Most colleges appear to be trying to sway students with warnings and pleas, and relying on peer pressure to moderate behavior, but some are taking a more punitive approach. Purdue University suspended 36 students after a cooperative house was caught partying less than 24 hours after the university president outlawed off-campus parties. At the University of Connecticut, several students were evicted from campus housing over a mask-free dorm bash.

The Northeastern students have the right to contest the action in an “expedited hearing,” the university said.

They were enrolled in a program that normally offers international experiences for first-year students, but some were placed in Boston this fall because of the pandemic.

The dismissed students will not be allowed to attend fall classes remotely, said the spokeswoman, Ms. Nyul, and they must start over as first-year enrollees if they come back.

They were notified on Friday that they would have to vacate the hotel within 24 hours, the university said, and before leaving, would have to be tested for the coronavirus at Northeastern. Anyone who tested positive would be moved into “wellness housing” at the university until they no longer had the virus.

Northeastern said that all students in the program had been forewarned of the obligation to practice social distancing and wear masks when among others. “Students who attend an unsafe gathering, social or party, either on or off-campus, can expect suspension,” Madeleine Estabrook, senior vice chancellor for student affairs, wrote in a letter to students.

In a letter to members of the U.N.’s Security Council, the official, Mark Lowcock, the under secretary general for humanitarian affairs, said the risk of famines in these areas had been intensified by “natural disasters, economic shocks and public-health crises, all compounded by the Covid-19 pandemic.” Together, he said, “these factors are endangering the lives of millions of women, men and children.”

The letter, which has not been made public, was conveyed by Mr. Lowcock’s office to the Security Council on Friday under its 2018 resolution requiring updates when there is a “risk of conflict-induced famine and widespread food insecurity.” A copy of the letter was seen by The New York Times.

United Nations officials have said before that all four areas are vulnerable to food deprivation because of chronic armed conflicts, and the inability of humanitarian relief providers to freely distribute aid. But the added complications created by the pandemic have now pushed them closer to famine conditions.

Mr. Lowcock’s new warning of impending famines effectively escalates those alerts. Under a monitoring system for assessing hunger emergencies, famine is Phase 5, the worst, marked by “starvation, death, destitution and extremely critical acute malnutrition levels.”

The lockdown, which began in early August and had been set to end on Sept. 13, will now last until at least Sept. 28, said Dan Andrews, premier of the state of Victoria. Expert modeling, he said, suggests that easing restrictions too quickly could lead to a new wave of infections and keep the state from reaching its goal of lifting almost all restrictions by the end of the year.

The announcement came a day after about 200 protesters in Melbourne clashed with the police at a “Freedom Day” rally calling for an end to pandemic restrictions. The police arrested 17 protesters and fined more than 160 others — nearly everyone who had flouted the authorities’ instructions to stay home.

Tensions have surged in the fifth week of Victoria’s lockdown, which is one of the strictest in the world. All nonessential businesses are closed. Melburnians are allowed to leave the house only for work, exercise or buying groceries, and travel is restricted to within about three miles of home.

Under the changes Mr. Andrews announced on Sunday, after Sept. 13 the nightly curfew will begin at 9 p.m. instead of 8 p.m., outdoor exercise will be limited to two hours a day instead of one, and people living on their own will be allowed to have one friend or family member in their home whereas currently they can meet only with intimate partners. If the average daily rise in cases falls below 50 by Sept. 28, Melbourne will move on to the next stage of reopening.

Restrictions in the rest of Victoria, which is under a less severe lockdown, will be eased slightly after Sept. 13.

In other coronavirus news from around the world:

Their statement, which has not been finalized, is expected to say that the companies will not release any vaccines that do not follow rigorous efficacy and safety standards, according to representatives of three of the companies.

The joint statement was planned for early next week, but it may be released earlier since its existence was made public on Friday by The Wall Street Journal. The manufacturers that are said to have signed the letter include Pfizer, Moderna, Johnson & Johnson, GlaxoSmithKline and Sanofi.

Pfizer and Moderna, along with the British-based company AstraZeneca, are testing their candidates in late-stage clinical trials. Pfizer’s chief executive said this week that the company could see results as early as October, but the others have said only that they plan to release a vaccine by the end of the year.

Contagion operates on a simple rule: The more infections there are in an open population, the more opportunities it has to spread until enough people are protected either by immunity or a vaccine.

So elected officials and public health experts worry that active coronavirus infections in the United States during the Labor Day weekend are roughly twice what they were at Memorial Day. Roughly a month after holiday gatherings at the end of May, the country’s seven-day average of new daily cases had shot up to the highest level so far, more than 60,000.

The virus’s spread is broad, so few hospitals are overwhelmed the way many were in New York, New Jersey and other areas that were hit hard in the spring. And more treatments are available. Over all, fewer Americans are sick, hospitalized or dying from Covid-19 than in the spring or summer surges.

However, deaths are trending up in at least 12 states, according to a New York Times database: Arkansas, Alabama, West Virginia, Kentucky, Missouri, Hawaii, Virginia, Montana, Illinois, Kansas, Maryland and Colorado. North Carolina appears to be joining that group, reporting 45 deaths — a record for the state — on Saturday. Almost all of those states also have caseloads that were already high or trending upward.

On Saturday, officials in West Virginia announced more than 250 new cases, its third-highest daily total. The state has now announced more cases over the last week than in any other seven-day period.

