic disorders, distinct features of coagulopathy, inflammation, and thrombosis in COVID-19, and anticoagulants and thrombolytic therapies. By combining bibliometric analysis with VOSviewer software, we identified C19-CA's leaders, collaborating institutions, and research hotspots, as well as give references for future research paths.

Increased risk of new-onset diabetes in patients with COVID-19: a systematic review and meta-analysis

Background

There is growing evidence that patients with COVID-19 are at increased risk of new-onset diabetes. The limited preliminary studies do not provide strong evidence. To assess the association of the SARS-CoV-2 virus with new-onset diabetes and to characterize the population.

Methods

Search PubMed, Embase, Cochrane Library, and Web of Science electronic databases for a limited period from December 2019 to July 2022. Two independent reviewers conducted a thorough review of eligible articles and extracted relevant information. Pooled proportions, risk ratios (RR), and 95% confidence intervals (95% CI) indicated the incidence and risk ratios of events.

Results

The incidence of new-onset diabetes and hyperglycemia in patients with COVID-19 was 5% (P < 0.001) (3 and 30% for new-onset diabetes and hyperglycemia, respectively), with age, ethnicity, time of diagnosis, and study type all having an impact on the incidence (P < 0.05). New-onset diabetes and hyperglycemia were 1.75 times higher in COVID-19 patients than in non-COVID-19 patients. In new-onset diabetes and hyperglycemia population, the percentage of men is 60% (40% for women), with a mortality rate of 17%. The proportion of new-onset diabetes and hyperglycemia after infection with COVID-19 was 25% in men and 14% in women.

Conclusions

The incidence and relative risk of new-onset diabetes and hyperglycemia are elevated after COVID-19 infection, especially in the early COVID-19 and male populations.

Systemic review registration

PROSPERO registration no.: CRD42022382989 https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=382989.

COVID-19 and diabetes: Association intensify risk factors for morbidity and mortality

Diabetes is a condition that affects a large percentage of the population and it is the leading cause of a wide range of costly complications. Diabetes is linked to a multi-fold increase in mortality and when compared to non-diabetics, the intensity and prevalence of COVID-19 ailment among diabetic individuals are more. Since its discovery in Wuhan, COVID-19 has grown rapidly and shown a wide range of severity. Temperature, lymphopenia, non-productive cough, dyspnoea, and tiredness are recognized as the characteristic of individuals infected with COVID-19 disease. In COVID-19 patients, diabetes and other related comorbidities are substantial predictors of disease and mortality. According to a recent study, SARS-CoV-2 (the virus responsible for covid-19 disease) may also lead to direct pancreatic harm, which could aggravate hyperglycemia and potentially cause the establishment of diabetes in formerly non-diabetic individuals. This bidirectional association of COVID-19 and diabetes load the burden on health care professionals throughout the world. It is recommended that gliptin medications be taken moderately, blood glucose levels must be kept under control, ACE inhibitors should be used in moderation, decrease the number of avoidable hospitalizations, nutritional considerations, and some other prevention measures, such as immunization, are highly recommended. SARS-CoV-2 may cause pleiotropic changes in glucose homeostasis, which could exacerbate the pathophysiology of pre-existing diabetes or result in new disease processes.

A Pilot Study on COVID-19 Positive Subjects: An Excerpt of Post-Infection-Pro-Diabetic Disposition & Related Consequences in Correlation to Hepato-Pancreatic Bio-Markers, Pro-Inflammatory Cytokines and Other Risk Factors

COVID-19, a global pandemic that led to increased morbidity and mortality worldwide since its outcome at the end of the year 2019. A newly discovered variant of severe acute respiratory distress syndrome coronavirus-2 (SARS-CoV-2) was the arbitrator for spreading the syndrome by droplet transmission causing multi-organ failure in many occasions. A post-infection-pro-diabetic disposition was found evident in this study with the persistence of hepato-pancreatic aberrations in respect of reference range of tissue specific bio-markers in hospital admitted COVID-19 cases. The results of this study show that hyperglycemia is a risk factor in precipitating disease oriented complications to the patients with COVID-19 disease. A post-infection follow- up on glycemic-index and related complexities is a vital need to the COVID-19 infected convalescent subjects. Implementation of guidelines on social measure and awareness of anti-viral interventions may be the only way to prevent COVID-19 transmission.

