NEW YORK (AP) — U.S. health officials on Monday cut isolation restrictions for asymptomatic Americans who catch the coronavirus from 10 to five days, and similarly shortened the time that close contacts need to quarantine.

Centers for Disease Control and Prevention officials said the guidance is in keeping with growing evidence that people with the coronavirus are most infectious in the two days before and three days after symptoms develop.

The decision also was driven by a recent surge in COVID-19 cases, propelled by the omicron variant.

Early research suggests omicron may cause milder illnesses than earlier versions of the coronavirus. But the sheer number of people becoming infected — and therefore having to isolate or quarantine — threatens to crush the ability of hospitals, airlines and other businesses to stay open, experts say.

CDC Director Rochelle Walensky said the country is about to see a lot of omicron cases.

“Not all of those cases are going to be severe. In fact many are going to be asymptomatic,” she told The Associated Press on Monday. “We want to make sure there is a mechanism by which we can safely continue to keep society functioning while following the science.”

Last week, the agency loosened rules that previously called on health care workers to stay out of work for 10 days if they test positive.