News Scan for Feb 18, 2022

Risk of severe disease much lower with Omicron COVID variant than DeltaThe risk of hospitalization, intensive care unit (ICU) admission, and death was much lower among more than 9,000 Canadian COVID-19 patients infected with the Omicron variant than among matched Delta patients, according to a study published yesterday in JAMA.The risk of hospitalization or death with Omicron was 41% of—and the risk of death was one-tenth of—that of Delta.Public Health Ontario researchers retrospectively studied the outcomes of all COVID-19 patients in the province with illness onset from Nov 22 to Dec 24, 2021, amid the Omicron surge but before the emergence of the Omicron BA.2 subvariant.

Median follow-up was 24 days.Omicron cases were identified using whole-genome sequencing or S gene target failure testing, and Delta cases were identified through these methods or as those not identified as Omicron.Among 37,296 Omicron cases, 9,087 were matched in a 1:1 ratio with Delta cases.

Fifty-three Omicron patients (0.6%) were hospitalized, and 3 (0.3%) died, compared with 129 hospitalizations (1.4%) and 26 deaths (0.3%) among Delta patients.The hazard ratio (HR) for hospitalization or death among Omicron patients relative to Delta patients was 0.41 (95% confidence interval [CI], 0.30 to 0.55) (0.33 in a sensitivity analysis [95% CI, 0.19 to 0.56]).

The HR for ICU admission or death was 0.19 (95% CI, 0.09 to 0.39), while it was 0.12 (95% CI, 0.04 to 0.37) for death.Estimates of Omicron severity stratified by age, sex, and vaccination status all indicated decreased severity."The results align with findings from South Africa, Scotland, and England, all of which have demonstrated substantial decreases in risk associated with Omicron," the