An essential worker uses a tool to take a self-administered Covid-19 test from a car at a testing site in Chicago.
Credit…Taylor Glascock for The New York Times

The United States reported a record of more than 500,000 new cases over the past week, as states and cities resorted to stricter new measures to contain the virus that is raging across the country, especially the American heartland.

The record was broken Tuesday, even as the Trump administration announced what it called its first-term scientific accomplishments, in a press release that included “ENDING THE COVID-19 PANDEMIC” written in bold, capital letters.

The record reflects how quickly the virus is spreading. It took nearly three months for the first 500,000 coronavirus cases to be tallied in the United States — the first was confirmed on Jan. 21, and the country did not reach the half-million mark until April 11. Testing was severely limited in the early days of the pandemic.

The new restrictions range from a nightly business curfew in Newark, N.J., to a two-week stay-at-home order in El Paso, Texas, to a halt in indoor dining in Chicago.

Illinois Gov. J.B. Pritzker announced on Tuesday that he was stopping indoor dining and bar service in Chicago, effective at 12:01 a.m. Friday, Oct. 30.

The city joins New York and Wisconsin, states that earlier this month issued restrictions or outright bans on indoor dining in restaurants and bars to limit the spread of the coronavirus. The restrictions have been loudly opposed by a restaurant industry that has been decimated by the pandemic.

Chicago is now averaging more than twice as many coronavirus-related hospital admissions per day as it was a month ago, Mr. Pritzker’s office said, and the share of tests that are coming back positive has almost doubled since the beginning of October.

The U.S. has reported a record daily average of about 71,000 new cases over the past week, an increase of about 40 percent from the average two weeks earlier. Twenty states, including Illinois, have recorded their highest seven-day average of new cases, and three states (Tennessee, Wisconsin and Oklahoma) have set a record seven-day average for deaths. On Tuesday, Oklahoma and Wyoming broke single-day death records and Kentucky reported a new daily cases record.

Mr. Pritzker’s announcement follows a similar indoor dining ban that includes southern Cook County, just outside Chicago, which was announced Monday.

In Chicago, outdoor service will be allowed if tables are spaced six feet apart; reservations are required, and service shuts down at 11 p.m. All social gatherings in the city will be limited to 25 people or 25 percent of the venue’s capacity, whichever is less.

“We can’t ignore what is happening around us,” Mr. Pritzker said in a statement. “Because without action, this could look worse than anything we saw in the spring.”

Other communities around the country that have also recently tightened restrictions include:

  • El Paso County, Texas, imposed a two-week stay-at-home order and a 10 p.m. to 5 a.m. curfew that took effect Sunday. The number of people hospitalized in the El Paso metropolitan area with Covid-19 has more than tripled over the past three weeks. Officials are scrambling to make space for them by setting up overflow beds in a convention center and under tents in parking lots and by flying patients out to medical centers outside the area.

  • In Newark, N.J., all nonessential businesses began closing at 8 p.m. Tuesday. As of Sunday, the three-day average citywide positivity rate was 11.2 percent, more than double the statewide rate for the same period, the city said Monday.

  • Gov. Brad Little of Idaho ordered the state on Monday to return to Level 3 restrictions including limiting indoor gatherings to 50 people, requiring masks at long-term care facilities, and restricting bars and restaurants to serving only customers who are seated at tables. Idaho is averaging around 900 cases each day, up from about 260 in mid-September.

  • New mask mandates, the first in North Dakota, were imposed last week in the cities of Fargo and Minot. About 5 percent of all North Dakotans have now tested positive for the virus, the highest rate of any state.

  • In Milwaukee, new rules take effect Thursday that limit the size of gatherings and restrict restaurants and bars to 25 percent of their capacity unless they receive a waiver from the state health department. A field hospital at the Wisconsin state fairgrounds west of Milwaukee has started accepting patients.

  • The Blackfeet Indian Reservation, in Montana, extended its stay-at-home order on Friday to remain in effect through Nov. 8.

  • The Oglala Sioux Tribe has locked down its Pine Ridge Indian Reservation in South Dakota until Oct. 30 in response to new coronavirus cases, according to the Rapid City Journal.

  • After an appeal from local hospitals, the mayors of two small Missouri cities, Nixa and Ozark, imposed their first mask mandates last week.

  • In Louisiana, a statewide mask mandate and other coronavirus restrictions were up in the air on Tuesday, after Republican legislators used an obscure clause in state law to suspend the public health emergency declared by the governor. Gov. John Bel Edwards, a Democrat, had a quick response: He sued.

Gov. Gavin Newsom of California launched a group of western states that will review any federally approved vaccines.
Credit…Rich Pedroncelli/Associated Press

A week after Gov. Gavin Newsom of California announced that a panel of experts from his state would independently review any federally approved coronavirus vaccines before they were administered to residents, the governors of Washington, Oregon and Nevada announced they’d join California’s effort.

The move comes as leaders across the country face a vaccine-development process that many have said they fear is becoming overly politicized.

“We believe in science, public health and safety,” Gov. Jay Inslee of Washington said in a statement. “That is why I am pleased that Washington is joining California and other western states in this effort.”

