4 Pence Aides Test Positive

Reports of new infections poured in at alarming levels on Saturday as the coronavirus continued to tear through the United States. Six states reported their highest-ever infection totals and more than 78,000 new cases had been announced by evening, one day after the country shattered its single-day record with more than 85,000 new cases.

The country’s case total on Saturday was the second highest in a single day. Case numbers on weekends are often lower because some states and counties do not report new data, so the high numbers on Saturday gave reason for alarm.

“This is exploding all over the country,” said Gov. Andy Beshear of Kentucky, whose state is among 17 that have added more cases in the past week than in any other seven-day stretch. “We’ve got to tamp down these cases. The more cases, the more people that end up in the hospital and the more people die.”

Officials in Alaska, Ohio, Oklahoma, Colorado, New Mexico and Illinois announced more new cases on Saturday than on any other day of the pandemic. The country as a whole has averaged more than 68,000 new cases per day over the last week, its highest seven-day average of the pandemic.

Rural areas and small metropolitan regions have seen some of the worst outbreaks in recent weeks, but by Saturday, many large cities were struggling as well.

The counties that include Chicago, Oklahoma City, Minneapolis, Anchorage and El Paso all set single-day records for new infections on Saturday. Across the country, hospitalizations have grown by about 40 percent since last month, and they continued to rise on Saturday. Around Chicago, where new restrictions on bars and other businesses took effect Friday, more than twice as many cases are now being identified each day than at the start of October.

“This moment is a critical inflection point for Chicago,” Mayor Lori Lightfoot has said.

States in the Midwest and Mountain West have been reporting some of the country’s most discouraging statistics, but worrisome upticks are occurring all over. New cases have emerged at or near record levels recently in Pennsylvania, Tennessee, Arkansas and New Mexico.

“Over the next week, two weeks, three weeks, please be extremely conservative in deciding how much time to spend outside of the home,” Gov. Michelle Lujan Grisham of New Mexico said Friday as she imposed new restrictions on businesses. “The visit to friends can wait — it’s not worth your life, or theirs.”

Experts worry that the growing numbers in need of hospital care will only get worse if cases continue to mount, especially in rural areas where medical facilities could be quickly overwhelmed.

The high case count in part reflects increased testing. With about one million people tested on many days, the country is getting a far more accurate picture of how widely the virus has spread than it did in the spring.

But public health officials warn that Americans are heading into a dangerous phase, as cooler weather forces people indoors, where the virus spreads easily. It could make for a grueling winter that tests the discipline of the many people who have grown weary of masks and of turning down invitations to see family and friends.

Dr. Anthony S. Fauci, the nation’s top infectious disease expert, said on Friday that the country should consider implementing a first-ever national mandate requiring masks, to help control a surge in coronavirus cases across the United States that has become the most severe to date.

Appearing on CNN, Dr. Fauci said that enforcing such a mandate would be difficult. But with conditions worsening across disparate regions of the country, he said he could be inclined to recommend the dramatic measure.

“There’s going to be a difficulty enforcing it,” he said, “but if everyone agrees that this is something that’s important and they mandate it and everybody pulls together and say, you know, we’re going to mandate it but let’s just do it, I think that would be a great idea to have everybody do it uniformly.”

Most states have imposed mask requirements to varying degrees, covering different spheres — such as indoor and outdoor spaces — at some point during the pandemic.

However, a minority of states, including Iowa, have resisted issuing directives on masks even as case counts have begun to climb to new highs. And even states and cities that have more restrictive orders in place tend to allow some exceptions, such as when people are exercising.

The White House has obstructed federal efforts that would have mandated masks in a more limited way, blocking an order drafted by the Centers for Disease Control and Prevention last month that would have required masks on public transportation.

But with more than a dozen states reporting more cases over the past week than in any other seven-day stretch during the pandemic, Dr. Fauci said that it may be necessary to have a more coordinated, national approach.

