Comparison of the clinical characteristics of SARS-CoV-2 Delta (B.1.617.2) and Omicron (B.1.1.529) infected patients from a single hospitalist service

Abstract

Background While existing evidence suggests less severe clinical manifestations and lower mortality are associated with the Omicron variant as compared to the Delta variant. However, these studies fail to control for differences in health systems facilities and providers. By comparing patients hospitalized on a single medical service during the Delta and Omicron surges we were able to conduct a more accurate comparison of the two varaints’ clinical manifestations and outcomes. Methods We conducted a prospective study of 364 Omicron (BA.1) infected patients on a single hospitalist service and compared these findings to a retrospective analysis of 241 Delta variant infected patients managed on the same service. We examined differences in symptoms, laboratory measures, and clinical severity between the two variants and assessed potential risk drivers for case mortality. Findings Patients infected with Omicron were older and had more underlying medical conditions increasing their risk of death. Although they were less severely ill and required less supplemental oxygen and dexamethasone, in-hospital mortality was similar to Delta cases, 7.14% vs. 4.98% for Delta (q-value = 0.38). Patients older than 60 years or with immunocompromised conditions had much higher risk of death during hospitalization, with estimated odds ratios of 17.46 (95% CI: 5.05, 110.51) and 2.80 (1.03, 7.08) respectively. Neither vaccine history nor variant type played a significant role in case fatality. The Rothman score, NEWS-2 score, level of neutrophils, level of care, age, and creatinine level at admission were highly predictive of in-hospital death. Interpretation In hospitalized patients, the Omicron variant is less virulent than the Delta variant but is associated with a comparable mortality. Clinical and laboratory features at admission are informative about the risk of death.

Genetic features of SARS-CoV-2 Alpha, Delta, and Omicron variants and their association with the clinical severity of COVID-19 in Vietnam

“…Hu et al [29] reported that older age was an independent factor in severe and fatal cases. Radhakrishnan et al [30] found that infection with the Delta variant resulted in a higher mortality rate than infection with other variants. Therefore, developing a clinical model to predict outcome in patients with COVID-19, particularly, with severe and critical clinical circumstances, is crucial.…”

Viral infections causing asthma exacerbations in the age of biologics and the COVID-19 pandemic

“…As the SARS-CoV-2 virus spread and vaccines became available worldwide, individuals developed natural and/or vaccination-induced immunity. This increasing immunity along with viral evolution that allowed for more transmissible but less virulent variants to emerge (i.e., variants from the Omicron lineage) were associated with a decreased COVID-19 disease severity [ 27 – 29 ]. As a result, many precautionary measures were lifted, allowing for a rapid resurgence of other viral illnesses, including RSV, rhinovirus, and influenza virus.…”

The Role of Neutrophil in COVID-19 — Positive or Negative

“…In severe mice, researchers found significantly increased CXCL1/2 levels, and the mice had even more recruited neutrophils in their lungs than ancestral strain-infected mice [88]. The NLR of patients infected with Delta variant is significantly increased in severe COVID-19, but it did not differ much from the NLR of severe Omicron patients [89, 90]. At present, there is paper that summarizes the effects of two consecutive amino acid mutations R203K and G204R (KR) in nucleocapsid (N) protein on patients and cellular immune responses [91].…”