Hospitals, facing staff shortages, are under enormous strain. In New York City, hospitalizations have exceeded the peak of last winter’s surge. And Governor Larry Hogan of Maryland declared a state of emergency on Tuesday, noting that the state had more hospitalized Covid-19 patients at that time than at any previous point during the pandemic.

“We’re in truly crushed mode,” said Dr. Gabe Kelen, director of the Johns Hopkins University School of Medicine’s emergency department.

The number of I.C.U. patients is a lagging indicator, likely to rise in the coming weeks, experts said. What’s more, some states are still struggling under the crush of hospitalizations from Delta, a previous version of the virus that may be more virulent. (Hospitals are frequently in the dark about which variant newly admitted patients are infected with.)

Still, several reports suggest that Omicron is a foe different from the variants that came before. And the challenges hospitals face — at least so far — are less about stockpiling equipment and more about staffing and contagion, doctors said.