“I get the argument saying, ‘Well if you mandate a mask, then you’re going to have to enforce it and that’ll create more of a problem,’” he said. “Well, if people are not wearing masks then maybe we should be mandating it.”

Even as cases have risen to their highest levels yet in the United States, the White House Coronavirus Task Force has been meeting less frequently, Dr. Fauci said on Friday, appearing on MSNBC.

Recently, the group has been meeting weekly — less frequent than the sometimes daily meetings during the early spring, he said.

The last time that President Trump was at one of the White House coronavirus task force meetings, which are now virtual, was “several months ago,” Dr. Fauci said, adding: “Direct involvement with the president in discussions — I have not done that in a while.”

Vice President Mike Pence leads the task force, and relays guidance from the group’s medical experts to the president, Dr. Fauci said.

U.S. Roundup

More than 800 North Dakotans who tested positive for the coronavirus have been belatedly notified after the state health department faced a backlog of cases, health officials said this week.

The backlog was caused by the sharp increase in cases in the state, the health department said in a statement. Members of the North Dakota National Guard who had been helping the state’s contact tracing efforts since early last month were reassigned to notify the people who tested positive, a health department spokeswoman said.

With 5,422 new cases in the state over the past week — 711 cases per 100,000 people — the state has the highest levels of infection per person in the country, according to a New York Times database. New York State had 55 cases per 100,000 people over the past week.

To address the backlog, contact tracers began calling people who tested positive, rather than their normal duties of calling those positive cases’ close contacts.

People who came in close contact with someone who tested positive “will no longer be contacted by public health officials,” the department said, except for people in health care, K-12 schools and universities.

Instead, people who test positive will be asked to “self-notify their close contacts.”

In other developments around the country:

• Governor Greg Abbott of Texas asked the U.S. Health and Human Services Department on Saturday to authorize the use of an Army medical center on Fort Bliss for non-coronavirus patients in an effort to create more space at hospitals in the El Paso area for coronavirus patients.

• A state of emergency issued in March by Governor Kevin Stitt of Oklahoma was extended this week for another 30 days as the state faces record infection levels. As positive cases hit a new peak in the state, there have been an average of 1,221 new cases per day over the past week, an increase of 14 percent from the average two weeks earlier.

Warning signs flashed on Saturday that the pandemic has entered a dangerous phase across Europe, with several countries shattering daily infection records and uncertainty mounting about how the continent will battle its worst outbreak to date.

Deaths from the coronavirus in Germany surpassed 10,000 on Saturday, a disconcerting milestone in a country that has been widely admired for its ability to manage the pandemic. The number of new infections in a 24-hour period also reached a record level — 14,714 — although the country’s public health authority said that some of those cases should have been factored in earlier in the week but had not been because of technical issues.

Officials in Poland announced on Saturday that President Andrzej Duda had tested positive for the coronavirus at a time when the country’s de facto leader, Jaroslaw Kaczynski, was already in self-isolation after coming into contact with somebody earlier in the week who was infected.

The Belgian government, alarmed by the quickening pace of infections in the country of 11 million — the second-worst in Europe behind the Czech Republic — inched closer to a total lockdown with a spate of new restrictions on daily life. Officials moved up by two hours a curfew put in place last week, to 10 p.m. instead of midnight, for the next month, and required that all cultural and fitness venues such as gyms, pools, galleries and museums shut down. Commercial stores will be required to close at 8 p.m.

On Friday, several other countries, including France and Italy, recorded single-day records for new infections, according to data compiled by The New York Times. And the surge of new cases across the continent has pushed hospitalizations to alarming levels in countries such as Bulgaria, the Czech Republic and Hungary.

France, after months of falling numbers of patients in intensive care, is now facing a frightening second wave. It has recorded over 1 million cases and set a single-day record Friday with 42,032 new cases. The government this week expanded its nightly curfew to 38 more regions and Polynesia.

