The director of the Facilities for Illness Management and Prevention issued a grave warning on Friday that a recent sharp drop in coronavirus cases across the United States “could also be stalling” and “leveling off at a really excessive quantity” — a worrisome growth that comes as more cases of concerning new variants have been found, and will counsel that a return to normalcy is not yet quite as near as many Individuals had hoped.

Even as the vaccination campaign continues, the director, Dr. Rochelle Walensky, additionally warned governors to not roll again mask mandates or other efforts to contain the virus: “Issues are tenuous. Now is just not the time to chill out restrictions.”

According to a New York Times database, virus instances throughout the US look like leveling off from the steep decline that started in January, with figures similar to these reported in late October. Circumstances have barely elevated week over week in current days, although extreme climate restricted testing and reporting in Texas and different states the earlier week, and never all states reported full knowledge on the Presidents Day vacation. The seven-day common of recent instances was 77,800 as of Thursday.

Whereas deaths are inclined to fluctuate greater than instances and hospital admissions, Dr. Walensky informed reporters throughout a White Home briefing on the pandemic, the newest seven-day common is barely increased than the typical earlier within the week. The seven-day common of newly reported deaths was 2,165, as of Thursday.

“We at C.D.C. contemplate this a really regarding shift within the trajectory,” she mentioned, including, “I wish to be clear: instances, hospital admissions and deaths — all stay very excessive and the current shift within the pandemic should be taken extraordinarily severely.”

Dr. Walensky mentioned a few of the rise could also be attributable to new variants of the coronavirus that unfold extra effectively and shortly. The so-called B.1.1.7 variant, which first emerged in Britain, now accounts for roughly 10 % of all instances in the US, up from one to 4 % a number of weeks in the past, she mentioned. The U.S. skill to trace variants is much less robust than Britain’s.

“I do know persons are drained; they wish to get again to life, to regular,” she mentioned. “However we’re not there but.”

As instances had declined, some governors around the United States have begun to relax pandemic restrictions. States with Republican governors seemed to be extra desirous to make rollbacks, although New York, which has a Democrat as governor, has also been easing restrictions on a variety of activities. On Thursday, Gov. Greg Abbott of Texas mentioned he was contemplating lifting a statewide masks mandate in place since July.

In Mississippi, Gov. Tate Reeves mentioned he was additionally contemplating pulling back some restrictions, significantly masks mandates for individuals who have been absolutely vaccinated. As of Thursday, simply over 12 % of the state’s inhabitants has acquired no less than one shot, and 5.5 % have acquired two, according to a Times database.

Dr. Anthony S. Fauci, the federal government’s high infectious illness knowledgeable, echoed Dr. Walensky’s warnings that extra rollbacks at state or native ranges can be unwise, noting that case ranges remained at a “very precarious place.”

“We don’t wish to be folks all the time wanting on the darkish aspect of issues, however you wish to be sensible,” he mentioned. “So we now have to rigorously have a look at what occurs over the subsequent week or so with these numbers earlier than you begin making the comprehensible must chill out on sure restrictions.”

The medical doctors’ feedback got here because the Biden administration introduced an aggressive push to enlist the assistance of a few of the nation’s greatest firms and enterprise lobbying teams, together with the U.S. Chamber of Commerce, the Enterprise Roundtable and organizations representing Asian, Black and Latino executives.

The intention is two-fold: to increase the non-public sector’s contributions past the manufacture of vaccines, checks and remedy, and to encourage companies to present staff break day and the required assist to get vaccinated, mentioned Andy Slavitt, a senior Biden well being adviser.

Mr. Slavitt ticked off an inventory of firms and teams which have responded to what he described because the administration’s “name to motion”: Ford and The Hole intend to donate greater than 100 million masks totally free distribution. Uber and Lyft are teaming up with pharmacies to supply free or discounted rides to vaccination sties. Greatest Purchase, Greenback Common and Goal will give staff paid break day to get a shot. He mentioned the initiatives can be coordinated by the businesses themselves and the administration didn’t have a proper function.

Professional sports activities leagues, Mr. Slavitt mentioned, are serving to put aside greater than 100 stadiums and arenas to turn out to be mass vaccination websites. A couple of weeks in the past, Mr. Biden introduced in a C.B.S. interview that the N.F.L. commissioner had supplied him using stadiums.

“We’ll ask firms to make related distinctive commitments that convey their distinctive abilities and assets to the issue of key maintaining Individuals protected and ending the pandemic as shortly as doable,” Mr. Slavitt mentioned.