The U.S., which last week had its highest single-day case counts since the pandemic began, led the world with 10 million cases and more than 239,000 deaths, NBC News data show.
States across the U.S. were adding thousands of new cases daily, with Illinois recording a national high of more than 12,000 on Saturday, according to the data.
Illinois Gov. J.B. Pritzker self-isolated last week after he met with someone who tested positive for the virus. Pritzker and other staff members tested negative Saturday, The Associated Press reported.
Public health experts have warned that the country could record more than 2,000 deaths a day by January — and that the virus will continue to surge during the winter, when families spend more time indoors and around people outside their immediate circles during the holidays.
Experts also worry about the possibility of a "twindemic," with rising cases of Covid-19 and the seasonal flu overwhelming hospitals.
"We need to sacrifice a little now to get back to what we used to be able to do in the future," said Dr. Ken Lyn-Kew, a critical care pulmonologist at National Jewish Health, a hospital in Denver. "If we don't, a lot of our loved ones aren't going to be there when we get back together again."
European countries were also struggling with a resurgent virus, with leaders in Germany, France, the U.K. and elsewhere imposing new restrictions.
In China, where the pandemic began, the virus appears to be under control: No new deaths have been reported since April, although NBC News has not independently confirmed the National Health Commission's data.
While China has been criticized for silencing whistleblowers and minimizing the virus's severity early in the pandemic, experts have said the country has done a good job of blunting its spread through restrictions that would not be tolerated in a country like the U.S.