Clinical Significance of COVID-19 and Diabetes: In the Pandemic Situation of SARS-CoV-2 Variants including Omicron (B.1.1.529)

Simple Summary

Amidst the dual pandemics of diabetes and coronavirus disease 2019 (COVID-19), with the constant emergence of novel variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a vicious cycle has been created, i.e., a hyperglycemic state contributes to the severe clinical course of COVID-19, which in turn has deleterious effects on glycometabolism and in some cases causes new-onset diabetes. Here, we present a comprehensive review of the current literature on the clinical and experimental findings associated with the interrelationship between diabetes and COVID-19. To control disease outcomes and glucometabolic complications in COVID-19, this issue is still being investigated.

Abstract

The coronavirus disease 2019 (COVID-19) global pandemic, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains uncontrolled, with the spread of emerging variants. According to accumulating evidence, diabetes is one of the leading risk factors for a severe COVID-19 clinical course, depending on the glycemic state before admission and during COVID-19 hospitalization. Multiple factors are thought to be responsible, including an altered immune response, coexisting comorbidity, and disruption of the renin-angiotensin system through the virus–host interaction. However, the precise underlying mechanisms remain under investigation. Alternatively, the focus is currently on the diabetogenic and ketosis-prone potential of SARS-CoV-2 itself, even for probable triggers of stress and steroid-induced hyperglycemia in COVID-19. In this article, we present a comprehensive review of the recent literature on the clinical and experimental findings associated with diabetes and COVID-19, and we discuss their bidirectional relationship, i.e., the risk for an adverse prognosis and the deleterious effects on glycometabolism. Accurate assessments of the incidence of new-onset diabetes induced by COVID-19 and its pathogenicity are still unknown, especially in the context of the circulation of SARS-CoV-2 variants, such as Omicron (B.1.1.529), which is a major challenge for the future.

Immunoregulatory Intestinal Microbiota and COVID-19 in Patients with Type Two Diabetes: A Double-Edged Sword

Coronavirus disease 2019, or COVID-19, is a major challenge facing scientists worldwide. Alongside the lungs, the system of organs comprising the GI tract is commonly targeted by COVID-19. The dysbiotic modulations in the intestine influence the disease severity, potentially due to the ability of the intestinal microbiota to modulate T lymphocyte functions, i.e., to suppress or activate T cell subpopulations. The interplay between the lungs and intestinal microbiota is named the gut-lung axis. One of the most usual comorbidities in COVID-19 patients is type 2 diabetes, which induces changes in intestinal microbiota, resulting in a pro-inflammatory immune response, and consequently, a more severe course of COVID-19. However, changes in the microbiota in this comorbid pathology remain unclear. Metformin is used as a medication to treat type 2 diabetes. The use of the type 2 diabetes drug metformin is a promising treatment for this comorbidity because, in addition to its hypoglycemic action, it can increase amount of intestinal bacteria that induce regulatory T cell response. This dual activity of metformin can reduce lung damage and improve the course of the COVID-19 disease.

Association of serum C-reactive protein (CRP) and D-dimer concentration on the severity of COVID-19 cases with or without diabetes: a systematic review and meta-analysis

INTRODUCTION

Coronavirus disease (COVID-19) is a highly contagious disease that poses major public health risks. Fewer studies link high CRP and D-dimer levels to severe COVID-19 infection. Therefore, this study investigates the association of serum CRP and D-dimer concentration with COVID-19 severity in diabetic and non-diabetic patients.

AREAS COVERED

Relevant published articles were identified using electronic search engines, such as Google Scholar, PubMed, Springer, Science Direct, and Researchgate. A total of 29 articles reporting on 15,282 patients (4,733 diabetes and 10,549 non-diabetes) were included in this systematic review and meta-analysis. RevMan V5.4, STATA V14 software, and SPSS V25 were used for the meta-analysis. Egger's regression and Begg-Mazumdar's test were used for assessing publication bias. The pooled result of all studies revealed that serum CRP (Standard mean difference (SMD) 0.41 mg/L; P < 0.0001; I2 93%) and D-dimer (SMD 0.32 mg/L; P < 0.0001; I2 83%) concentration was significantly higher in COVID-19 diabetic patients. The prevalence of COVID-19 infection was comparatively higher in male diabetic patients (OR 2.41; P < 0.00001; I2 88%). There was no publication bias. CRP and D-dimer rose with age in COVID-19 diabetic and non-diabetic patients.

