COVID-19 Variants in Critically Ill Patients: A Comparison of the Delta and Omicron Variant Profiles

Abstract

Background: Coronavirus disease is a pandemic that has disrupted many human lives, threatening people’s physical and mental health. Each pandemic wave struck in different ways, infectiveness-wise and mortality-wise. This investigation focuses on critically ill patients affected by the last two variants, Delta and Omicron, and aims to analyse if any difference exists between the two groups. Methods: intensive care unit (ICU) COVID-19 consecutive admissions between 1 October 2021 and 31 March 2022 were recorded daily, and data concerning the patients’ demographics, variants, main comorbidities, ICU parameters on admission, and the outcome were analysed by a univariate procedure and by a multivariate analysis. Results: 65 patients were enrolled, 31 (47.69%) belonging to the Omicron versus 34 (52.31%) to the Delta group. The mortality rate was 52.94% for the Omicron group versus 41.9% for the Delta group. A univariate analysis showed that the Omicron variant was associated with total comorbidities number, Charlson Comorbidity Index (CCI), pre-existing pulmonary disease, vaccination status, and acute kidney injury (AKI). In stepwise multivariate analysis, the total number of comorbidities was positively associated with the Omicron group, while pulmonary embolism was negatively correlated with the Omicron group. Conclusion: Omicron appears to have lost some of the hallmarks of the Delta variant, such as endothelialitis and more limited cellular tropism when it comes to the patients in the ICU. Further studies are encouraged to explore different therapeutic approaches to treat critical patients with COVID-19.

The central role of the gut in intensive care

“…The SARS-CoV-2 pandemic has impacted every field of medicine, including intensive care, where each virus variant has differently affected critically ill patients [ 162 ]. The role of probiotics in infected patients in intensive wards has not been systematically explored.…”

Endothelial Dysfunction in COVID-19: Potential Mechanisms and Possible Therapeutic Options

“…This discovery could, therefore, explain both the reduced incidence of pulmonary embolism associated with this variant [ 72 ] and the need to adapt prophylactic therapy with heparin, thus balancing both thrombotic and hemorrhagic risk. In a prospective study conducted on critically ill patients admitted because of COVID-19, Omicron patients had a lower incidence of pulmonary embolism than Delta ones [ 73 ]. Finally, Corriero et al reported that vaccines determine better protection in Omicron patients than Delta ones, and three vaccine doses increase protection in Omicron patients up to 60–75% [ 73 ].…”

“…In a prospective study conducted on critically ill patients admitted because of COVID-19, Omicron patients had a lower incidence of pulmonary embolism than Delta ones [ 73 ]. Finally, Corriero et al reported that vaccines determine better protection in Omicron patients than Delta ones, and three vaccine doses increase protection in Omicron patients up to 60–75% [ 73 ].…”

Update on Innate Immunity in Acute Kidney Injury—Lessons Taken from COVID-19

“…There is, in fact, only one publication analyzing the Delta–Omicron disparities concerning AKI in critically ill patients. Of note, the results have to be interpreted cautiously because of the small study group [ 69 ]. The comparison of 31 Omicron patients and 34 Delta patients revealed higher mortality rates and numbers of pre-existing comorbidities, as well as more frequent AKI incidence, in those who suffered from Omicron variant infection.…”

“…The paradox of higher AKI prevalence in Omicron vs. Delta patients may result from faster virus replication for the price of less specialized cell tropism, priming the spreading of infection in the population over preference to specific organs [ 69 ]. Such low specialization with ubiquitous access would also add to the overall severe clinical status of Omicron patients in the ICU.…”