Rendering of a coronavirus molecule suspended with others on a blue and purple background

The SARS-CoV-2 omicron variant is much less likely to cause severe illness and death than its predecessors, according to a new analysis by the Centers for Disease Control and Prevention.

CDC investigators examined data from three surveillance systems and a large healthcare database, looking at three high–COVID-19 transmission periods when the omicron, delta and earlier variants were dominant.

COVID-19 cases skyrocketed when the omicron variant emerged in the United States in December, the data showed. This has resulted in an unprecedented number of COVID-19-related emergency department visits and hospital admissions since the beginning of the pandemic. But the ratio of emergency department visits, hospitalizations and deaths to cases during the omicron period has been substantially lower than during the previous time periods.

What’s more, hospitalized patients have experienced less severe disease, with lower rates of ICU admissions, receipt of invasive mechanical ventilation, lengths of stay and in-hospital deaths, reported A. Danielle Iuliano, Ph.D., of the CDC’s COVID-19 Emergency Response Team, and colleagues.

“Concurrent increases in ED visits and hospital admissions appear to be driven by high case counts and not by increased disease severity following acute infection,” the authors concluded. 

These findings echo those from studies from other countries where omicron first was detected, as well as from health systems in California and Texas, they added.

Although the news is positive, the authors emphasized the need to continue practicing emergency preparedness measures.

“The high volume of hospitalizations resulting from high transmission rates during a short period can strain local health care systems in the United States, and the average daily number of deaths remains substantial,” they wrote.