Comparison of COVID-19 pneumonia during the SARS-CoV-2 Omicron wave and the previous non-Omicron wave in a single facility

High interleukin-6 levels induced by COVID-19 pneumonia correlate with increased circulating follicular helper T cell frequency and strong neutralization antibody response in the acute phase of Omicron breakthrough infection

Background

Acute immune responses to coronavirus disease 2019 (COVID-19) are influenced by variants, vaccination, and clinical severity. Thus, the outcome of these responses may differ between vaccinated and unvaccinated patients and those with and without COVID-19-related pneumonia. In this study, these differences during infection with the Omicron variant were investigated.

Methods

A total of 67 patients (including 47 vaccinated and 20 unvaccinated patients) who were hospitalized within 5 days after COVID-19 symptom onset were enrolled in this prospective observational study. Serum neutralizing activity was evaluated using a pseudotyped virus assay and serum cytokines and chemokines were measured. Circulating follicular helper T cell (cTfh) frequencies were evaluated using flow cytometry.

Results

Twenty-five patients developed COVID-19 pneumonia on hospitalization. Although the neutralizing activities against wild-type and Delta variants were higher in the vaccinated group, those against the Omicron variant as well as the frequency of developing pneumonia were comparable between the vaccinated and unvaccinated groups. IL-6 and CXCL10 levels were higher in patients with pneumonia than in those without it, regardless of their vaccination status. Neutralizing activity against the Omicron variant were higher in vaccinated patients with pneumonia than in those without it. Moreover, a distinctive correlation between neutralizing activity against Omicron, IL-6 levels, and cTfh proportions was observed only in vaccinated patients.

Conclusions

The present study demonstrates the existence of a characteristic relationship between neutralizing activity against Omicron, IL-6 levels, and cTfh proportions in Omicron breakthrough infection.

Inverse association with COVID-19 vaccination status of the incidence of pneumonia after SARS-CoV-2 infection: A nationwide retrospective cohort study

BACKGROUND

Although one of the characteristics of COVID-19 is accompanied by acute pneumonia immediately after infection, large-scale cohort studies focused on this issue are lacking. In addition, there is interest in how COVID-19 vaccinations reduce the incidence of acute pneumonia for people infected with different strains of SARS-CoV-2. Thus, we assess the short-term incidence of pneumonia after COVID-19 with the vaccination and SARS-CoV-2 variants.

METHODS

As data for 2136,751 COVID-19 patients between January 01, 2020 and February 28, 2022 was collected, they were observed for one month from the day of infection. Patients in retrospective cohort study were classified according to doses of the received vaccine and the epidemic phase when SARS-CoV-2 variants prevailed. Multivariable logistic regression analysis calculated adjusted odds ratios (aOR) and 95% confidence intervals (CIs) for the pneumonia risk.

RESULTS

In B.1.1.7-B.1.351, B.1.617.2, and B.1.617.2 variants, the aORs (95% CIs; p-value) for incidence of pneumonia were 0.93 (0.89-0.98; <0.001), 0.74 (0.70-0.78; <0.001), and 0.04 (0.038-0.043; <0.001), respectively, compared to the original strain. More than 80% of patients have received the second and more doses of the vaccine (average age=44.67 years). The aORs (95% CIs; p-value) for pneumonia were 0.61 (0.58-0.64; <0.001), 0.39 (0.38-0.40; <0.001), and 0.18 (0.166-0.184; <0.001) in patients who received the first (N = 68,216), second (N = 898,838), and ≥ third doses (N = 836,173), respectively, compared to unvaccinated patients. According to the received vaccine (second dose of mRNA or viral vector), those who received BNT162b2 and mRNA-1273 (N = 787,980) had lower risk of pneumonia, compared to that in those who received h ChAdOx1 nCov-19 and AD26. COV2-S (N = 89,024).

CONCLUSIONS

Our findings suggest that the second and ≥ third doses (61% and 82% of risk aversion effect increased, respectively) of the COVID-19 vaccine can prevent the COVID-19-related pneumonia, regardless of the variants.

