Scarcely two months after the Omicron variant drove coronavirus case numbers to frightening heights in the United States, scientists and health officials are bracing for another swell in the pandemic and, with it, the first major test of the country’s strategy of living with the virus while limiting its impact.

At local, state and federal levels, the nation has been relaxing restrictions and trying to restore a semblance of normalcy. Encouraging Americans to return to prepandemic routines, officials are lifting mask and vaccine mandates and showing no inclination of closing down offices, restaurants or theaters.