EXPERT OPINION

Overall, the serum CRP and D-dimer concentration in COVID-19 diabetic patients was significantly higher than non-diabetic patients indicating severe illness.

The underlying mechanisms for severe COVID-19 progression in people with diabetes mellitus: a critical review

Diabetes mellitus (DM) has a high incidence of comorbidities among patients with severe coronavirus disease 2019 (COVID-19). The elevated prevalence of DM in the world population makes it a significant risk factor because diabetic individuals appear to be prone to clinical complications and have increased mortality rates. Here, we review the possible underlying mechanisms involved in DM that led to worse outcomes in COVID-19. The impacts of hyperglycemia side effects, secondary comorbidities, weakened innate and adaptive immunity, chronic inflammation, and poor nutritional status, commonly present in DM, are discussed. The role of the SARS-CoV-2 receptor and its polymorphic variations on higher binding affinity to facilitate viral uptake in people with DM were also considered. Clinical differences between individuals with type 1 DM and type 2 DM affected by COVID-19 and the potential diabetogenic effect of SARS-CoV-2 infection were addressed.

D-dimer Level and Diabetes in the COVID-19 Infection

Introduction

Diabetes is the most common of comorbidity in patients with SARS-COV-2 pneumonia. Coagulation abnormalities with D-dimer levels are increased in this disease.

Objectifs

We aimed to compare the levels of D-dimer in diabetic and non-diabetic patients with COVID 19. A link between D-dimer and mortality has also been established.

Materials

A retrospective study was carried out at the University Hospital Center of Oujda (Morocco) from November 01st to December 01st, 2020. Our study population was divided into two groups: a diabetic group and a second group without diabetes to compare clinical and biological characteristics between the two groups. In addition, the receiver operator characteristic curve was used to assess the optimal D-dimer cut-off point for predicting mortality in diabetics.

Results

201 confirmed-COVID-19-patients were included in the final analysis. The median age was 64 (IQR 56-73), and 56% were male. Our study found that D-dimer levels were statistically higher in diabetic patients compared to non-diabetic patients. (1745 vs 845 respectively, P = 0001). D-dimer level > 2885 ng/mL was a significant predictor of mortality in diabetic patients with a sensitivity of 71,4% and a specificity of 70,7%.

Conclusion

Our study found that diabetics with COVID-19 are likely to develop hypercoagulation with a poor prognosis.

New-onset diabetes in COVID-19 and clinical outcomes: A systematic review and meta-analysis

BACKGROUND

Diabetes mellitus (DM) is associated with adverse clinical outcomes and high mortality in patients with coronavirus disease 2019 (COVID-19). The relationship between diabetes and COVID-19 is known to be bidirectional.

AIM

To analyze the rate of new-onset diabetes in COVID-19 patients and compare the clinical outcomes of new-onset diabetes, pre-existing diabetes, hyperglycemic, and non-diabetes among COVID-19 patients.

METHODS

We used the Meta-analysis of Observational Studies in Epidemiology statement for the present meta-analysis. Online databases were searched for all peer-reviewed articles published until November 6, 2020. Articles were screened using Covidence and data extracted. Further analysis was done using comprehensive meta-analysis. Among the 128 studies detected after thorough database searching, seven were included in the quantitative analysis. The proportion was reported with 95% confidence interval (CI) and heterogeneity was assessed using I².