In September, Gov. Andrew Cuomo of New York announced that his state would independently review any vaccines, saying President Trump had politicized the approval process.

“Frankly, I’m not going to trust the federal government’s opinion,” Mr. Cuomo said at the time.

But in a news briefing on Tuesday, Mr. Newsom emphasized that the extra review was meant to reinforce federal findings and to ensure that the Western states have planned in detail who should be able to receive what are expected to be very limited early doses. It would not, he said, stall or add an additional layer of politics to the process.

“It will not cause delays,” Mr. Newsom said. “It’s going to increase transparency and trust.”

About two-thirds of Californians surveyed in a recent poll by the Public Policy Institute of California said they were concerned about the development of a vaccine moving too quickly.

California’s health secretary, Dr. Mark Ghaly, added that the review would not involve continuing or duplicating any vaccine trials. Rather, the panel will look at data and other information, “a lot of which is publicly reported, through the eyes of experts,” he said.

The review will allow the states to plan for a complex distribution process in detail and with equity in mind.

“The independent review conducted by this panel of doctors, scientists, and health experts will ensure that a safe and effective Covid-19 vaccine is available to everyone, especially communities that have been disproportionately impacted by this disease,” Oregon’s governor, Kate Brown, said in a statement.

This isn’t the first time the governors have collaborated across state lines but outside the purview of the federal government. In April, as many states held back on implementing pandemic-related restrictions, California, Oregon, Washington, Nevada and Colorado formed a so-called Western States Pact.

Mr. Newsom said the group was largely a way of sharing best practices, rather than a formal agreement to act in concert.

Governors have been also outspoken lately about how they think the distribution of vaccines should be handled. Earlier this month Mr. Cuomo, as head of the bipartisan National Governors Association, posed additional questions about how the Trump administration will ensure that states are able to get and distribute vaccines.

Pfizer is one of four companies with large, late-stage clinical trials underway in the United States.
Credit…Brendan Mcdermid/Reuters

After weeks of dangling the possibility of early coronavirus vaccine results by October, Pfizer’s chief executive said Tuesday that would now be nearly impossible.

The announcement, by Dr. Albert Bourla, came on the same day that Pfizer announced third-quarter earnings, and all but ruled out the possibility of early results before the presidential election next Tuesday. President Trump had long sought to tie the possibility of positive vaccine news to his own prospects for re-election.

In a call with investors on Tuesday, Dr. Bourla was pushed by Wall Street analysts to be more specific about when the company would have an idea of whether early results could show whether its vaccine is effective, and how much detail the company would provide when it is. Pfizer is one of four companies with large, late-stage clinical trials underway in the United States.

In his remarks, he acknowledged the urgency of developing a vaccine amid a global resurgence in infections. In the United States over the past week, there have been an average of more than 71,000 coronavirus cases per day, and hospitalizations are increasing, too.

“Let’s be very patient — I know how much the stress levels are growing,” Dr. Bourla said. “I know how much the vaccine is needed for the world.” He also pushed back against any suggestion that politics were motivating the speed of development, saying “this is not a Republican vaccine, or a Democrat vaccine.”

Pfizer’s clinical trial is testing the vaccine in 44,000 people, half of whom have received a vaccine and half who have gotten a placebo. The trial’s protocol, or blueprint, allows for an initial look at results after at least 32 people in either group have developed Covid-19. If more than 26 of those people are in the placebo group, then the vaccine is considered likely to be effective.

Dr. Bourla had repeatedly predicted that the initial analysis — which is conducted by an outside board of scientific experts — would come by the end of October. But on Tuesday, he said those 32 cases of Covid-19 had not yet occurred, a sign that the trial is progressing more slowly than the company had estimated. He also said the outside panel would need at least a week to analyze any results, making an answer before the election unlikely. Dr. Bourla said the company would report results if the outside board found the vaccine was either effective or not, but not if there is no definitive conclusion either way.

Even if early results come over the next few weeks, most Americans are not likely to get the vaccine anytime soon. Under guidelines from the Food and Drug Administration, coronavirus vaccine developers must turn in at least two months of safety data after half of the trial’s participants have received the second dose of the vaccine, which Pfizer has said will not happen until at least the third week of November.

Dr. Bourla said the company has already manufactured “hundreds of thousands” of doses. It expects to have at least 40 million doses by the end of the year, and 100 million doses by next March.

The Kansas State marching band. The university is one of a few to have shown progress in containing the virus.
Credit…Charlie Riedel/Associated Press

When college students returned to campus this fall, jamming sidewalks and bars in the surrounding communities, many college towns emerged as major coronavirus hot spots.

In many college towns, that’s still true: Washtenaw County, home to the University of Michigan, saw its largest number of confirmed cases of the pandemic this month, despite a stay-at-home order for undergraduates that was meant to squash outbreaks.

In Wisconsin, especially around colleges, new case counts remain stubbornly high, with the virus now spreading to vulnerable populations.

But some college towns have shown progress: After spikes in August and September, reports of new infections at several large universities have slowed markedly.

