Ten states reported their highest single-day tallies of new Covid-19 infections Friday, and the country reported its highest one-day total since July, as experts say a dangerous fall surge of coronavirus infections is well underway.
"This really is a harrowing time, and people have to be careful," epidemiologist Dr. Abdul El-Sayed told CNN on Saturday.
"When we saw this kind of transmission earlier in the pandemic, in March and April, the virus hadn't seeded everywhere ... This surge has the potential to be way worse than it was than either the spring or the summer," El-Sayed, Detroit's former health director, said.
The US reported more than 69,100 new Covid-19 infections Friday -- the most in a single day since about 71,300 were reported July 29, according to Johns Hopkins University data.
Ten states Friday reported their highest one-day case counts: Colorado, Idaho, Indiana, Minnesota, New Mexico, North Carolina, North Dakota, West Virginia, Wisconsin and Wyoming, according to Johns Hopkins.
As for the entire country, cases are swinging up after a summer surge waned.
Daily US case averages had dipped to around 34,300 by September 12. But now, the country is averaging more than 55,000 new cases daily over the past week -- up more than 60% since mid-September's dip.
Covid-19 hospitalizations also are climbing nationwide. And they'll likely be followed by a rise in daily coronavirus deaths, says Dr. Francis Collins, director of the National Institutes of Health.
"This is a good moment for people to stop and ask themselves, 'What can I do to try to be sure that we limit the further infections that otherwise seem to be looming in front of us as cold weather is kicking in and people are indoors, and those curves are going upward, in the wrong direction?' " Collins said Friday.
New Mexico Gov. Michelle Lujan Grisham said hospitalizations in her state have increased 101% this month.
"Every New Mexican can and must do their part to stop the spread of COVID-19 by staying home, limiting their interactions with others, and wearing their masks," she tweeted.
The country recently has averaged about 700 Covid-19 deaths a day, below the daily tolls above 1,000 from late July to mid-August.
But University of Washington researchers project more than 2,300 Americans could die daily by mid-January, and a total of more than 389,000 people could die from the virus in the US by February 1.
'We are in a new wave of rising positivity in Covid-19 cases'
Experts say Americans can help get the virus under control by heeding guidelines touted by officials for months: avoiding crowded settings, keeping a distance, keeping small gatherings outdoors, and wearing a mask.
The upticks have prompted state leaders to push new measures, like mask enforcements and gathering limits, in hopes of curbing the spread.
Nebraska Gov. Pete Ricketts announced changes to the state's health measures, including requiring hospitals to reserve at least 10% of staffed general and ICU beds for Covid-19 patients.
In New Mexico, the governor this week ordered new mass gathering limitations and a 10 p.m. closing time for establishments serving alcohol. And in Kentucky, Gov. Andy Beshear said this month he instructed authorities to step up mask enforcement.
US Surgeon General Dr. Jerome Adams addressed a surge of new cases and hospitalizations in Wisconsin and said the state's test-positivity rates are "going in the wrong direction."
"It is critical that we actually understand where this virus is circulating so that we could get cases under control and reverse positivity," he said Friday in Neenah, Wisconsin, while announcing a new testing location there.
Minnesota outbreak tied to Trump rally
In Minnesota, public health officials say they've so far traced at least 20 cases of the virus back to a rally held by President Donald Trump last month, or to related events.
Of the 20 cases,16 are among people who attended the rally. Four people said they participated in counter-protests the same day, the state's health department told CNN.
The state has traced a total of 28 cases to various campaign events in recent weeks. One was linked to a rally for Democratic presidential candidate Joe Biden and three were linked to a Minneapolis speech by Vice President Mike Pence in late September.
Trump attended a rally in Muskegon, Michigan, on Saturday, a day after the state reported it's highest number of new cases in a day.
Michigan Gov. Gretchen Whitmer has encouraged people who were planning to attend to wear masks and social distance. Hours before the rally, health officials reported 1,791 new Covid-19 cases in a day.
And in Tucson, Arizona, where Trump is scheduled to hold a political rally Monday, the mayor wrote an open letter to remind campaign officials of the "various ordinances in effect" in the city and county.
"It would be deeply unfortunate if one gathering jeopardized all the progress we have made thus far," Mayor Regina Romero wrote.
Pfizer announces Covid-19 vaccine plans
In an open letter published Friday by Pfizer Chairman and CEO Albert Bourla, the company said it plans to apply for emergency use authorization for its Covid-19 vaccine as early as November.
"Assuming positive data, Pfizer will apply for Emergency Authorization Use in the US soon after the safety milestone is achieved in the third week of November," the letter said.
But first, Bourla wrote, the vaccine should prove to be safe and effective in preventing the disease.
"And finally, we must demonstrate that the vaccine can be consistently manufactured at the highest quality standards," Bourla wrote.
Once a vaccine is approved in the US, CVS and Walgreens pharmacies have been designated to help distribute free vaccines to long-term care facilities, federal officials confirmed. It will be up to the two drug chains to figure out how to deliver the vaccines, including cold storage requirements and personal protective equipment.
"This is a completely voluntary program on the part of every nursing home. This is an opt-in program," Paul Mango, deputy chief of staff for policy at the Health and Human Services Department, told reporters.
CNN's Jason Hanna, Dave Alsup, Chuck Johnston, Andrea Diaz, Nakia McNabb, Samira Said, Nadia Kounang, Andy Rose and Shelby Lin Erdman contributed to this report.