Characteristics of hematological parameters on admission in COVID-19 Omicron variant infected in Chinese population: a large-scale retrospective study

BACKGROUND

The Omicron variant of SARS-CoV-2, currently the most prevalent strain, has rapidly spread in Jingzhou, China, due to changes in the country's epidemic prevention policy, resulting in an unprecedented increase in cases. Previous studies reported hematological parameters' predictive value in COVID-19 severity and prognosis, but their relevance for early diagnosis in patients infected by the Omicron variant, particularly in high-risk pneumonia cases, remains unclear. Our study aimed to evaluate these parameters as early warning indicators for Omicron-infected patients in fever clinics and those with pulmonary infections (PI).

METHODS

A total of 2,021 COVID-19 patients admitted to the fever clinic and infectious disease department of Jingzhou Hospital Affiliated to Yangtze University from November 1, 2022, to December 31, 2022, were retrospectively recruited. Demographic and hematological parameters were obtained from the electronic medical records of eligible patients. These hematological parameters were analyzed by receiver operating characteristic (ROC) curves to determine whether they can be used for early diagnosis of COVID-19 patients in fever clinics and the presence of PI in COVID-19 patients.

RESULTS

Statistical differences in hematological parameters were observed between COVID-19 patients with fever and PI and control groups (P < 0.01). The ROC curve further demonstrated that lymphocyte (LYM) counts, neutrophil (NEU) counts, monocyte-to-lymphocyte ratios (MLR), platelet-to-lymphocyte ratios (PLR), white blood cell counts (WBC), and mean corpuscular hemoglobin concentration (MCHC) were the top 6 indicators in diagnosing Omicron infection with fever, with area under the curve (AUC) values of 0.738, 0.718, 0.713, 0.702, 0.700, and 0.687, respectively (P < 0.01). Furthermore, the mean platelet volume (MPV) with an AUC of 0.764, red blood cell count (RBC) with 0.753, hematocrit (HCT) with 0.698, MLR with 0.694, mean corpuscular hemoglobin (MCH) with 0.676, and systemic inflammation response indexes (SIRI) with 0.673 were the top 6 indicators for the diagnosis of COVID-19 patients with PI (P < 0.01).

CONCLUSIONS

LYM, NEU, MLR, PLR, WBC, and MCHC can serve as potential prescreening indicators for Omicron infection in fever clinics. Additionally, MPV, RBC, HCT, MLR, MCH, and SIRI can predict the presence of PI in COVID-19 patients infected by the Omicron variant.

Odds of COVID-19-associated asthma exacerbations in children higher during Omicron wave

BACKGROUND

We aimed to determine the association of COVID-19 variant wave with asthma exacerbations in children with asthma.

METHODS

We conducted a retrospective cross-sectional study of children in the Western Pennsylvania COVID-19 Registry (WPACR). We extracted data for all children in the WPACR with asthma and compared their acute clinical presentation and outcomes during the Pre-Delta (7/1/20-6/30/21), Delta (8/1/21-12/14/21), and Omicron (12/15/21-8/30/22) waves. We conducted multivariable logistic regression analyses of SARS-CoV-2-associated asthma exacerbations, adjusting for characteristics that have been associated with COVID-19 outcomes in prior studies.

RESULTS

Among 573 children with asthma in the WPACR during the study period, the proportion of children with COVID-19 who had an asthma exacerbation was higher during the Omicron wave than during the prior two variant waves (40.2% vs. 22.6% vs. 26.2%, p = 0.002; unadjusted OR = 2.12 [95% confidence interval (CI) = 1.39-3.22], p < 0.001). In our multivariable regression models, the odds of an asthma exacerbation were 2.8 times higher during the Omicron wave than during prior waves (adjusted OR = 2.80 [95% CI = 1.70-4.61]). Results were similar after additionally adjusting for asthma severity but were no longer significant after additionally adjusting for poor asthma control.

