The record came only a day after the Centers for Disease Control and Prevention reduced the number of days that infected Americans should remain isolated to five days from 10. The C.D.C. changed course as Omicron’s rapid spread has worsened a labor shortage, upending the hospitality, medical and travel industries, among others. The agency did not recommend rapid testing before people left isolation, and experts warned that that omission risked seeding new cases and heaping even more pressure on already overburdened health systems.
