Risk of ICU Admission or Death 83 Percent Lower Among Omicron Compared to Delta COVID-19 Cases: Study

A study from Canada adds to the growing body of knowledge that suggest the Omicron COVID-19 variant is much less severe compared to the Delta variant—researchers found the risk of intensive care unit admission or death is 83 percent lower among cases of Omicron compared to Delta.

The study, published on medRxiv ahead of peer review and updated on Jan. 2, found the overall risk of hospitalization was 65 percent lower for Omicron compared to Delta.

“Our results align with findings from South Africa, Scotland, and England, all of which have demonstrated substantial decreases in risk of hospitalization associated with Omicron,” the authors wrote.

The Omicron COVID-19 strain “appears to demonstrate lower disease severity for both vaccinated and unvaccinated individuals,” but while this is the case, “the absolute number of hospitalizations and impact on the healthcare system is likely to be significant due to the large number of Omicron infections.”

Results are based on a matched cohort study with cases in Canada’s Ontario matched on gender, age, vaccination status, health region, and onset date. Of the 29,594 Omicron cases that were eligible for the study, researchers were able to match 11,622 cases with at least one Delta case.

Among the matched Omicron cases, there were 59 (0.51 percent) hospitalizations and three (0.03 percent) deaths; among the matched Delta cases, there were 221 (1.6 percent) hospitalizations and 17 (0.12 percent) deaths.

“Our study has some limitations, in particular the short follow-up duration and potential misclassification due to incidental findings from hospital admission screening, and incomplete public health follow-up as incidence increased,” authors said.

A South African study published Dec. 28 showed that the latest COVID-19 wave, with presumed majority of admissions to be the Omicron strain had a 4.5 percent hospital death rate, compared to 21.3 percent in other strains. ICU admissions were 1 percent compared to 4.3 percent for previous waves. Less than half—about 45 percent—of hospital admissions required supplemental oxygen, compared to 99.5 percent in the first wave of COVID-19.

A recent analysis from the United Kingdom released Dec. 23 showed the risk of hospitalization with Omicron is up to 70 percent less compared to Delta. A study in Scotland, published Dec. 22, found a two-thirds risk reduction of COVID-19 hospitalization in Omciron compared to Delta.

The head of the U.S. Centers for Disease Control and Prevention (CDC), Dr. Rochelle Walensky, said in late December 2021 the Omicron variant accounts for more than 90 percent of COVID-19 cases in some parts of the United States.