They analyzed 69,279 symptomatic patients who tested positive for the coronavirus from Nov. 30 to Jan. 1. Three-quarters of the positive samples contained the Omicron variant, and the rest were Delta.

The researchers then followed the people who tested positive to see whether they ended up in the hospital. They excluded the so-called incidental Covid patients who showed up at hospitals for other complaints and tested positive for the coronavirus after arriving.

Compared with Delta, Omicron cut the risk of hospitalization in half, the study found, and the people who came to the hospital with Omicron stayed for a shorter period. The variant cut hospital stays by more than three days, a reduction of 70 percent compared with Delta.

Fourteen of the Delta-infected patients died, while only one Omicron patient did.