Local health authorities in Germany, who are responsible for the contact tracing of infected people, said they are increasingly overwhelmed, despite help from hundreds of soldiers who have been dispatched to communities across the country. In Frankfurt, a city of about 750,000 that serves as Germany’s banking capital, the number of new cases has quadrupled since the beginning of this month, and health officials there conceded that their ability to stop chains of infection had collapsed.

“It is no longer possible to trace each case,” the head of Frankfurt’s office of public health, René Gottschalk, told ZDF public television on Friday.

In Italy, which reported 19,143 new cases on Friday, officials are considering shuttering public gyms and swimming pools, according to a Reuters report. Bars and restaurants would be closed at 6 p.m. and people would be discouraged from traveling outside of their local areas.

The coronavirus has made a routine trip to the gym feel like a health threat.

Many epidemiologists consider gyms to be among the highest-risk environments, and they were some of the last businesses to reopen in New York City in early September.

Now, gyms must comply with a long list of regulations. Checking in requires a health screening; masks are mandatory, even during the most strenuous workouts; only one-third of normal occupancy is allowed; and everyone must clean, then clean some more.

At a Planet Fitness in Brooklyn, Dinara Izmagambetova, who wore a floral face mask and had a sheen of sweat after completing a two-hour workout, said she was thrilled to be back in a gym. But safety measures had made it a less sociable experience, she said.

“I could ask someone” how to use a machine before the outbreak, Ms. Izmagambetova said. “Now I’m doing a lot of Googling.”

But even as gyms have reopened, their future remains unclear. Some of them have had to shut down again after Gov. Andrew M. Cuomo recently designated parts of Brooklyn and Queens coronavirus hot spots.

Despite scientists’ concerns, infection clusters connected to gyms in the United States have been relatively rare so far, though they have been reported in Hawaii and California.

“We’re not seeing outbreaks tied to gyms as heavily as something like a bar or school,” said Saskia Popescu, an epidemiologist at George Mason University.

Still, a number of the 2,000 or so gyms in New York State and fitness centers across the country face a fight for life. At least one-fourth of the more than 40,000 gyms in the United States could close by the end of the year, according to the International Health, Racquet and Sportsclub Association, an industry group. A study by Yelp said that more than 2,600 already had.

As Colorado fights a spate of late-season wildfires, with residents hoping that a predicted blizzard on Sunday will finally bring things under control, the state’s governor is warning that the thick smoke spreading across mountain towns could hide coronavirus outbreaks.

“We do worry that the impact on respiratory conditions of the fires could mask the spread of Covid,” Gov. Jared Polis said at a news conference this week, asking residents to “please consider” getting tested if they have a cough or sore throat.

Crews in northern Colorado have spent several grueling days battling the East Troublesome fire amid 60-mile-an-hour wind gusts. Firefighters are struggling to control the 188,000-acre wildfire, which has destroyed an unknown number of homes while roaring through ranches, lakeside resorts and Rocky Mountain National Park.

Symptoms of smoke exposure such as wheezing, coughing and shortness of breath, are hard to distinguish from symptoms of the coronavirus, experts have said, making it difficult for many sufferers to know what is causing their discomfort.

“The early symptoms of Covid look a lot like breathing bad air for a period of hours,” Mr. Polis said.

Wildfire smoke can also make people more susceptible to catching the virus.

“When your immune system is overwhelmed by particles, it’s not going to do such a good job fighting other things, like viruses,” Sarah Henderson, a senior environmental health scientist at the British Columbia Centre for Disease Control, said this summer.

As of Saturday morning, there have been more than 92,000 confirmed coronavirus cases and 2,233 deaths in Colorado since the start of the pandemic, according to a New York Times database. Over the past week, the state has averaged almost 1,200 new cases per day, an increase of 81 percent from the average of two weeks earlier.

The day before its first kickoff of 2020, the Big Ten Conference was still unveiling rules for a football season that had been postponed, revived, truncated and compromised in efforts to contain the pandemic.