CONCLUSION

The proportion of children with asthma experiencing an asthma exacerbation during SARS-CoV-2 infection was higher during Omicron than prior variant waves, adding to the body of evidence that COVID-19-associated respiratory symptoms vary by variant. These findings provide additional support for vaccination and prevention.

Comparison between original SARS-CoV-2 strain and omicron variant on thin-section chest CT imaging of COVID-19 pneumonia

OBJECTIVES

We investigated different computed tomography (CT) features between Omicron-variant and original-strain SARS-CoV‑2 pneumonia to facilitate the clinical management.

MATERIALS AND METHODS

Medical records were retrospectively reviewed to select patients with original-strain SARS-CoV‑2 pneumonia from February 22 to April 22, 2020, or Omicron-variant SARS-CoV‑2 pneumonia from March 26 to May 31, 2022. Data on the demographics, comorbidities, symptoms, clinical types, and CT features were compared between the two groups.

RESULTS

There were 62 and 78 patients with original-strain or Omicron-variant SARS-CoV‑2 pneumonia, respectively. There were no differences between the two groups in terms of age, sex, clinical types, symptoms, and comorbidities. The main CT features differed between the two groups (p = 0.003). There were 37 (59.7%) and 20 (25.6%) patients with ground-glass opacities (GGO) in the original-strain and Omicron-variant pneumonia, respectively. A consolidation pattern was more frequently observed in the Omicron-variant than original-strain pneumonia (62.8% vs. 24.2%). There was no difference in crazy-paving pattern between the original-strain and Omicron-variant pneumonia (16.1% vs. 11.6%). Pleural effusion was observed more often in Omicron-variant pneumonia, while subpleural lesions were more common in the original-strain pneumonia. The CT score in the Omicron-variant group was higher than that in the original-strain group for critical-type (17.00, 16.00-18.00 vs. 16.00, 14.00-17.00, p = 0.031) and for severe-type (13.00, 12.00-14.00 vs 12.00, 10.75-13.00, p = 0.027) pneumonia.

CONCLUSION

The main CT finding of the Omicron-variant SARS-CoV‑2 pneumonia included consolidations and pleural effusion. By contrast, CT findings of original-strain SARS-CoV‑2 pneumonia showed frequent GGO and subpleural lesions, but without pleural effusion. The CT scores were also higher in the critical and severe types of Omicron-variant than original-strain pneumonia.

A Pictorial Essay Describing the CT Imaging Features of COVID-19 Cases throughout the Pandemic with a Special Focus on Lung Manifestations and Extrapulmonary Vascular Abdominal Complications

With the Omicron wave, SARS-CoV-2 infections improved, with less lung involvement and few cases of severe manifestations. In this pictorial review, there is a summary of the pathogenesis with particular focus on the interaction of the immune system and gut and lung axis in both pulmonary and extrapulmonary manifestations of COVID-19 and the computed tomography (CT) imaging features of COVID-19 pneumonia from the beginning of the pandemic, describing the typical features of COVID-19 pneumonia following the Delta variant and the atypical features appearing during the Omicron wave. There is also an outline of the typical features of COVID-19 pneumonia in cases of breakthrough infection, including secondary lung complications such as acute respiratory distress disease (ARDS), pneumomediastinum, pneumothorax, and lung pulmonary thromboembolism, which were more frequent during the first waves of the pandemic. Finally, there is a description of vascular extrapulmonary complications, including both ischemic and hemorrhagic abdominal complications.

Clinical characteristics of COVID-19 patients infected by the Omicron variants in Macao, China: A cross-sectional study

Background and Aims

The evolving mutants of SARS-CoV-2 have made the COVID-19 pandemic sustained for over 3 years. In 2022, BA.4 and BA.5 were the Omicron variants dominating the spread globally. Although COVID-19 was no longer a Public Health Emergency of International Concern (PHEIC) as announced by WHO, the SARS-CoV-2 variants remain a challenge to global healthcare under the circumstances of withdrawal and loosening of personal protective behavior in the post-quarantine era. This study aims to acknowledge the clinical characteristics caused by Omicron BA.4/BA.5 in COVID-19 naive people and analyze possible factors affecting disease severities.