The top-seeded women’s doubles team at the United States Open tennis tournament was forced to withdraw from the event this weekend as the rules for players exposed to the virus changed for the third time in less than a week, and the second time in 24 hours.

The team’s Saturday match was removed from the schedule, even though the day before a match that included another player who had been exposed to the virus was allowed to take place, albeit after a delay of about two and a half hours to consider the rule change.

“This probably cost us a Grand Slam,” Michael Joyce, Ms. Babos’s coach, said of the forced withdrawal of a pair that had already won three major doubles titles together — the 2018 and 2020 Australian Open and the 2019 French Open.

Two days before the tournament began, Benoît Paire of France tested positive for the coronavirus. Mr. Paire was removed from play, but rules about the people in contact with him shifted over time.

Electronic contact tracing revealed that Mr. Paire had been in close contact for an extended period — in a card game at one of the two hotels housing players on Long Island and possibly through other socializing — with seven players, including Ms. Mladenovic, also of France.

After Mr. Paire’s positive test, U.S. Tennis Association officials scrambled to create a revised set of procedures for players who had been exposed but then tested negative, including daily screening and isolation from the rest of the players. The exposed players would be required to confine themselves to their hotel rooms unless traveling to the tournament’s site, the Billie Jean King National Tennis Center in Queens.

Under those rules, Ms. Mladenovic had remained in the tournament, though after a stunning collapse in her second-round singles match, she vented frustration over her confinement.

China’s push is complex, with intelligence officials focusing on universities in part because they view the institutions’ data protections as less robust than those of pharmaceutical companies. Its operatives have also surreptitiously used information from the World Health Organization to guide its vaccine hacking attempts, both in the United States and Europe, according to a current and a former official familiar with the intelligence.

To date, no corporation or university has announced any data breaches resulting from the publicly identified hacking efforts. But some of the operations succeeded in at least penetrating defenses to get inside computer networks, according to one American government official.

“We never thought, ‘Hey, we’re never going to get on that court together again as a team,’” said Ms. Hower, 68, who attended the school, like her father and granddaughters.

About 150 Catholic schools have closed, said Kathy Mears, the director of the National Catholic Educational Association, equal to about 2 percent of the 6,183 schools that were up and running last year. The number of closures is at least 50 percent higher this year than in previous years, she said.

As parents and families lost their jobs during the pandemic, many could no longer pay tuition at Catholic schools. And when churches began shutting down to curb the spread of the virus, that also ended a major source of donations — some of which would normally be allotted for parish schools.

Among the best-known Catholic schools shutting its doors is the Institute of Notre Dame, an all-girls facility in Baltimore. Some alumni are fighting to keep the school open, upset that school leaders haven’t pushed harder to avoid closure.

Drena Fertetta, an alumnus who graduated from Notre Dame in 1983, began a group dedicated to reopening the school next year, perhaps at a different site.

“There is just a sisterhood that happens to the girls who go to that school,” Ms. Fertetta said. “It’s not something we’re willing to just walk away from.”

A Maine wedding reception seeded over 100 infections. The three people who died weren’t among the guests.

Three deaths from Covid-19 and 147 infections have been linked to an August indoor wedding reception in north-central Maine, the spokesperson for the state’s Center for Disease Control and Prevention said on Saturday. None of those who died had attended the wedding, according to the C.D.C. spokesperson.

From the wedding in Millinocket, about 70 miles north of Bangor, transmission passed into a prison and a long-term care facility — both of which are more than 100 miles from the wedding venue.

As of Thursday, there were 144 cases associated with the wedding, said Nirav Shah, the director of Maine’s C.D.C. Of those cases, 56 were wedding guests and their second or tertiary contacts, Mr. Shah said at a briefing on Thursday.

A member of the York County jail staff who tested positive for the virus attended the wedding, Dr. Shah said. Now 18 additional staff members, 46 of the jail’s inmates and seven family members of staff have confirmed cases, Dr. Shah said.

The Maplecrest Rehabilitation and Living Center in Madison, about 100 miles away, has also been affected by cases linked to the wedding. A staff member at Maplecrest who is a secondary contact of one of the wedding guests tested positive, and as of Thursday there were 15 more infected individuals at the facility, Dr. Shah said. Eight of the cases are among residents, and seven among the staff.

Not so long ago, before the coronavirus, India’s future looked entirely different.

But the economic devastation caused by the pandemic is imperiling many of India’s aspirations. The country’s economy has shrunk faster than any other major nation’s. As many as 200 million people could slip back into poverty, according to some estimates. Many of its normally vibrant streets are empty, with people too frightened of the outbreak to venture far.

Much of this damage was caused by a lockdown imposed by Prime Minister Narendra Modi that experts now say was both too tight and too porous, both hurting the economy and spreading the virus. India now has the fastest-growing coronavirus outbreak, with more than 80,000 new infections reported each day. The country has now topped four million confirmed cases.

A sense of malaise is creeping over the nation. Its economic growth was slowing even before the pandemic. Social divisions are widening. Anti-Muslim feelings are on the rise, partly because of a malicious social media campaign that falsely blamed Muslims for spreading the virus. China is increasingly muscling into Indian territory.

Scholars use many of the same words when contemplating India today: Lost. Listless. Wounded. Rudderless. Unjust.