CDC study: Omicron appears to cause less severe disease

The omicron variant is on average causing less severe disease than previous variants of the virus, a new Centers for Disease Control and Prevention (CDC) study found.

The ratio of hospital admissions to cases and the ratio of deaths to cases were lower during the omicron wave than during the delta variant peak last year or the winter of 2020-2021, the study found.

Still, omicron is placing a strain on hospitals, the study said, even if a smaller percentage of cases are severe.

“Despite Omicron seeing the highest reported numbers of COVID-19 cases and hospitalizations during the pandemic, disease severity indicators, including length of stay, ICU admission, and death, were lower than during previous pandemic peaks,” the study stated.

“Although disease severity appears lower with the Omicron variant, the high volume of hospitalizations can strain local health care systems and the average daily number of deaths remains substantial,” it added.

The omicron variant caused 27 hospital admissions per 1,000 cases, the study found, lower than 68 per 1,000 cases in the winter of 2020-2021 or 78 per 1,000 during the delta wave. 

Similarly, the nine deaths per 1,000 cases during omicron was less than the 16 per 1,000 cases last winter or the 13 per 1,000 during the delta surge.

The study attributes omicron’s decreased severity to a mix of increased immunity from higher rates of vaccination and previous infection than during previous surges as well as the fact that the omicron variant inherently causes less severe illness.

While less severe, the omicron variant has still done plenty of damage. Hospitalizations set a record during the omicron surge, at more than 150,000, according to a New York Times tracker.

Deaths have not yet reached the record levels of last winter, before vaccines were widely available, but there are still more than 2,000 people dying every day from the virus, according to the Times tracker.