On Thursday, the conference announced a “no contest” rule for games canceled if team personnel tested positive for the virus — which seemed inevitable because the schedule has no bye weeks and, therefore, no wiggle room for last-minute changes. The intention is to play nine games in nine weeks to catch up to the three Power Five conferences that have already started.

But just over a month ago, no one thought the Big Ten — made up of 14 schools across the Midwest and Northeast — would begin football on Friday night, with the University of Illinois at the University of Wisconsin, even as the home team’s state ranked fourth in the country in per capita cases over the past seven days, and first among the states with Big Ten programs.

“Having football while I can’t go to class — in a way, it’s nice that we’re having this one thing that’s unifying,” said Anne Isman, a sophomore at Wisconsin who is living in an apartment in Madison. “At the same time, the timing feels a little off.”

Fans and parties will be barred from all of the league’s stadiums, but the precautions have not fully reassured the mayors of certain Big Ten towns.

They know that what happens at the stadiums will be only one part of football’s return. Fear of groups breaking recommended social-distancing protocols led 12 mayors of areas surrounding 11 Big Ten schools to send a letter to the conference this week, citing concerns about what bringing football back means for college towns as fans congregate to watch games — the virus an omnipresent risk freely floating between face paint, beer bottles and potlucks.

“We know the history of football games within our cities,” the mayors wrote. “They generate a lot of activity, social gatherings and consumption of alcohol.”

A spokesman for President Andrzej Duda of Poland said on Saturday that Mr. Duda had tested positive for the coronavirus and would go into isolation, just days after Jaroslaw Kaczynski, the deputy prime minister and head of the ruling party, entered quarantine after exposure to somebody who had been infected.

The announcement came amid a moment of crisis for Poland, which has been combating one of the most severe outbreaks in Europe, with hospital beds filling at an alarming rate.

Poland largely avoided the first wave of the pandemic by imposing an early lockdown in March, and nearly a third of its approximately 215,000 total cases have emerged in the past week.

The latest wave of cases has forced the country to implement new restrictions on public life and to convert the national stadium in Warsaw into a temporary field hospital that can accommodate 500 virus patients. Mr. Duda visited the stadium on Friday and met with site managers.

The new restrictions will require all cafes, bars and restaurants to close, except for takeout; gyms and swimming pools were also shut. Residents must use face coverings outside their homes, and remote teaching will become the norm for older children in primary schools, as well as in high schools and at universities.

Several months into the pandemic, Mr. Duda joined the ranks of leaders who have contracted the virus, including President Trump, Prime Minister Boris Johnson of Britain and President Jair Bolsonaro of Brazil.

The spokesman who announced Mr. Duda’s condition said he was “feeling well.”

global roundup

The Czech Republic’s prime minister has demanded the resignation of the country’s health minister after the health minister was photographed leaving a restaurant without a face covering.

The health minister, Roman Prymula, an epidemiologist who began his job in late September, has so far refused to resign. The prime minister has threatened to fire him, but he does not have the power to do so.

The Czech Republic is in the midst of the coronavirus crisis. Case are rising faster than anywhere else in Europe, with 78,211 cases recorded over the past week. The government has been imposing more and more restrictions in the hope of containing the spread of the virus.

Mr. Prymula had announced a partial lockdown beginning Thursday that closed shops and services, barred people from leaving their homes except for vital business and limited contact with people from other households. Restaurants, bars and cafes have been closed since Oct. 14, with the exception of carryout until 8 p.m. nightly.

Despite this, Mr. Prymula was photographed by a tabloid newspaper, Blesk, leaving the premises of a restaurant after midnight wearing no face mask after a meeting with a politician, Jaroslav Faltynek, who is first chairman of Prime Minister Andrej Babis’s ANO movement.

“Such a mistake cannot be excused,” Prime Minister Babis said on Friday at a news conference. “I do not care what Minister Prymula and Mr. Faltynek did there, who they invited and why. We cannot preach water and drink wine.” He said he would fire Mr. Prymula if he did not resign and that Mr. Faltynek will also be resigning his ANO post.