Methods

In this retrospective study, we report and analyze the clinical features of 1820 COVID-19 patients infected with the BA.4/BA.5 Omicron variants of SARS-CoV-2 during a local outbreak that occurred in Macao SAR, China, from June to July 2022.

Results

A total of 83.5% of patients were symptomatic eventually. The most common symptoms were fever, cough, and sore throat. Hypertension, dyslipidemia, and diabetes mellitus were the leading comorbidities. There were significantly more elderly patients (p < 0.001), more patients with comorbidity (p < 0.001) and more patients without vaccination or not completing the series (p < 0.001) in the "Severe to Critical" group. All deceased patients were elderly with at least three comorbidities and were partial to totally dependent in their daily lives.

Conclusion

Our data are consistent with a milder disease caused by BA.4/5 Omicron variants in the general population, while patients with old age and comorbidities have developed severe to critical diseases. Complete vaccination series and booster doses are effective strategies to reinforce protection against severe diseases and avoid mortality.

Characteristics and Clinical Effectiveness of COVID-19 Vaccination in Hospitalized Patients in Omicron-dominated Epidemic Wave - A Nationwide Study in Japan

OBJECTIVES

Coronavirus disease (COVID-19) was severe in the Delta variant-dominated epidemic wave (fifth wave) in Japan. The clinical characteristics and effectiveness of COVID-19 vaccination are not fully understood in the Omicron variant-dominated wave (sixth and seventh waves), especially in hospitalized patients. We investigated the relationship between vaccination and disease severity in the Omicron-dominated wave and compared these variant-dominated waves.

METHODS

The nationwide COVID-19 database (Japan COVID-19 Task Force) was used to compare clinical characteristics and critical outcome in patients hospitalized from Delta (5^th, N=735) vs Omicron-dominated waves (6^th, N=495; 7^th, N=128).

RESULTS

Patients in the sixth and seventh waves had a lower incidence of critical outcomes and respiratory outcomes, and a higher incidence of bacterial infection, although the mortality rate did not differ significantly between waves. In the sixth and seventh waves, 138 (27.9%) and 29 (22.7%) COVID-19 patients were unvaccinated, respectively. Multivariable analysis adjusted with previously reported factors revealed that the proportion of 1) critical outcomes and 2) respiratory outcomes decreased in a frequency-dependent manner; 1) (the number of vaccinations): 1-2 times, aOR 0.37 (95% CI; 0.20-0.69); 3-4 times: aOR 0.25 (95% CI; 0.11-0.58), 2) 1-2 times, aOR 0.43 (95% CI; 0.27-0.66); 3-4 times: aOR 0.36 (95% CI; 0.21-0.60).

CONCLUSIONS

COVID-19 hospitalized patients with Omicron infections showed a lower incidence of critical outcomes than those with Delta infections, and COVID-19 vaccination may contribute to preventing respiratory failure.

COVID-19 Cluster in the Hematology/Respirology Ward of a University Hospital during the Seventh Wave of the SARS-CoV-2 Pandemic in Japan: A Descriptive Study

Objective Patients with hematological malignancies and solid organ tumors reportedly tend to have a more severe COVID-19 trajectory than do those with other diseases. We studied the clinical features and outcomes of nosocomial SARS-CoV-2 infection during the seventh wave of the pandemic. Methods This study retrospectively described the characteristics of COVID-19 clusters involving patients in the hematology/respirologyward of Kochi Medical School Hospital during the seventh wave of the pandemic of SARS-CoV-2. Patients and Materials A total of 40 individuals, including 25 patients and 15 healthcare workers, were studied. The diagnosis of SARS-CoV-2 infection was based on reverse transcription polymerase chain reaction performed on nasopharyngeal samples. Results Eleven patients had hematological diseases, and 14 had respiratory diseases. Most patients presented with a fever (n = 19) and/or sore throat (n = 10). Lower respiratory tract symptoms and pneumonia were rather infrequent, occurring in two patients. All patients received antivirals. The maximal severities were mild in 21 patients and moderate in 2. Two asymptomatic patients with SARS-CoV-2 infection did not develop symptoms of COVID-19. Cycle threshold values in nasopharyngeal samples were significantly lower in patients with COVID-19 than in those who were asymptomatic at the time of the diagnosis with SARS-CoV-2 infection. All SARS-CoV-2-infected inpatients recovered or did not develop symptoms of COVID-19. Conclusion COVID-19 vaccination, early or preemptive treatment with antivirals, and intrinsic changes in SARS-CoV-2 may have contributed to the more favorable outcomes in our series than in previously reported nosocomial clusters.

