Omicron causing less severe illness in Southern California patients, study suggests

 A outdoor sign that says "Welcome. Kaiser Permanente, Los Angeles Medical Center."
Kaiser Permanente in Los Angeles.
(Irfan Khan / Los Angeles Times)
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New data from Southern California are providing further evidence that the Omicron variant of the coronavirus is causing less severe illness than its Delta cousin, the culprit behind last summer’s wave.

A preliminary study based on medical records from nearly 70,000 Kaiser Permanente Southern California patients “noted substantially reduced risk of severe clinical outcomes in patients who are infected with the Omicron variant compared with Delta,” said Dr. Rochelle Walensky, director of the U.S. Centers for Disease Control and Prevention.

The study — which included more than 52,000 Omicron cases and nearly 17,000 Delta cases within the Kaiser system from Nov. 30 to Jan. 1 — found that, compared with patients infected with Delta, those who had Omicron were 53% less likely to be hospitalized with COVID-19, 74% less likely to be admitted to the intensive care unit, and 91% less likely to die of the disease.


Among patients who were hospitalized, the median length of stay was 1.5 days for patients infected with Omicron and five days for those who had Delta.

Another sign of Omicron’s lighter touch: None of the patients who had it required mechanical ventilation.

The findings were posted Tuesday on MedRxiv, a website on which researchers share preliminary results. The study has not been reviewed by independent scientists.

“The data in this study remain consistent with what we are seeing from Omicron in other countries, including South Africa and the U.K., and provide some understanding of what we can expect over the coming weeks as cases are predicted to peak in this country,” Walensky said during a briefing Wednesday.

Scientists are seeing signals that the wave may have peaked in Britain and is about to do the same in the U.S.

Jan. 11, 2022

The new study is the latest to indicate Omicron is milder, on the whole, compared with Delta. Still, the variant is spreading widely and hospitals are seeing an influx of coronavirus-positive patients.

Omicron is the dominant coronavirus strain in the U.S., accounting for an estimated 98% of new cases nationwide, according to the CDC.

Los Angeles County’s hospitals are straining to provide medical care, hobbled by staffing shortages far worse than last winter’s coronavirus surge.


Many healthcare workers, burned out by the pandemic, have quit, and many who remain have tested positive for the virus and are at home isolating. And healthcare facilities are busier this year because there’s more demand for non-COVID-19 care.

Experts say it’s a necessary solution to staffing shortages, yet many workers say the policy could be dangerous.

Jan. 12, 2022

In the face of the latest surge in cases, Kaiser Permanente Southern California is temporarily postponing all elective surgeries that require a stay in the hospital, it announced Wednesday.

The hospital system will continue to perform emergency surgeries, urgent procedures including those involving cancer patients or people whose medical condition would be worsened by a delay, and elective outpatient surgeries that do not require an overnight stay in the hospital, its regional director of medical quality, Dr. Nancy Gin, said.

“We will continue to do everything we can to minimize the impact on our members and the public,” Gin said.