In refusing to resign, Mr. Prymula said at a news conference, “I did not break any rules, I walked through the restaurant to private premises.”

Though Mr. Babis can recommend that Mr. Prymula be fired, the president must agree and usually that is what happens. But President Milos Zeman has voiced doubts about the move in this case. The two were meeting in the afternoon.

In other developments around the world:

• Abdelmadjid Tebboune, the president of Algeria, said on Saturday that he would quarantine himself after senior government officials had been infected with the coronavirus. He said he was feeling well and that he would continue working during his quarantine.

• The Metropolitan Police arrested 18 protesters in London on Saturday following clashes between demonstrators and police that left three officers with minor injuries, the police said. The protest against lockdowns “attracted a large number of protesters,” with many not social distancing, violating coronavirus regulations, Cmdr. Ade Adelekan said.

A day after the nation hit a new high for coronavirus cases, President Trump returned to the campaign trail for a series of rallies and again sought to minimize the surging pandemic, mocking his rival, Joseph R. Biden Jr., for following the social distancing recommendations of public health officials.

In the face of spiking numbers, Mr. Trump on Saturday continued to lean into the idea that the news media and his critics are obsessing about the virus, even as polls show widespread public concern. A recent New York Times/Siena College poll found that a slim majority of voters — including half of independents — believe the worst of the pandemic is yet to come.

With 10 days left until the election and hundreds of thousands of voters expected to cast their ballots as long lines marked the first weekend of early in-person voting in Florida, New York, Wisconsin and other states, Mr. Trump and Mr. Biden presented sharply divergent cases, both in words and actions, for how they would handle the pandemic still gripping the country.

Campaigning in the key battleground of Pennsylvania, Mr. Biden cited the milestone in cases at a drive-in rally in the Philadelphia suburbs on Saturday and criticized Mr. Trump for asserting that the country was “rounding the corner” as cases spike.

The beeping of car horns punctuated his remarks, a familiar soundtrack at his socially distanced drive-in events in the weeks before Election Day. “I wish I could go car to car and meet you all,” Mr. Biden said. “I don’t like the idea of all this distance, but it’s necessary. I appreciate you being safe. What we don’t want to do is become superspreaders.”

In North Carolina, it seemed that Mr. Trump had watched his rival’s event, mocking Mr. Biden for his careful crowd limits. “People in cars,” Mr. Trump said. “I don’t get it.”

But the virus’s surge has ensured that even Mr. Trump’s well-attended rallies can be a political liability, a reminder to voters fearful of the pandemic of his regular disregard for expert and public health advice.

Mr. Trump used his own contracting of the disease, his weekend of hospitalization and subsequent recovery as a pitch to minimize the severity of a pandemic that has cost more than 224,000 lives in the United States out of more than eight million cases.

The United States is in the midst of one of the most severe surges of the coronavirus to date, with more new cases reported across the country on Friday than on any other single day since the pandemic began.

Since the start of October, the rise in cases has been steady and inexorable, with no plateau in sight. By Friday night, more than 85,000 new cases had been reported across the country, breaking a single-day record set on July 16 by more than 9,000 cases.

By that measure, Friday was the worst day of the pandemic, and health experts warned of a further surge as cold weather sets in.

For many, the soaring numbers brought back ragged memories of what it was like in mid-July, when the virus was raging through the Sun Belt.

Raymond Embry saw the worst of it up close. His small Arizona medical clinic had been giving about five coronavirus tests a day. That grew to dozens a day, and then came the surge on July 16, with 4,192 people lined up for tests to find out if they had the coronavirus.

That day, arguably the worst of the pandemic in the United States to that point, set records nationwide. By the end of that 24-hour period, a staggering 75,687 new cases had been reported around the country, and Arizona led the nation in deaths per capita.

