Omicron variant less severe, with patients 91% less likely to die than from delta version: CDC

The COVID-19 variant omicron is milder than delta, as infected people are 91% less likely to die and no one has been recorded as requiring mechanical ventilation, according to a new study funded by the Centers for Disease Control and Prevention (CDC).

"During a period with mixed Delta and Omicron variant circulation, SARS-CoV-2 infections with presumed Omicron variant infection were associated with substantially reduced risk of severe clinical endpoints and shorter durations of hospital stay," the authors of the preprint study wrote.

The CDC's Director Rochelle Walensky tweeted a link to the study with an image of three graphs showing how compared to delta, patients with omicron have 53% less likely to have symptomatic hospitalization, 74% likely to be admitted to the ICU and 91% less likely to die.

"While less severe, #Omicron is much more transmissible & we are seeing the unprecedented impact," Walensky added in a follow-up tweet. "Over 1M cases in a day, 99% of counties with high transmission & strained healthcare systems."

More than 52,000 omicron cases and nearly 17,000 delta cases were analyzed in the Kaiser Permanente Southern California healthcare system from Nov. 30, 2021, to Jan. 1, 2022.

Even though more than three times the number of omicron cases were studied than delta, "Hospital admissions occurred among 235 (0.5%) and 222 (1.3%) of cases with Omicron and Delta variant infections, respectively," the researchers wrote.

While omicron is less severe regardless of vaccination status or prior infection, researchers found evidence that vaccination reduces the severity of infection for both variants, so continuing to encourage COVID-19 vaccines would create "substantial public health benefits."

More than 12.3 million COVID cases have been recorded in the United States over the past month.