In 34 states, the seven-day average of new cases is higher now than it was a month ago. Although the virus has waned in populous states including California and Florida, it is wreaking unprecedented havoc in the Midwest and making an incipient return in parts of the Northeast.

“The weather report is darkly cloudy with further storms on the horizon,” said William Schaffner, an infectious disease professor at Vanderbilt University in Nashville, Tennessee.

Medical professionals have long warned about a resurgence of the novel coronavirus as colder temperatures in North America drive people inside and many jurisdictions reopen schools. Knowing that, scientists have been racing to prepare a vaccine. But even if it is approved, it’s unlikely to reach most of the public for many months.

Meanwhile, most attention has turned to President Donald Trump, who remains hospitalized with the disease that has killed about 210,000 Americans so far.

‘Twindemic’ threat

Schaffner said the lack of adequate social distancing and masking in rural areas may combine with the coming cold weather and influenza, possibly resulting in a “twindemic” that further strains the health-care system.

In Nebraska, the seven-day average of cases hit a record Saturday, joining Midwestern and Western states including Wisconsin, Montana and the Dakotas in confronting a virus that had eluded them until recently. In New York City, schools in virus hot spots will close down Tuesday.

Across the country, there were 41,075 new cases reported on Sunday, bringing the total to 7,420,921, according to Johns Hopkins University.

“We’re in very bad shape, never having achieved any sense of containment, never gotten below 20,000 new confirmed cases per day,” said Eric Topol, director of Scripps Research Translational Institute. “Things can only get worse on this course.”