RESULTS

Analysis showed that 19.70% (CI: 10.93-32.91) of COVID-19 patients had associated DM, and 25.23% (CI: 19.07-32.58) had associated hyperglycemia. The overall mortality rate was 15.36% (CI: 12.57-18.68) of all COVID-19 cases, irrespective of their DM status. The mortality rate was 9.26% among non-diabetic patients, 10.59% among patients with COVID-19 associated hyperglycemia, 16.03% among known DM patients, and 24.96% among COVID-19 associated DM patients. The overall occurrence of adverse events was 20.52% (CI: 14.21-28.70) among COVID-19 patients in the included studies, 15.29% among non-diabetic patients, 20.41% among patients with COVID-19 associated hyperglycemia, 20.69% among known DM patients, and 45.85% among new-onset DM. Meta-regression showed an increasing rate of mortality among new hyperglycemic patients, known diabetics, and new-onset DM patients in comparison to those without diabetes.

CONCLUSION

A significantly higher rate of new onset DM and hyperglycemia was observed. Higher mortality rates and adverse events were seen in patients with new-onset DM and hyperglycemia than in the non-diabetic population.

Chronic Diseases as a Predictor for Severity and Mortality of COVID-19: A Systematic Review With Cumulative Meta-Analysis

Introduction: Given the ongoing coronavirus disease 2019 (COVID-19) pandemic and the consequent global healthcare crisis, there is an urgent need to better understand risk factors for symptom deterioration and mortality among patients with COVID-19. This systematic review aimed to meet the need by determining the predictive value of chronic diseases for COVID-19 severity and mortality.

Methods: We searched PubMed, Embase, Web of Science, and Cumulative Index to Nursing and Allied Health Complete to identify studies published between December 1, 2019, and December 31, 2020. Two hundred and seventeen observational studies from 26 countries involving 624,986 patients were included. We assessed the risk of bias of the included studies and performed a cumulative meta-analysis.

Results: We found that among COVID-19 patients, hypertension was a very common condition and was associated with higher severity, intensive care unit (ICU) admission, acute respiratory distress syndrome, and mortality. Chronic obstructive pulmonary disease was the strongest predictor for COVID-19 severity, admission to ICU, and mortality, while asthma was associated with a reduced risk of COVID-19 mortality. Patients with obesity were at a higher risk of experiencing severe symptoms of COVID-19 rather than mortality. Patients with cerebrovascular disease, chronic liver disease, chronic renal disease, or cancer were more likely to become severe COVID-19 cases and had a greater probability of mortality.

Conclusions: COVID-19 patients with chronic diseases were more likely to experience severe symptoms and ICU admission and faced a higher risk of mortality. Aggressive strategies to combat the COVID-19 pandemic should target patients with chronic diseases as a priority.

Effect of plasma glucose at admission on COVID-19 mortality: experience from a tertiary hospital

OBJECTIVE

Plasma glucose has been correlated with in-hospital mortality among many diseases including infections. We aimed to study the plasma glucose at the admission of hospitalized patients with COVID-19 at a tertiary care referral hospital at Jodhpur, India and its relation with mortality.

DESIGN

A hospital-based clinical study of plasma glucose of COVID-19 patients conducted from May 15 to June 30, 2020 after ethical approval.

MEASUREMENTS

Random blood samples at admission were collected for plasma glucose, interleukin-6 (IL6) and high sensitivity C-reactive protein (hsCRP) after written informed consent was obtained. Plasma glucose was analyzed by the automated analyzer, IL6 by chemiluminescent immunoassay and hsCRP by immune-turbidimetric assay.

RESULTS

A total of 386 patients were studied (female 39.6%); 11.1% had severe disease and 4.1% expired. There were 67 (17.4%) patients with known diabetes mellitus (DM). Patients with a history of DM had three times higher mortality (6/67, 9%) than those without DM (10/309, 3.1%). Patients with moderate and severe disease according to ICMR and WHO grading had higher plasma glucose than those with asymptomatic or mild disease (P < 0.0001). Plasma glucose levels at admission were significantly higher in non-survivors when compared to those who survived (297 ± 117 vs 131 ± 73; P < 0.0001). COVID-19 patients showed increased mortality with incremental plasma glucose levels. The hazard ratio for mortality was 1.128 (95% CI 0.86-14.860), 1.883 (95% CI 0.209-16.970), and 4.005 (95% CI 0.503-32.677) in random plasma glucose group of >100-200, >200-300 and >300 mg/dL, respectively, compared to those with random plasma glucose of <100 mg/dL at admission. Plasma glucose was strongly correlated with hsCRP (P < 0.001) and IL6 (P < 0.0001).