On the Texas-Mexico border, mid-July was a nightmare. Johnny Salinas Jr., the owner of Salinas Funeral Home, was handling six to seven funerals a day, a number he would usually see over a week before the pandemic. Some of those included family members and relatives of employees.

But in some other parts of the country that day, the virus felt far away.

On July 16, towns in North Dakota were holding their annual summer festivals. People cheered the rodeos and danced together, maskless, in the streets.

With Covid-19 hospitalizations spiking again in many parts of the country, public health officials have expressed concerns about a perennial source of strain on the health care system: seasonal flu. As threats of a “twindemic” loom, health care workers have stressed the need for vaccination and other preventive measures to slow the spread of flu.

One insurance company is going further to try to mitigate the effects of flu season: UnitedHealthcare, the country’s largest health insurance company, plans to provide 200,000 at-risk patients with kits that include Tamiflu, the prescription antiviral treatment; a digital thermometer; and a coronavirus P.C.R. diagnostic test. People can take the test at home and mail it in for laboratory analysis, helping patients and doctors determine the cause of their symptoms. That’s important because the coronavirus and flu have similar symptoms but require different treatments.

“These viruses have proven themselves highly capable of putting strain on our health care system alone,” said Dr. Kelly Moore, an associate director of the Immunization Action Coalition. “Their combined impact is really worrisome.”

In late September, UnitedHealthcare began inviting its Medicare Advantage members to sign up for the kits either online or by phone, starting with a focus on those at highest risk for complications from Covid-19 and the flu, based on their age and health status. Since then, 120,000 people have enrolled, and the company has begun shipping the kits. The company has more than five million Medicare Advantage members.

With early voting underway and the election days away, many U.S. cities and states have imposed safety measures to protect voters and poll workers from exposure to the coronavirus.

But polling places could still become “mass gathering events,” the Centers for Disease Control and Prevention warned in an advisory released on Friday, adding that measures to prevent the spread of Covid-19 could be improved.

The C.D.C. based its latest advice on a survey of 522 poll workers in Delaware’s statewide primary in September. That survey did not indicate whether any cases of Covid-19 were linked to the voting centers.

Guidelines issued by the agency in June recommended various ways to minimize crowds at polling locations, including absentee voting, extended voting hours and the use of protective gear by poll workers assisting voters with coronavirus symptoms.

The C.D.C. also recommended putting up physical barriers between voting machines, spacing the machines apart from one another, indicating 6-foot distances with signs or floor markings for those waiting in line to vote and allowing curbside voting for people who are ill, among other measures.

The advisory published on Friday said that “a substantial proportion” of poll workers in the Delaware study saw incorrect mask use by voters, and said that “further messaging on proper mask use, including at polling locations, might be needed to strengthen the effectiveness of masks during upcoming elections.”

“Ensuring that ill voters can vote while maintaining poll worker and voter safety will be essential to minimizing transmission without restricting voting rights,” the advisory added.

But in Alabama, where curbside voting had been allowed, the state’s attorney general has ordered that it be stopped. On Wednesday, the U.S. Supreme Court upheld the ban.

For his third rally on Saturday, President Trump arrived in Waukesha, Wis., saying he felt better after he was hospitalized for Covid-19 than he did before. His only acknowledgment of the spiking rates of the virus in Wisconsin, where there were 4,626 new cases and 46 deaths a day before his visit, was to claim that the United States included in its death counts people suffering from other ailments, like heart conditions.

“If we did half the testing, we would have half the cases,” he told the crowd. “If they cut that in half, we would have another half cut.”

Later, Mr. Trump said, “We’re rounding the turn,” and called it “terrible” that former Vice President Joseph R. Biden Jr. warned of a dark winter during Thursday’s debate. In Wisconsin, over the past week, there have been an average of 3,547 cases per day, an increase of 39 percent from the average two weeks earlier. The U.S. set a new record for Covid-19 infections on Friday.

“We have to get out,” Mr. Trump told a cheering crowd of supporters. “Our economy will be greater than ever before.”

