Imaging Severity COVID-19 Assessment in Vaccinated and Unvaccinated Patients: Comparison of the Different Variants in a High Volume Italian Reference Center

Abstract

Purpose: To analyze the vaccine effect by comparing five groups: unvaccinated patients with Alpha variant, unvaccinated patients with Delta variant, vaccinated patients with Delta variant, unvaccinated patients with Omicron variant, and vaccinated patients with Omicron variant, assessing the “gravity” of COVID-19 pulmonary involvement, based on CT findings in critically ill patients admitted to Intensive Care Unit (ICU). Methods: Patients were selected by ICU database considering the period from December 2021 to 23 March 2022, according to the following inclusion criteria: patients with proven Omicron variant COVID-19 infection with known COVID-19 vaccination with at least two doses and with chest Computed Tomography (CT) study during ICU hospitalization. Wee also evaluated the ICU database considering the period from March 2020 to December 2021, to select unvaccinated consecutive patients with Alpha variant, subjected to CT study, consecutive unvaccinated and vaccinated patients with Delta variant, subjected to CT study, and, consecutive unvaccinated patients with Omicron variant, subjected to CT study. CT images were evaluated qualitatively using a severity score scale of 5 levels (none involvement, mild: ≤25% of involvement, moderate: 26–50% of involvement, severe: 51–75% of involvement, and critical involvement: 76–100%) and quantitatively, using the Philips IntelliSpace Portal clinical application CT COPD computer tool. For each patient the lung volumetry was performed identifying the percentage value of aerated residual lung volume. Non-parametric tests for continuous and categorical variables were performed to assess statistically significant differences among groups. Results: The patient study group was composed of 13 vaccinated patients affected by the Omicron variant (Omicron V). As control groups we identified: 20 unvaccinated patients with Alpha variant (Alpha NV); 20 unvaccinated patients with Delta variant (Delta NV); 18 vaccinated patients with Delta variant (Delta V); and 20 unvaccinated patients affected by the Omicron variant (Omicron NV). No differences between the groups under examination were found (p value > 0.05 at Chi square test) in terms of risk factors (age, cardiovascular diseases, diabetes, immunosuppression, chronic kidney, cardiac, pulmonary, neurologic, and liver disease, etc.). A different median value of aerated residual lung volume was observed in the Delta variant groups: median value of aerated residual lung volume was 46.70% in unvaccinated patients compared to 67.10% in vaccinated patients. In addition, in patients with Delta variant every other extracted volume by automatic tool showed a statistically significant difference between vaccinated and unvaccinated group. Statistically significant differences were observed for each extracted volume by automatic tool between unvaccinated patients affected by Alpha variant and vaccinated patients affected by Delta variant of COVID-19. Good statistically significant correlations among volumes extracted by automatic tool for each lung lobe and overall radiological severity score were obtained (ICC range 0.71–0.86). GGO was the main sign of COVID-19 lesions on CT images found in 87 of the 91 (95.6%) patients. No statistically significant differences were observed in CT findings (ground glass opacities (GGO), consolidation or crazy paving sign) among patient groups. Conclusion: In our study, we showed that in critically ill patients no difference were observed in terms of severity of disease or exitus, between unvaccinated and vaccinated patients. The only statistically significant differences were observed, with regard to the severity of COVID-19 pulmonary parenchymal involvement, between unvaccinated patients affected by Alpha variant and vaccinated patients affected by Delta variant, and between unvaccinated patients with Delta variant and vaccinated patients with Delta variant.

A Comparative Study of Severity of Covid-19 Infection & their Radiological Findings in Vaccinated and Unvaccinated Individuals

“…Among which people in UAE country are 100% vaccinated & least vaccinated in Nigeria i.e 13%. Significant differences were observed, with respect to severity of COVID-19 pulmonary involvement, between unvaccinated patients and vaccinated patients affected by Alpha variant, and same was observed between unvaccinated patients and vaccinated patients with Delta variant (1) . Pneumonia due to COVID-19 was present in 78% of unvaccinated patients, but only 41% of fully vaccinated patients (P = .003 for the difference between groups) https://www.indjst.org/ which indicates pneumonia was roughly twice as frequent for unvaccinated compared to fully vaccinated patients (2) .…”

“…COVID-19 was emerged in Wuhan city of China in December 2019. Since 2 years after the first described SARS-CoV-2 patient, the pandemic of COVID-19 is still being continued in many countries with new infection waves (1) . Initially, it was caused by Beta variant of SARS-Cov2 virus.…”

COVID-19 chest CT and laboratory features of B.1.617.2 (Delta variant) vs B.1.1.7 (Alpha variant) surge: a single center case-control study

“…However, Granata et al showed no radiological pattern differences among VoC in another retrospective study. Actually, they considered also vaccination as a confounding factor but they enrolled only ICU patients and they did not refer to the clinical history of COVID-19 [22]. In our opinion, this should be considered a bias as only severe cases were hospitalized in ICU.…”

Chest computed tomography findings of the Omicron variants of SARS-CoV-2 with different cycle threshold values

“…The number of patients with patchy consolidation shadows (14.62%), pleural changes (10.77%), and two or more abnormal signs (30.3%) was higher in the low Ct group than in the other two groups (all P < 0.05). Overall, Omicron infection showed fewer signs of pulmonary consolidation than other SARS-CoV-2 variant infections[ 23 ]. Consolidation shadows may result from vasculitis, hemorrhage, and peripheral serous exudation caused by high viral loads attacking blood vessels, secondary or direct alveolar inflammation, massive immune cell filling, and small airway mucus plugs.…”