At Penn State University’s flagship campus in State College, Pa., 10.7 percent of students who were tested in mid-September were positive, according to the campus tracker, while the surrounding Centre County had a 12.1 percent positivity rate around the same time. Those rates have since fallen by more than half: From Oct. 16 to 25, only 4.5 percent of tested students were positive, tracking with the county’s rate of 5 percent.

The number of active coronavirus cases around the Kansas State campus shot up more than 400 percent in early September, a few weeks after students returned for the fall semester. By late September, the school’s test positivity rate, according to its campus dashboard, was 5.41 percent. That dropped to 2.2 percent for tests in mid-October, the most recent figure available.

To the east in Lawrence, the University of Kansas has seen a similar turnaround: the campus positivity rate of nearly 11 percent in early September fell to 1.44 percent in mid-October.

The counties surrounding the two Kansas schools still have higher rates of the virus, however, suggesting that campus outbreaks have spread to surrounding communities.

Americans are divided sharply along partisan lines over whether colleges should have brought students back to campus, according to the Pew Research Center. Those who tend to vote Republican were more than twice as likely as those who support Democrats to say that it was the right decision.

A New York Times survey of more than 1,700 American colleges and universities has found more than 214,000 coronavirus cases tied to campuses, and at least 75 deaths since the pandemic began. The vast majority of those cases have come in the fall.

A couple wearing face masks during the summer  in Beverly Hills, California.
Credit…Mario Anzuoni/Reuters

Despite President Trump’s very public resistance to mask-wearing for much of this year, a newly released survey from the Centers for Disease Control and Prevention shows that a vast majority of Americans of all ages have been wearing face coverings since April.

The data, released in the agency’s weekly Morbidity and Mortality Report, is roughly in line with other polls showing that most Americans report wearing masks, at least when they are inside stores.

For example, Pew Research reported in August that 85 percent of 13,200 adults they surveyed said they wore masks in stores, up from 65 percent in June.

In a National Geographic poll released early this month, 92 percent of 2,200 Americans surveyed said they always or sometimes wore a mask when leaving the house.

The C.D.C. data, based on three monthly surveys with about 2,000 Americans each time, cover only the period from April to June.

A C.D.C. spokesman attributed the delay in the release of the surveys findings because of “the overwhelming amount of research going on at the agency.”

The survey asked about six risk-mitigation behaviors: mask-wearing, hand-washing, keeping six feet away from others, canceling social activities, avoiding crowds and avoiding restaurants.

In general, the older respondents were, the more of those measures they took. But as early as April, 70 percent of all those aged 18 to 29 reported wearing masks, while 84 percent of those older than 60 did.

By June, 86 percent of young Americans said they were wearing them while 92 percent of the seniors said they were.

Frequent hand-washing or sanitizing was equally popular, but it dropped slightly among all age groups from April to June as scientists realized that the virus was more likely to be transmitted by a mist of tiny droplets than by picking it up from surfaces.

The least popular measures among all age groups were “canceling or postponing pleasure, social or recreational activities” and “avoiding all or some restaurants.”

In their analysis of the data, the authors observed: “Lower engagement in mitigation behaviors among younger adults might be one reason for the increased incidence of Covid-19 cases in this group, which have been shown to precede increases among those 60 years or older.”

The findings, the authors concluded, show the need for clear advice for Americans, “especially for young adults,” to protect themselves, including by wearing masks.

On Friday, Dr. Anthony S. Fauci, the nation’s top infectious disease expert, said on CNN that “if people are not wearing masks, then maybe we should be mandating it.”

European roundup

Italian Premier Giuseppe Conte, right, says another nationwide lockdown would be unavoidable if people ignore the latest restrictions. 
Credit…Pool photo by Fabio Frustaci

The Italian government approved a series of measures Tuesday to assist businesses hardest hit by the new restrictions introduced by the government as it sought to control a sharp rise in coronavirus infections in the country.

On Sunday, the government announced the new rules, which ordered bars and restaurants to close at 6 p.m. and shut cinemas, theaters and gyms until Nov. 24. That set off a series of protests in Catania, Milan, Turin and other cities and hundreds of demonstrators blocked traffic, set off firecrackers, burned garbage cans and clashed with the police as they protested on Monday. Many chanted: “Freedom, freedom.” Protests continued in Rome on Tuesday.

At a news conference Tuesday evening, the Italian prime minister, Giuseppe Conte said that the government had set aside “more than five billion” euros to give “immediate resources” to the businesses most affected by the restrictions, including “restaurants, cafes, pizzerias, bakeries, ice cream parlors — but also theaters, cinemas, gyms and pools, to name a few.”

Mr. Conte said that Italy’s tax agency would transfer funds into people’s bank accounts, “the fastest and most efficient method that we had tried so far.” He said the funds would arrive by mid-November. The measures also include tax breaks and one-off payments for people in the entertainment industry.

Italy has recorded an average of 17,000 new cases a day over the last week. The country, which was hit hard during the first wave of the virus, has reported 564,778 total cases and at least 37,700 deaths. On Tuesday, the government reported 21,993 new coronavirus infections in the last 24 hours.