Characteristics, Outcomes, and Factors Affecting Mortality in Hospitalized Patients with CAP Due to Different Variants of SARS-CoV-2 and Non-COVID-19 CAP

The study was conducted from October 2020 to March 2022 in a province in southern Thailand. The inpatients with community-acquired pneumonia (CAP) and more than 18 years old were enrolled. Of the 1511 inpatients with CAP, COVID-19 was the leading cause, accounting for 27%. Among the patients with COVID-19 CAP, mortalities, mechanical ventilators, ICU admissions, ICU stay, and hospital costs were significantly higher than of those with non-COVID-19 CAP. Household and workplace contact with COVID-19, co-morbidities, lymphocytopenia and peripheral infiltration in chest imaging were associated with CAP due to COVID-19. The delta variant yielded the most unfavorable clinical and non-clinical outcomes. While COVID-19 CAP due to B.1.113, Alpha and Omicron variants had relatively similar outcomes. Among those with CAP, COVID-19 infection as well as obesity, a higher Charlson comorbidity index (CCI) and APACHE II score were associated with in-hospital mortality. Among those with COVID-19 CAP, obesity, infection due to the Delta variant, a higher CCI and higher APACHE II score were associated with in-hospital mortality. COVID-19 had a great impact on the epidemiology and outcomes of CAP.

Concurrent lung adenocarcinoma hidden among multiple shadows of COVID-19 pneumonia: A rare and instructive case report

A 40-year-old man was admitted with a diagnosis of COVID-19 pneumonia. Although most of multiple ground-glass opacities and consolidations on computed tomography improved, a round ground-glass opacity with consolidation remained unchanged and was suspected to be a part-solid nodule of lung adenocarcinoma. Pathologic diagnosis of resected tumor was papillary adenocarcinoma.

Clinical Profile of COVID-19 Patients Admitted at a Private Hospital During Three Surges in Mandalay, Myanmar

Introduction During the coronavirus disease 2019 (COVID-19) pandemic, private hospitals in Mandalay started to manage COVID-19 infections according to national treatment guidelines since February 2021. Variations of clinical characteristics and their outcomes in different surges could be evaluated in the private hospital. This study aimed to assess the clinical profile and outcomes of COVID-19 patients admitted at a private hospital during three surges in Mandalay. Methods This study is a retrospective record review of the case series of COVID-19 patients admitted at City Hospital, Mandalay. The study was conducted from January to December 2022. All of the hospital records of COVID-19 patients admitted during the second wave from February 2020 to 26 May 2021, the third wave from 27 May 2021 to 27 January 2022, and the fourth wave from 28 January to April 2022 were included in the study. Results A total of 1606 admitted cases were included in the study. The mean with standard deviation (SD) of age was 55.7±18.5, and males were 778 (48.4%). The mean duration of hospital stay in days was 10.8±5.94, 10.6±6.11, and 7.3±2.88 in second, third, and fourth waves, respectively. The mean duration of hospital stay was shortened in the fourth wave. Comorbid conditions with hypertension and/or diabetes diseases were mostly observed in three waves of COVID-19 infection. Fever was the most presented symptom in three waves. Cough, sore throat, and rhinorrhea were observed more in the fourth wave compared with previous waves. Complication with pneumonia (71.3%), liver dysfunction (21.0%), acute respiratory distress syndrome (10.0%), thrombocytopenia (6.2%), acute kidney injury (5.5%), bleeding (3.9%), and pulmonary embolism (2.9%) were investigated. Antiviral treatment such as remdesivir or molnupiravir was used more in the patients of third and fourth waves than those of the second wave. Oxygen therapy (59.9%), prone position (35.5%), non-invasive ventilation (9.5%), invasive ventilation (0.5%), inotropes (4.6%), and renal replacement therapy (1.1%) were recorded in serious cases. Only 7.9% and 9.4% died in the hospital in second and third waves. No mortality was observed in the fourth wave. Conclusions The study recommended that COVID-19 patients with comorbid conditions of hypertension or diabetes and ages 65 and older should be taken with intensive care support at the hospital. This study also concluded that a private hospital in Mandalay could tackle with COVID-19 severe cases in line with national treatment guidelines since the second wave and could provide better management in the fourth wave. Antiviral treatment should be used in severe COVID-19 cases for further emergency management. In conclusion, private hospital involvement in the COVID-19 pandemic is supportive of the healthcare provision in Myanmar in an emergency situation.