CONCLUSIONS

Plasma glucose at admission in hospitalized COVID-19 patients is a strong predictor of mortality.

Impact of I/D polymorphism of angiotensin-converting enzyme 1 (ACE1) gene on the severity of COVID-19 patients

Severe acute respiratory syndrome corona virus-2 (SARS-CoV-2) has first emerged from China in December 2019 and causes coronavirus induced disease 19 (COVID-19). Since then researchers worldwide have been struggling to detect the possible pathogenesis of this disease. COVID-19 showed a wide range of clinical behavior from asymptomatic to severe acute respiratory disease syndrome. However, the etiology of susceptibility to severe lung injury is not yet fully understood. Angiotensin-converting enzyme1 (ACE1) convert angiotensin I into Angiotensin II that was further metabolized by ACE 2 (ACE2). The binding ACE2 receptor to SARS-CoV-2 facilitate its enter into the host cell. The interaction and imbalance between ACE1 and ACE2 play a crucial role in the pathogenesis of lung injury. Thus, the aim of this study was to investigate the association of ACE1 I/D polymorphism with severity of Covid-19.

The study included RT-PCR confirmed 269 cases of Covid-19. All cases were genotyped for ACE1 I/D polymorphism using polymerase chain reaction and followed by statistical analysis (SPSS, version 15.0).

We found that ACE1 DD genotype, frequency of D allele, older age (≥46 years), unmarried status, and presence of diabetes and hypertension were significantly higher in severe COVID-19 patient. ACE1 ID genotype was significantly independently associated with high socio-economic COVID-19 patients (OR: 2.48, 95% CI: 1.331–4.609).

These data suggest that the ACE1 genotype may impact the incidence and clinical outcome of COVID-19 and serve as a predictive marker for COVID-19 risk and severity.

Diabetes mellitus as a comorbidity in COVID-19 infection in the United Arab Emirates

OBJECTIVES

To compare risk factors and clinical outcomes among COVID-19 patients with or without diabetes in the United Arab Emirates (UAE).

METHODS

Data of 350 COVID-19 positive patients, admitted to Al Kuwait Hospital in Dubai, UAE, from February to May 2020 was collected retrospectively, including demographic data, clinical symptoms, blood tests, as well as radiographical assessments, and clinical outcomes of COVID-19. The design of the study is a retrospective cohort study.

RESULTS

COVID-19 patients with diabetes belong to an older age group, had a higher percentage of male patients, exhibited more lymphopenia and neutrophilia, and higher ferritin levels. Additionally, patients with diabetes presented fever and shortness of breath (SOB), displayed more bilateral airspace consolidation and opacities in their chest x-ray and CT scans, compared to non-diabetics. A higher percentage of critical, ICU-admitted, and death of COVID-19 cases in the diabetic group was also reported. This was along with a concomitant increase in C-reactive protein, procalcitonin, and lactate dehydrogenase levels.

CONCLUSIONS

Diabetes is considered a comorbidity as diabetic patients showed more severe COVID-19 symptoms that led to critical clinical outcomes such as ICU admission and death.

COVID-19: Integrating the Complexity of Systemic and Pulmonary Immunopathology to Identify Biomarkers for Different Outcomes

In the last few months, the coronavirus disease 2019 (COVID-19) pandemic has affected millions of people worldwide and has provoked an exceptional effort from the scientific community to understand the disease. Clinical evidence suggests that severe COVID-19 is associated with both dysregulation of damage tolerance caused by pulmonary immunopathology and high viral load. In this review article, we describe and discuss clinical studies that show advances in the understanding of mild and severe illness and we highlight major points that are critical for improving the comprehension of different clinical outcomes. The understanding of pulmonary immunopathology will contribute to the identification of biomarkers in an attempt to classify mild, moderate, severe and critical COVID-19 illness. The interface of pulmonary immunopathology and the identification of biomarkers are critical for the development of new therapeutic strategies aimed to reduce the systemic and pulmonary hyperinflammation in severe COVID-19.