Across the US, coronavirus outbreaks seem to be larger than ever before.

On Saturday, 12 states hit record seven-day rolling average case counts, according to a Business Insider analysis of data from The COVID Tracking Project, which compiles data from state and territory-level public health authorities.

Alaska, Colorado, Indiana, Kansas, Minnesota, Missouri, Montana, North Dakota, Nebraska, Oregon, South Dakota, and Utah recorded more new infections in the last seven days than they ever have in a one-week period.

The US overall has recorded more than 50,000 new cases each day for the last four days. The country hasn't seen such a streak since mid-August.

Case counts are high - with a seven-day daily average of at least 15 new cases per 100,000 people - in 26 states, according to analysis from The New York Times. Daily case counts are growing in another 16 states and Washington, DC.

"We are all seeing increasing numbers of COVID-19 patients who are coming into our ERs, who are getting really sick, requiring hospitalisation and even intensive care," Megan Ranney, an emergency-room physician and Brown University associate professor, told CNN on Sunday.

"We are all deeply afraid that this is the beginning of that dreaded second wave."

Experts have long warned that the coronavirus could make a fall resurgence, as children and college students return to classrooms and cooler weather sends people indoors.

Dr. Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases and the nation's top infectious-disease expert, has said that Americans need to "hunker down and get through this fall and winter."

"As we get into the fall and we do more indoor things, we are likely to see upticks in COVID-19," Fauci said in a September panel discussion with Harvard Medical School.

Daily death counts are still trending downward. But deaths usually lag behind case counts by three to four weeks as it takes time to die of a coronavirus infection.

An influential COVID-19 model, from the Institute for Health Metrics and Evaluation at the University of Washington School of Medicine, is now projecting that deaths will peak at about 2,300 per day in mid-January and that the total death toll will nearly double to 400,000 by February.

If 95 percent of the population wore masks in public, the IHME model projects, the death toll would be about 315,000 my February. Currently, less than 70 percent of people surveyed have said they do so.

This article was originally published by Business Insider.

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