After a monthslong lockdown earlier this year, Italian bar and restaurant owners said the new restrictions would force many to close for good. Some placed signs in store windows that read: “Forced to close at 6 p.m., but it is our right to have a future.”

A petition by leaders of Italy’s entertainment industries, as well as directors and actors, said that the new closures were unjustified, given the strict protocols that had been in place since the summer. After protests on Friday turned violent in Naples, one city where an overnight curfew had already gone into effect, Italy’s interior ministry warned that the demonstrations had been infiltrated by individuals who were trying to stir up trouble, though peaceful protests were also held in several cities.

These acts of violence “have nothing to do with forms of civil dissent and the legitimate concern of entrepreneurs and workers related to the difficult economic situation,” Interior Minister Luciana Lamorgese said in a statement. She said that prosecutors were investigating the protests.

In other developments around Europe:

  • In Spain, hundreds of demonstrators gathered in Barcelona on Monday to protest the nighttime curfew that came into force a day earlier, as part of Spain’s latest state of emergency. The protest ended with some demonstrators clashing with police officers and burning trash containers. Barcelona’s local police estimated that about 800 people took part in the demonstration, with one of them detained. And on Tuesday, Spanish doctors staged a nationwide walkout to protest work conditions and hiring policies in the country’s public health care system. Hospitals were able to continue operating with minimal staffing. The doctors plan to repeat the protests on every last Tuesday of the month until the government increases resources.

  • Resistance to new rules is also hardening in northern England, where lawmakers urged Britain’s prime minister, Boris Johnson, to create a “clear road map” out of lockdown restrictions and asked for economic support, saying the region was being disproportionately affected by the pandemic. Northern England has seen “disruption unparalleled to other parts of the country,” more than 50 members of Mr. Johnson’s Conservative Party said in a letter, adding that the pandemic had exposed systemic disadvantages between the country’s northern and southern regions. Officials have imposed the country’s harshest restrictions on parts of England’s north, including the cities of Liverpool and Manchester, with pubs, gyms and some other nonessential businesses closed. But local officials have feuded with the government on providing lifelines for the region’s economy, while some residents have taken issue with seemingly contradictory rules.

  • Coronavirus infections have risen sharply in Greece, spurring the authorities to announce lockdowns for two more northern regions starting Thursday. The decision to lock down Serres and Ioannina, home to around 350,000 people, came after health authorities announced a record number of new cases nationwide on Tuesday. The regions of Kozani and Kastoria were locked down earlier this month. Additional restrictions, including a mask mandate and a nighttime curfew, took effect in several other regions, including greater Athens and Thessaloniki, which the authorities said is “on the verge” of a lockdown. Greece did well early in the pandemic, but the spread of the virus has accelerated in recent weeks. The country has recorded 32,752 cases and 593 deaths.

  • Poland’s prime minister, Mateusz Morawiecki, on Tuesday called for an end to mass protests over abortion rights, saying that demonstrators were disregarding “massive risks” from the coronavirus pandemic. Poland has seen five days of nationwide protests after a ruling by a constitutional tribunal last week that amounts to a near-total ban on abortion in the predominantly Catholic nation. Poland has been seeing a surge in daily cases, with more than 16,000 reported on Tuesday. The country has reported at least 80,600 cases in the past seven days.

Global Roundup

Pedestrians in Moscow earlier this month. Russia mandated masks in public on Tuesday after recording more than 100,000 cases in a week. 
Credit…Dimitar Dilkoff/Agence France-Presse — Getty Images

The Russian government on Tuesday made its most aggressive move yet to try to stem a second wave of the coronavirus, mandating masks in public places throughout the country.

The federal health watchdog agency, Rospotrebnadzor, also urged the governors of Russia’s 85 regions to order restaurants and entertainment venues to close by 11 p.m. Masks must be worn in taxis, public transportation, elevators and parking garages, and in any place where more than 50 people are able to gather, according to the order published on the watchdog’s website. Officials offered no immediate details on how the order would be enforced.

The directive was unusual because President Vladimir V. Putin has resisted taking any nationwide measures to stop the virus’s spread in recent months, delegating the battle to regional leaders. And after a nationwide lockdown in April and May caused widespread economic pain, officials have been loath to order any new business closures, even as the infection rate reached new heights in recent weeks.

In another measure of the virus’s spread, a number of top officials have been exposed or infected. Sergey V. Lavrov, the foreign minister, entered self-quarantine Tuesday after having had contact with someone who tested positive for the virus. The speaker of the lower house of parliament, Vyacheslav V. Volodin, told Mr. Putin on Monday that 91 of the assembly’s 450 representatives have or have had the coronavirus — and that 38 are currently hospitalized with the infection.

Russia has recorded more than 1.5 million cases of the virus, with more than 114,00 of those coming in the past seven days, and a total of 26,000 deaths.

Elsewhere around the world:

  • The mayor of Mexico City has tested positive for the coronavirus, becoming the most high-profile politician in Mexico to contract the virus as the country struggles to contain a rise in new cases. In a tweet posted Tuesday, the mayor, Claudia Sheinbaum, said she did not have symptoms and would continue to “coordinate all activities from a distance, with the same commitment as usual.” Mexico’s dense capital — the center of its pandemic — has been grappling with a recent surge in hospitalizations, which had been declining even after much of the city reopened in July following a lockdown.

