Comparative Evaluation of the Clinical Severity of COVID-19 Produced by the Omicron Variant Versus the Wuhan Strain

Purpose: Starting from the observations of the in vitro studies that describe a lower pathogenicity of the Omicron variant, we proposed to comparatively analyze two groups of patients admitted to our clinic, one at the beginning of the COVID-19 pandemic, and the other one at the beginning of the Omicron wave of the pandemic, and to compare the severity of disease episodes.

Patients and methods: 2 groups of patients with COVID-19, one group of 480 patients hospitalized in our clinic in March-August 2020 and one group of 320 patients admitted in January-June 2022, were selected. Demographic data, paraclinical profile at admission, comorbidities, the type and duration of treatment and the evolution of the patients in the two groups, were analyzed comparatively.

Results: Our study showed statistically significant differences between group A compared to the group B, which support the aggressiveness of the Wuhan strain and the severity of its disease forms, such as: the predominance of pulmonary opacity on radiographies, a higher need for immunosuppressive therapies, a lower oxygen saturation, and a higher average values of inflammatory markers at admission, in the first group. Also, some factors with predictive potential for a severe clinical form, with predominance in group 2 (older age, a higher score of cumulative comorbidities, a higher value of D-dimers and aspartateaminotransferase, a lower value of concentration of prothrombin, and the higher average CURB-65 score, at admission) were observed.

Conclusion: Our study identified predictive parameters of severity (D-dimers, aspartate-aminotransferase, prothrombin concentration, CURB-65 Score), statistically significant modified in the Omicron wave group compared to the Wuhan wave group, which draw attention to the possibility of severe and unfavorable evolution of the infection with Omicron in elderly population with multiple comorbidities.