Value of Laboratory Indicators in Predicting Pneumonia in Symptomatic COVID-19 Patients Infected with the SARS-CoV-2 Omicron Variant

Background

The pathogenicity of Omicron is different from that of the previous strains. The value of hematological indicators in patients at high risk of Omicron infection remains unclear. We need rapid, inexpensive and widely available biomarkers to guide the early detection of people at risk of pneumonia and to provide early intervention. We aimed to assess the value of hematological indicators as risk factors for pneumonia in symptomatic COVID-19 patients infected with the SARS-CoV-2 Omicron variant.

Patients and Methods

The study enrolled 144 symptomatic COVID-19 patients with Omicron infection. We collected available clinical details, including laboratory tests and CT examinations. Univariate and multivariate logistic analyses and receiver operating characteristic (ROC) curve analyses were used to assess the value of laboratory markers in predicting the development of pneumonia.

Results

Among the 144 patients, 50 (34.7%) had pneumonia. The ROC analysis revealed that the areas under the ROC curve (AUC) for leukocytes, lymphocytes, neutrophils, and fibrinogen were 0.603 (95% confidence interval (CI): 0.501-0.704, P=0.043), 0.615 (95% CI: 0.517-0.712, P=0.024), 0.632 (95% CI: 0.534-0.730, P=0.009) and 0.635 (95% CI: 0.539-0.730, P=0.008), respectively. The AUC for neutrophil to lymphocyte ratio (NLR), monocyte to lymphocyte ratio (MLR), fibrinogen to lymphocyte ratio (FLR), and fibrinogen to D-dimer ratio (FDR) were 0.670 (95% CI: 0.580-0.760, P=0.001), 0.632 (95% CI: 0.535-0.728, P=0.009), 0.669 (95% CI: 0.575-0.763, P=0.001) and 0.615 (95% CI: 0.510-0.721, P=0.023), respectively. Univariate analysis showed that elevated levels of NLR (odds ratio (OR): 1.219, 95% CI: 1.046-1.421, P=0.011), FLR (OR: 1.170, 95% CI: 1.014-1.349, P=0.031) and FDR (OR: 1.131, 95% CI: 1.039-1.231, P=0.005) were significantly correlated with the presence of pneumonia. Multivariate analysis indicated elevated NLR (OR: 1.248, 95% CI: 1.068-1.459, P=0.005) and FDR (OR: 1.160, 95% CI: 1.054-1.276, P=0.002) levels were associated with the existence of pneumonia. The AUC for the combination of NLR and FDR was 0.701 (95% CI: 0.606-0.796, P<0.001, sensitivity 56.0%, specificity 83.0%).

Conclusion

NLR and FDR can predict the presence of pneumonia in symptomatic COVID-19 patients infected with the SARS-CoV-2 Omicron variant.