  • Hong Kong’s seven-day average of locally transmitted cases has gradually decreased since mid-October, said Sophia Chan, the city’s health secretary. In response, the number of people allowed at each table in restaurants will increase to six from four starting Friday, Ms. Chan said, even though the limit on public gatherings will remain at four people. Bars and nightclubs may also seat up to four people per table, and the city’s beaches will soon reopen to the public.

The Port Authority of New York and New Jersey will impose a $50 fine to passengers who do not wear masks at JFK, La Guardia and Newark airports as well as on the PATH and two bus terminals.
Credit…Shannon Stapleton/Reuters

As the holiday travel season approaches, the Port Authority of New York and New Jersey, which operates the New York City region’s biggest airports, said on Tuesday that it would soon impose a $50 fine on travelers who do not wear a mask or face covering.

The agency, which in addition to operating Kennedy International, La Guardia and Newark Liberty International airports also oversees the PATH train system and two major bus terminals, said it would begin issuing fines on Monday. It was unclear how the agency planned to enforce the fine.

The Port Authority has required masks in its facilities and on its transit system for months but was not fining those who did not comply. The Metropolitan Transportation Authority, which operates New York City’s subways and buses and two of its commuter rail lines, last month began issuing a $50 fine against riders who did not wear masks.

“The Port Authority will continue to put primary emphasis on voluntary compliance,” a Port Authority spokeswoman, Lindsay Krysak, said in an email on Tuesday, adding that police officers would “continue to remind people who aren’t wearing masks to put one on, and offer up masks to people who have forgotten theirs or have a broken mask, things like that. But travelers should know they could be liable for a $50 fine starting Monday if they refuse to wear their mask.”

The announcement of the fine comes as coronavirus cases keep rising around the country, including in parts of New Jersey near New York City, and as officials in New York have warned that interstate travel could bring about further spread.

Earlier on Tuesday, Mayor Bill de Blasio of New York City urged residents not to leave the state during the holidays, noting the threat of a second wave that so far the city has seemed to avoid.

“I have to urge all New Yorkers: Do not travel out of state during the holidays,” he said. “You could be putting yourself and your family in danger.”

Gov. Andrew M. Cuomo of New York has also warned residents not to make unnecessary out-of-state trips, including to neighboring states that have seen an increase in cases compared with New York.

On Tuesday, Mr. Cuomo announced that while an uptick of cases in Massachusetts had become significant enough to trigger New York’s restrictions, travelers from that state would not be required to quarantine upon arrival.

Massachusetts joins New Jersey, Connecticut and Pennsylvania on a list of New York’s neighbors that are not on the state’s travel advisory, which requires a two-week quarantine, despite meeting the qualifications.

In a statement, Mr. Cuomo said that Massachusetts was too “interconnected” with New York for a quarantine requirement to be practical or effective. He used similar language last week when he exempted the other three states from the advisory.

Of particular concern were the huge numbers of commuters who cross state borders from New Jersey and Connecticut, which share transit links with New York.

Still, Mr. Cuomo said Tuesday that all nonessential travel between New York and Massachusetts should be avoided. Massachusetts’ western edge abuts New York, and its southern edge shares a boundary with Connecticut.

New Jersey and Connecticut, both partners in the travel advisory with New York, have issued similar guidance regarding their neighboring states. On Tuesday, Gov. Philip D. Murphy of New Jersey said travelers from Massachusetts — which does not border his state — would be subject to the quarantine advisory; those from Delaware, which does, would not.

New Jersey has also called its advisory “voluntary,” while Connecticut and New York have threatened fines against those who violate their state’s orders. Connecticut has also allowed for travelers to provide a negative test result instead of quarantining.

On Tuesday, Gov. Ned Lamont of Connecticut revised an earlier executive order that limited entry from states that have high positivity rates, exempting those from New York, New Jersey and Rhode Island.

Mr. Cuomo also announced that California would return to the list of states under the travel advisory; it had previously been removed on Sept. 15. As of Tuesday, 41 states and U.S. territories are on New York’s travel advisory.

A clinical trial for antibody tests at Keele University in Britain earlier this year. The number of people with antibodies fell, researchers reported Monday, but experts said concern was overblown. 
Credit…Carl Recine/Reuters

The number of people in Britain with detectable antibodies to the coronavirus fell by roughly 27 percent over a period of three months, researchers reported Monday, prompting fears that immunity to the virus is short-lived.

But several experts said these worries were overblown. “Some of these headlines are silly,” said Scott Hensley, an immunologist at the University of Pennsylvania.

A decline in antibody levels after the initial illness does not necessarily indicate waning immunity to the virus, he said.

Declining antibody levels after the acute infection has resolved “is the sign of a normal healthy immune response,” Dr. Hensley said. “It doesn’t mean that those people no longer have antibodies, it doesn’t mean that they don’t have protection.”