Mr. Trump said that he “got a lot of credit” for his toned-down performance at the last debate. But he admitted he preferred his combative, interrupting performance that his internal campaign polls showed had cost him support.

“You know who liked my performance the first time better? The Hispanics,” he added.

Mr. Trump continued to play down the positive cases reported in the United States, arguing that someone can be “close to death” of another ailment, like a heart condition, “and they get Covid, they put it down to Covid.”

The latest coronavirus surge is raging across the American heartland, most acutely in the Midwest and Mountain West.

This harrowing third surge, which led to a U.S. single-day record of more than 85,000 new cases Friday, is happening less than two weeks from Election Day, which will mark the end of a campaign dominated by the pandemic and President Trump’s much-criticized response to it.

As of Friday evening, 15 states have added more cases in the past week than in any other seven-day stretch of the pandemic: Wisconsin, a battleground in the presidential election, Colorado, Kentucky, Illinois, Wyoming, Idaho, Utah, South Dakota, Montana, Arkansas, Alaska, Tennessee, Ohio, Indiana and North Dakota. And four states have added more deaths this week than in previous weeks: Wisconsin, Kentucky, South Dakota and Oklahoma.

North Dakota leads the nation in coronavirus cases per capita. Illinois is averaging more than 4,100 new cases per day, up 85 percent from the average two weeks ago. And Pennsylvania, another battleground state, on Friday reported a record of 2,258 cases.

The virus will be front of mind for voters in several key states: in Ohio, where more people are hospitalized than at any other time during the pandemic, and especially Wisconsin, home to seven of the country’s 10 metro areas with the highest numbers of recent cases. On Friday, the Wisconsin Supreme Court blocked Gov. Tony Evers’ emergency order restricting the size of indoor gatherings to 25 percent capacity on Friday.

Experts worry that the growing numbers in need of hospital care will only get worse if cases continue to mount, especially in rural areas where medical facilities could be quickly overwhelmed.

Citing a rise in hospitalizations across the state, the Colorado Department of Public Health and Environment announced a strengthening of coronavirus restrictions in certain counties, capping gatherings at 10 people from no more than two separate households. For the third straight day, Colorado announced a new single-day cases record on Friday (eight more states also set records Friday).

Overnight, nearly 2,500 people were hospitalized in Illinois, the state’s top public health official, Dr. Ngozi Ezike, said in a news conference Friday afternoon. The mayor of Chicago, Lori E. Lightfoot, announced a curfew on nonessential businesses beginning at 10 p.m. on Friday.

In the latest presidential debate on Thursday night, President Trump asserted that the virus was “going away” as he defended his management of the pandemic. Former Vice President Joseph R. Biden Jr., the Democratic nominee, attacked Mr. Trump’s handling, calling for much more aggressive federal action for the “dark winter” ahead.

President Trump and many supporters blame restrictions on business activity, often imposed by Democratic governors and mayors, for prolonging the economic crisis initially caused by the virus. But the experience of states like Iowa, which recently set a record for patients hospitalized with Covid-19, shows the economy is far from back to normal even in Republican-led states that have imposed few business restrictions.

Iowa was one of only a handful of states that never imposed a full stay-at-home order. Restaurants, movie theaters, hair salons and bars were allowed to reopen starting in May, earlier than in most states. Many businesses worry they won’t be able to make it through the winter without more help from Congress. Others have already failed.

Defying the guidance of infectious disease experts, who say that universal masking and social distancing are essential to limiting the virus’s spread, has eroded support for both Mr. Trump and Gov. Kim Reynolds in Iowa, especially among voters over 65, normally a solid Republican constituency, according to public and private polls. Mr. Trump and Senator Joni Ernst — whose seat could play a decisive role in determining control of the Senate — are both in tight races in a state that the president easily won four years ago.

The high case count in part reflects increased testing. With about one million people tested on many days, the country is getting a far more accurate picture of how widely the virus has spread than it did in the spring.