Attenuation and Degeneration of SARS-CoV-2 Despite Adaptive Evolution

The evolution of severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) has followed similar trends as other RNA viruses, such as human immunodeficiency virus type 1 and the influenza A virus. Rapid initial diversification was followed by strong competition and a rapid succession of dominant variants. Host-initiated RNA editing has been the primary mechanism for introducing mutations. A significant number of mutations detrimental to viral replication have been quickly purged. Fixed mutations are mostly diversifying mutations selected for host adaptation and immune evasion, with the latter accounting for the majority of the mutations. However, immune evasion often comes at the cost of functionality, and thus, optimal functionality is still far from being accomplished. Instead, selection for antibody-escaping variants and accumulation of near-neutral mutations have led to suboptimal codon usage and reduced replicative capacity, as demonstrated in non-respiratory cell lines. Beneficial adaptation of the virus includes reduced infectivity in lung tissues and increased tropism for the upper airway, resulting in shorter incubation periods, milder diseases, and more efficient transmission between people.

Molecular Pathogenesis of Fibrosis, Thrombosis and Surfactant Dysfunction in the Lungs of Severe COVID-19 Patients

The global scope and scale of the SARS-CoV-2 pandemic led to huge amounts of important data from clinical observations and experimental analyses being collected, in particular, regarding the long-term impact of COVID-19 on lung tissue. Visible changes in lung tissue mainly relate to the destruction of the alveolar architecture, dense cellularity, and pulmonary fibrosis with myofibroblast proliferation and collagen deposition. These changes are the result of infection, mainly with virus variants from the first pandemic waves (Alpha to Delta). In addition, proper regulation of immune responses to pathogenic viral stimuli is critical for the control of and recovery from tissue/organ damage, including in the lungs. We can distinguish three main processes in the lungs during SARS-CoV-2 infection: damage or deficiency of the pulmonary surfactant, coagulation processes, and fibrosis. Understanding the molecular basis of these processes is extremely important in the context of elucidating all pathologies occurring after virus entry. In the present review, data on the abovementioned three biochemical processes that lead to pathological changes are gathered together and discussed. Systematization of the knowledge is necessary to explore the three key pathways in lung tissue after SARS-CoV-2 virus infection as a result of a prolonged and intense inflammatory process in the context of pulmonary fibrosis, hemostatic disorders, and disturbances in the structure and/or metabolism of the surfactant. Despite the fact that the new Omicron variant does not affect the lungs as much as the previous variants, we cannot ignore the fact that other new mutations and emerging variants will not cause serious damage to the lung tissue. In the future, this review will be helpful to stratify the risk of serious complications in patients, to improve COVID-19 treatment outcomes, and to select those who may develop complications before clinical manifestation.

Old Age is an Independent Risk Factor for Pneumonia Development in Patients with SARS-CoV-2 Omicron Variant Infection and a History of Inactivated Vaccine Injection

Objective

Analyzing the risk factors for pneumonia development in breakthrough cases with a history of inactivated vaccine injection is important. The present study aimed to investigate the risk factors for pneumonia development during Omicron variant infection.

Design and Methods

The clinical data were retrospectively collected from 187 patients who previously received inactivated vaccine and were infected by the Omicron variant.

Results

Among the 187 patients, 73 had 2 doses of inactivated vaccine injection and the remaining 114 had 3 doses; 19 patients had pneumonia at admission. The univariate logistic analysis showed that age, baseline platelet count, D-dimer level, and CD8⁺ T lymphocyte count were associated with pneumonia development at admission. The multivariate analysis showed that only age was the independent risk factor for pneumonia development (odds ratio = 1.046, 95% confidence interval: 1.003-1.091, P = 0.04). With an optimal cutoff value of 46, 4.4% (4/91) patients in the age <46 years group and 15.63% (15/96) patients in the age ≥46 years group had pneumonia (χ ² = 6.454, P = 0.01). Moreover, age negatively correlated with CD8⁺ T cell count, B cell count, and albumin and uric acid levels (all P < 0.01), while age positively correlated with the glucose level (P < 0.01).

Conclusion

Old age was the only independent risk factor for pneumonia development in patients with Omicron variant infection and a history of inactivated vaccine injection.