Covid-19 cases are starting to climb again in select regions across the U.S. after stabilizing at a high level following this summer’s delta surge, White House chief medical advisor Dr. Anthony Fauci said Monday.

Fauci’s comments came just a day after the country reported a seven-day average of more than 82,000 new cases, up 11% from the week before, according to a CNBC analysis of data from Johns Hopkins University. Nationwide cases were down 57% last week from the delta wave’s peak this summer, but an influx of Covid patients in the Midwest and Northeast are fueling the sudden increase.

“The only thing that’s a little bit disconcerting is that we’re beginning to plateau,” Fauci said during an interview hosted by the Bipartisan Policy Center. “In other words, the deceleration of cases is now plateaued, and in some areas of the country, we’re starting to see a bit of an uptick.”  

Infections had been on the decline for weeks after hitting a delta-wave peak of 172,500 new cases per day on Sept. 13. They flattened out at a high level, bouncing between 70,000 and 75,000 new cases a day for nearly three weeks through most of last week, and are now once again increasing. 

Average daily cases have jumped by 19% and 37% in the Midwest and Northeast over the last week, respectively, according to Hopkins data. Hospitalizations, which lag an increase in infections, are up 11% over that same period in the Midwest, while the number of currently hospitalized patients with Covid is flat in the Northeast.

Cases and hospitalizations have fallen sharply in the South, where the delta wave hit earliest and hardest over the summer.

About 47,000 patients with the virus are currently hospitalized nationwide, according to a seven-day average of data from the Department of Health and Human Services, and the U.S. is reporting an average of roughly 1,150 Covid fatalities per day, according to Hopkins data. Both figures are flat over the past week.

Besides the plateauing cases, Fauci said the U.S. must focus on vaccinating the roughly 60 million people nationwide who have not yet been immunized. That excludes 28 million children ages 5 to 11 who became eligible to receive Pfizer’s two-dose Covid vaccine earlier this month, he noted.

“There’s a lot of good news, but some challenging news that we really need to address as we go into the winter months,” Fauci said.

Fauci added that those who’ve been fully vaccinated for Covid can gather for the holiday season without concern. But he recommended wearing a mask in indoor congregate settings with cases still hovering at a high level nationwide.

“When you’re with your family at home, goodness, enjoy it with your parents, your children, your grandparents,” he said. “There’s no reason not to do that.”