91% reduction in risk of death with Omicron compared to Delta, CDC-funded study shows

Omicron infections are associated with a 91% reduction in risk of death compared to the Delta variant, CDC Director Rochelle Walensky said on Wednesday (Jan. 12), citing a new Kaiser Permanente Southern California study that looked at 52,297 Omicron cases and 16,982 Delta cases in California between November 30 and January 1.

The study, which is yet to be peer reviewed, also showed that Omicron infections were also associated with a 74% reduction in risk of going to the ICU, as well as a 53% reduction in risk of being hospitalized, Walensky said. No patients with Omicron required mechanical ventilation.

Additionally, those with Omicron had a shorter duration in hospital stay compared to Delta patients: “The duration of hospital stays was approximately 70% shorter, with the median of stays being 1.5 days for Omicron, compared to about five days for Delta,” Walensky said.

“Looking at all hospital admissions for Omicron, 90% of patients were expected to be discharged from the hospital in three days or less,” she added.

⬇️53% less risk of symptomatic hospitalization
⬇️74% less risk of ICU admission
⬇️91% less risk of death
0️⃣Omicron patients required mechanical ventilation

The study was done with CDC collaboration and funding.