But public health officials warn that Americans are heading into a dangerous phase, as cooler weather forces people indoors, where the virus spreads easily. It could make for a grueling winter that tests the discipline of the many people who have grown weary of masks and of turning down invitations to see family and friends.

Late-stage coronavirus vaccine trials run by AstraZeneca and Johnson & Johnson have resumed in the United States after the companies said Friday that serious illnesses in a few volunteers appeared not to be related to the vaccines.

Federal health regulators gave AstraZeneca the green light after a six-week pause, concluding there was no evidence the experimental vaccine had directly caused neurological side effects reported in two participants. The AstraZeneca news was first reported by The Wall Street Journal.

Johnson & Johnson said that its trial, which had been on pause for 11 days, would restart after a company investigation determined that a “serious medical event” in one study volunteer had “no clear cause.” To maintain the integrity of the trial, the company said, it did not check whether the volunteer received the vaccine or the placebo.

Dr. Luciana Borio, a former acting chief scientist at the Food and Drug Administration, welcomed the announcements, citing the urgent need for multiple vaccines to remain in the race for a product that could protect the global population from the coronavirus, which has already killed more than a million people worldwide.

“The demand for safe and effective Covid vaccines exceeds any single manufacturer’s production capacity,” Dr. Borio said. “We really need several in the field.”

An F.D.A. spokesperson declined to comment on Friday afternoon.

AstraZeneca and Johnson & Johnson are two of the four companies now in late-stage clinical trials in the U.S. for experimental coronavirus vaccines. Both companies are using adenoviruses, which typically cause harmless colds. The adenovirus is engineered so that it can chauffeur a coronavirus gene into human cells.

Their two high-profile competitors, Moderna and Pfizer, also in advanced trials, are instead using a technology based on genetic material known as mRNA. Delivered into human cells, the mRNA prompts the production of coronavirus proteins, triggering an immune response.

AstraZeneca moved swiftly into clinical trials, enrolling thousands of volunteers for its vaccine trials around the world in countries including Brazil, India, South Africa and Britain. A large, late-stage trial kicked off in the United States at the end of August. But all the trials were halted days later, on Sept. 6. A volunteer who had received the vaccine in the United Kingdom reportedly experienced symptoms of transverse myelitis, or inflammation of the spinal cord, triggering a global pause to the company’s efforts.

The incident sparked some concern among experts, who noted that a similar adverse neurological event, reported months ago, had occurred in another vaccinated volunteer. While this earlier event prompted its own pause in AstraZeneca’s trials, an independent safety board ultimately determined it was unrelated to the vaccine, allowing studies to resume.

Following the second AstraZeneca halt in September, trials abroad rapidly resumed in most countries. But the American hiatus persisted, with few details released as to why.

According to two vaccine experts familiar with the situation who were not authorized to discuss it publicly, the F.D.A. did not directly tie the vaccine to the two neurological illnesses, although it could not be ruled out. The agency has advised the company to alert study volunteers about related symptoms like weakness and numbness that might point to a milder case of transverse myelitis, the experts said.

Johnson & Johnson launched their Phase 3 trial on 60,000 volunteers in September. On October 12, the company announced its own trial pause, citing concerns that an illness had happened in one of its volunteers as well. The company has kept mostly quiet about the details of the incident.

“There are many possible factors that could have caused the event,” the company said. “Based on the information gathered to date and the input of independent experts, the Company has found no evidence that the vaccine candidate caused the event.”

Adverse events are not uncommon in large-scale vaccine trials. In some cases, they are caused by a vaccine. But investigations usually reveal that they’re coincidental — a simple matter of chance.

Before the pauses, both companies had indicated they would likely submit their vaccines for emergency authorization from the Food and Drug Administration within a few month’s time — perhaps even by year’s end. It remains unclear how much these plans have now been thrown into flux in the wake of trial delays. Results from AstraZeneca’s late-stage trials are still expected later this year, according to the statement. Johnson & Johnson did not provide an updated estimate in their statement.