The British report is based on three rounds of antibody tests carried out in 350,000 people between June 20 and Sept. 28. The participants tested themselves at home for antibodies using finger-prick assays that deliver a yes-or-no response, much like pregnancy tests. The results have not yet been vetted by scientific review.

Over the three-month period, the proportion of people with detectable antibodies in their blood dropped to 4.4 percent from 6 percent, the researchers reported. About 30 percent of the participants with positive results did not have any Covid symptoms.

Antibodies represent only one arm of the immune response, albeit the one that can most easily be measured. There are other branches of the immune system that can fend off illness, experts said, so antibody levels don’t present the full picture.

SUNY Oneonta Campus.
Credit…Cindy Schultz for The New York Times

Students at all State University of New York colleges and universities must test negative for the virus before leaving campus for Thanksgiving break, officials announced Tuesday, or they could face possible suspension.

The new policy, which applies to all students who take at least one in-person class, use on-campus services or work on campus, is meant to prevent students from spreading the virus to their contacts across the country. But details for how the policy will play out are scant as SUNY waits for colleges to submit their plans.

SUNY’s 64 colleges and universities have until Nov. 5 to submit plans to test about 140,000 students over a 10-day period before Thanksgiving break begins. Students who do not abide by state public health rules or SUNY policies may face suspension, said SUNY spokeswoman Holly Liapis.

“By requiring all students to test negative before leaving, we are implementing a smart, sensible policy that protects students’ families and hometown communities and drastically reduces the chances of Covid-19 community spread,” said SUNY Chancellor Jim Malatras in a statement.

Most SUNY colleges had already planned to shift to all online classes for the remainder of the semester after Thanksgiving. Since the fall semester began, SUNY has tested more than 270,000 students with a positivity rate of 0.52 percent, according to the statement. Many colleges will use “pool testing,” where a number of saliva samples are grouped together in a “pool” and tested as one, for the 10-day period, Ms. Liapis said.

SUNY officials had been implementing stricter testing guidelines, like mandatory surveillance testing, after an outbreak at SUNY Oneonta infected more than 700 students since late August. In-person classes were shut down for the fall, and the college president resigned in October.

“Campuses have been testing regularly, and cases have been low,” Ms. Liapis said. “We will work to make sure they’re tested before they can go home.”

Campuses have been keeping track of students as they get tested throughout the semester, and any student who does not comply with the new policy would be caught and penalized, Mr. Malatras said in an interview. He added that most students are cooperative and many would like to know their status before returning home.

“Most want to do the right thing,” he said.

Mayor Claudia Sheinbaum of Mexico City in August. Ms. Sheinbaum announced on Twitter that she had tested positive for the virus. 
Credit…Meghan Dhaliwal for The New York Times

The mayor of Mexico City has tested positive for the coronavirus, becoming the most high-profile politician in Mexico to contract the virus as the country struggles to contain a rise in new cases.

In a tweet posted Tuesday, the mayor, Claudia Sheinbaum, said she did not have symptoms, felt “strong” and would continue to “coordinate all activities from a distance, with the same commitment as usual.”

Mexico’s dense capital — the center of its pandemic — has been grappling with a recent surge in hospitalizations, which had been declining even after much of the city reopened in July following a lockdown. It is among several Mexican cities awash in new cases, including Juárez, where local officials recently declared a state of emergency and forced businesses to suspend operations to contain the outbreak.

There have been close to 900,000 confirmed cases in Mexico and more than 89,000 deaths, figures that the government has said underestimate the true toll of the virus in a country where testing remains relatively scarce.

Ms. Sheinbaum is closely allied with the president, Andrés Manuel López Obrador, who has downplayed the virus, questioned mask-wearing and kept testing low. But the mayor, a scientist by training, has diverged from the federal government, pushing more widespread testing and contact tracing and requiring face coverings on public transportation.

Earlier this year, when a member of her staff tested positive for the virus, Ms. Sheinbaum grew so concerned about whether she might have contracted it that she bought an oximeter and began testing herself multiple times per day.

A sign outside the football stadium at the University of Arkansas in Fayetteville encouraged safety precautions. 
Credit…Brett Rojo/USA Today Sports, via Reuters

Seven state legislators, all Republicans, have tested positive for the coronavirus in the last week in Arkansas, where daily case reports and hospitalizations are soaring to record levels.

In a sign of just how pervasive community spread of the disease has become in Arkansas, the state surgeon general, Dr. Gregory Bledsoe, announced on Twitter Monday night that the virus had penetrated his family from two directions.

His mother, State Senator Cecile Bledsoe, and his father have tested positive in connection with her work in the legislature, he said — and independently, his wife and two of his three children have the virus as well. “Just coincidence,” he wrote.

Dr. Bledsoe said he did not believe the infections were related to his medical work, either, because he has tested negative and has no symptoms.

Another lawmaker in the cluster is Representative Charlene Fite, who announced her positive test on Saturday. “Usually the final days of a campaign are busy and exciting,” she wrote in a Facebook post. “That will not be the case this time.”

In an email to The New York Times on Tuesday, Ms. Fite said she was feeling “much better.”

Senator Missy Thomas Irvin, the fourth of the seven lawmakers to test positive, also said she is feeling better.

“I felt like a train ran over me with the body and back aches,” she said in an email to the Times. “I still have head and chest congestion and I’m super tired, but I’m definitely over the hard part!”

The legislators kept in touch in a group chat, where they exchanged health tips and cheered each other up, she said.

One of the seven is a retired doctor, Joe A. Cloud, who represents Russellville in the state’s House of Representatives. He was released Tuesday morning after five days in the hospital.

Dr. Cloud said he believed he caught the virus during budget committee meetings in Little Rock on Oct. 13, 14 and 15. He wore a mask, he said, and so had “most” others. But he started feeling unwell afterward, tested positive on Oct. 18 and was later hospitalized when his oxygen levels dropped to dangerous levels.

“It’s a virus, it’s a billionth of our size, and unless somebody just completely isolates themselves, unfortunately you’re going to have some exposure,” Dr. Cloud said in an interview. His condition has improved, he said, but he still had a bad cough, and “it’ll be a couple of months before I can say I’m 100 percent.”

Senator Terry Rice and Representatives Michelle Gray and Stu Smith have also tested positive, according to legislative leaders.

Although the Senate canceled meetings last week after the first wave of cases, both houses are going ahead with committee meetings set for this week. Dr. Cloud said he would participate — virtually.

Budget hearings resumed Tuesday morning with distanced seating and remote-voting options under a new rule adopted last week, said Cecillea Pond-Mayo, a House spokeswoman. Plexiglass partitions and a mask requirement were already in place, she said.

Arkansas reported at least 21 new coronavirus deaths and 612 new cases on Monday, and has averaged 1,019 cases a day over the last week, 18 percent more than two weeks ago. Since the pandemic began, the state has reported at least 106,727 cases and 1,833 deaths, according to a New York Times database.

“We’re definitely seeing an uptick in our state, unfortunately,” Dr. Cloud said. “Try to be as absolutely careful as you can. Don’t hesitate to seek medical care.”

Esmeralda County, Nev., is one of only three counties in the United States that has not yet reported a coronavirus case. Karie Burham took orders in the diner she owns in Goldfield, the county seat. 
Credit…Ed Komenda/The Reno Gazette-Journal, via Associated Press

The coronavirus has spread everywhere in the United States.

Almost everywhere, that is.

Every county in America has reported at least one case of Covid-19 — except for some of the smallest and most far-flung places in Texas, Nevada and Hawaii. The reach of the virus into rural and urban counties alike shows how the pandemic, once concentrated in metropolitan hot spots, has now left few of even the most remote communities untouched as a third surge of infections has firmly taken hold.

Only three counties in the 50 states have never reported a Covid-19 case, according to a New York Times database — Esmeralda, Nev.; Loving, Texas; and Kalawao, Hawaii, a former leper colony on the island of Molokai. (County-level data is not available in some parts of Alaska.)

Two of those are the least populous counties in the nation: Kalawao, with 86 residents according to 2019 census estimates, and Loving with 169.

Exactly why these places haven’t had a confirmed case yet is hard to say. But they share some traits: They are sparsely populated, and fairly remote.

Some residents have come up with elaborate theories. In Esmeralda County — a rugged mining area with 873 residents in southwest Nevada between Las Vegas and Reno — a courthouse worker told The Reno Gazette Journal that it must have something to do with the local water, and particularly the arsenic in it.

Others said it was simply a matter of geography and chance.

“I guess we’ve just been lucky,” said Alan Haley, 64, a Loving County rancher who does not wear a mask in his daily travels. “It doesn’t really surprise me. Most of us, we haven’t really let it spook us too damn much.”

Loving County is in the flat West Texas desert near the New Mexico state line, about a 90-minute drive west of Odessa. The county seat, Mentone, has everything people expect in a small oil-country town — everything except a stoplight. Workers headed to and from the oil fields clog Highway 302 and give it a daytime bustle. The county executive, Skeet Lee Jones, has been known to keep a pistol in a desk drawer in his office.

In Hawaii, Kalawao County is so remote that for many years it was connected to the rest of Molokai island only by a steep mule trail. It ceased being a quarantine area once effective treatments for Hansen’s disease (leprosy) became available in the 1960s, but no new permanent residents are allowed and visits are strictly limited.

And yet even counties with zero cases know the upheaval and anxiety of the virus. Some people in and near Esmeralda and Loving counties wear masks, and have relatives, friends and classmates in other counties who have tested positive.

“It’s out there, and we’re doing everything that we can at school to keep the kids protected,” said Scotty Carman, the superintendent of the Wink-Loving Independent School District, which serves students from both Loving and neighboring Winkler County, which has reported 146 coronavirus cases so far. “We’re under a mask mandate above third grade,” Mr. Carman said, “so we’re trying to make sure kids are in compliance with that. It’s something we’re learning to deal with.”

Senator Mitch McConnell, the majority leader, has urged the White House not to strike a deal on coronavirus relief before the election.
Credit…Anna Moneymaker for The New York Times

What little hope Americans had remaining that they would get a needed coronavirus relief package before the election was dashed late Monday when Mitch McConnell, the majority leader, adjourned the Senate for two weeks after its vote to confirm Judge Amy Coney Barrett to the Supreme Court.

Already stalled for three months, prospects for a deal had largely faded, with Democrats, Senate Republicans and President Trump’s negotiators unable to come together on a deal to help keep struggling Americans afloat.

The first round of stimulus, which included beefed-up unemployment benefits, support to small businesses and $1,200 checks to individuals, was considered largely successful in staving off a worse economic calamity in the spring, with tens of millions of Americans relying on it to pay their bills, avoid evictions and keep their businesses running.

In a poll conducted this month by The New York Times and Siena College, a majority of likely voters said they supported a new $2 trillion stimulus package, while economists and the chair of the Federal Reserve have said an infusion of federal money would fuel an economic recovery now on shaky ground.

Mr. Trump abruptly pulled the plug on the talks early this month, only to reverse course in recent weeks. Without offering specifics, Mr. Trump said he had instructed Treasury Secretary Steven Mnuchin to “go big or go home.”

That statement put him at odds with Mr. McConnell, who cautioned the president against striking a deal with House Democrats.

Senate Republicans did not want to spend more than $500 billion.

Speaker Nancy Pelosi spoke with Mr. Mnuchin for nearly an hour on Monday but failed to reach a deal, her deputy chief of staff, Drew Hammill, wrote on Twitter.

While both the House and Senate can be called back for a vote with 24 hours notice, that appeared unlikely with Election Day less than a week away.

The Senate will reconvene on Nov. 9 and could take up negotiations again.

But by then, the backdrop could be vastly different, depending on what happens on Election Day.

Deb Grabo, a registered nurse, at a drive-through coronavirus testing site in Bismarck, N.D., on Monday.
Credit…Bing Guan/Reuters

The United States reported more than 74,300 new cases of the coronavirus on Monday, pushing the country’s daily average over the past week above 71,000, the most in any seven-day stretch of the pandemic.

Across the country, the outlook continues to worsen. More than 20 states are reporting case numbers at or near record levels. Bars and restaurants are facing new limits. In a handful of places, business curfews have been ordered or field hospitals have opened.

“There seems to be a Covid storm on the rise, and we have to get prepared,” said Gov. J.B. Pritzker of Illinois, who has imposed new restrictions on businesses in much of the state as cases have surged to record levels.

On a per-capita basis, the Upper Midwest and Mountain West continue to face the worst of the latest surge. A field hospital at the Wisconsin state fairgrounds has started accepting patients. Idaho is averaging around 900 cases each day, up from about 260 in mid-September. Five percent of all North Dakotans have now tested positive for the virus, the highest rate of any state.

Dr. Deborah L. Birx, the White House coronavirus response coordinator, visited North Dakota on Monday and warned that “there’s a whole other set of cases underneath those cases, of asymptomatic young people who are still getting together, or even 40-, 50- and 60-year-olds who I saw throughout Bismarck not wearing masks and not physically distancing yet being indoors.”

But it is not just the Northern Plains and rural West struggling. Pennsylvania set a single-day case record on Monday with 2,492 new cases. And North Carolina has reported a record number of coronavirus deaths in the past week.

All nonessential businesses in Newark, N.J., will have to close at 8 p.m. beginning Tuesday, city officials announced. As of Sunday, the deaths of 672 Newark residents had been linked to Covid-19, the disease caused by the virus, and the three-day average citywide positivity rate was 11.2 percent, more than double the statewide rate for the same period, the city said Monday.

Newark is the first municipality in New Jersey to adopt new, targeted shutdown measures, which come as the number of virus cases is increasing across the state. As of Monday, New Jersey has had an average of 1,211 new cases every day for the past week, an increase of 57 percent from the average two weeks earlier, according to a New York Times database.

Texas has overtaken California as the state that has recorded the most cases, with at least 916,000 since the pandemic began and a per capita case rate that ranks 17th in the nation. Its seven-day average of new cases is about 6,100, far below its July peak of over 10,000 but climbing sharply.

In El Paso, the number of people hospitalized with Covid-19 has more than tripled over the past three weeks, leading local officials to take drastic action, including the imposition of a two-week stay-at-home order and a 10 p.m. to 5 a.m. curfew that took effect Sunday.

To accommodate the increasing demand for inpatient care, officials are scrambling to make space for them by setting up overflow beds in a convention center and under tents in parking lots and by flying patients to medical centers outside the area.

A sharp rise in coronavirus infections has also strained hospitals across Idaho, leading Gov. Brad Little to restore some statewide restrictions to limit the spread of the virus on Monday. The state, he said, had reached a tipping point that required the limitation of gatherings and enforced wearing of masks at long-term care facilities.

The governor continued to resist a statewide mask mandate, saying he wanted mask-wearing rules to be determined by local officials, and he called for people to take personal responsibility. Idaho has averaged almost 900 new coronavirus cases per day over the past week, more than triple the numbers seen in early September.

In Wyoming, officials reported 436 new cases and nine new deaths on Monday. Both were single-day records for the state.