The Northeastern United States, devastated by the coronavirus in the spring and then held up as a model of infection control by the summer, is now seeing the first inklings of what might become a second wave of the virus.
The rise in case numbers has prompted state and local officials to reverse course, tightening restrictions on businesses, schools and outdoor spaces.
In Boston, plans to bring children back to school have been halted as cases climb precariously. New virus clusters are emerging in Connecticut, Maryland, Pennsylvania and Rhode Island. In New York City, the number of new cases each day now averages more than 500 for the first time since June, and the city is putting strict rules in place in some neighborhoods.
In New Jersey, where hospitalizations are on the rise and the rate of infection has almost doubled, towns have closed public parks and picnic areas to discourage people from gathering. Gov. Gina Raimondo of Rhode Island extended restaurant capacity rules for another month.
Michael Osterholm, an infectious diseases expert at the University of Minnesota, said that early in the nation’s outbreak, New York and much of the Northeast had successfully tamped down transmission of the virus with physical distancing and masking, as much of Europe had done.
“The point is, once you let up on the brake, then eventually, slowly, it comes back,” Dr. Osterholm said.
By many measures, the Northeast is still doing quite well, particularly compared with virus hot spots elsewhere in the country, including the Midwest and Great Plains.
Still, the number of people in the hospital — a clear measure of those most seriously affected by an outbreak — is starting to trend slightly upward again in the Northeast.
There may be a number of reasons for the upward trend in cases.
The air turned suddenly chilly in past few weeks, sending people who had been lounging in sunny parks indoors. Students returned to schools and college campuses.
But it may also be that Northeasterners, who were among the first to take the virus seriously, are simply growing weary.
“We’re all kind of exhausted with it,” said Danielle Ompad, an infectious-disease epidemiologist at New York University. “We have to acknowledge that this is not easy.”
The World Food Program, a United Nations agency, was awarded the Nobel Peace Prize on Friday for its efforts to combat hunger globally, the Nobel committee announced.
The organization was recognized for its work during a coronavirus pandemic that has “contributed to a strong upsurge in the number of victims of hunger in the world,” the committee said in a statement.
The United Nations body — the largest humanitarian organization addressing hunger and promoting food security internationally — last year provided assistance to nearly one million people in 88 countries.
But in many countries, particularly those wracked by war, the combination of conflict and the pandemic has sharply increased the numbers of people on the brink of starvation.
“In the face of the pandemic, the World Food Program has demonstrated an impressive ability to intensify its efforts,” the committee said.
President Trump announced on Thursday that he hoped to return to the campaign trail on Saturday, just nine days after he tested positive for the coronavirus.
In his first extended public comments since learning he had the virus last week, Mr. Trump balked at participating in a debate next Thursday with former Vice President Joseph R. Biden Jr. if it was held remotely as the organizers decided to do out of health concerns.
But Mr. Trump secured a statement from the White House physician clearing him to return to public activities on Saturday and then promptly said he would try to hold a campaign rally in Florida that day, two days earlier than the doctor had originally said was needed to determine whether he was truly out of danger.
The president again dismissed the virus, saying, “when you catch it, you get better,” ignoring the more than 212,000 people in the United States who did not get better and died from it.
In his statement on Thursday night, the physician, Dr. Sean P. Conley, reported that Mr. Trump “has responded extremely well to treatment” and that by Saturday, “I fully expect the president’s return to public engagement.” Dr. Conley, who has previously acknowledged providing the public with a rosy view of the president’s condition to satisfy his patient, contradicted his own timeline offered upon Mr. Trump’s release from the hospital, when he said doctors wanted to “get through to Monday.”
The president has not been seen in person since returning to the White House on Monday, but he sought to reassert himself on the public stage with a pair of telephone interviews with Fox News and Fox Business as well as a video and a series of Twitter messages.
In an interview on Fox Business, Mr. Trump again suggested that veterans and their families had spread the coronavirus at the White House, floating the idea that a meeting with the loved ones of fallen military members might have been the source of his own infection.
China said on Friday that it would join a multilateral effort to manufacture and distribute a coronavirus vaccine, portraying itself as a responsible global citizen dedicated to improving public health around the world.
The decision to join was “an important step China has taken to uphold the concept of a shared community of health for all and to honor its commitment to turn Covid-19 vaccines into a global public good,” Hua Chunying, a spokeswoman for the country’s Foreign Ministry, said in a statement.
The decision highlights how Beijing is positioning itself as an influential player in international diplomacy at a time when the United States has pulled back from its role as a global leader. Such moves could potentially help China push back against accusations that its ruling Communist Party should be held responsible for its initial missteps when the virus first emerged last year.
More than 160 countries have joined the international agreement known as Covax, which aim to ensure both rich and poor countries receive new coronavirus vaccines simultaneously.
The Trump administration said last month that it would not join Covax because it “will not be constrained by multilateral organizations influenced by the corrupt World Health Organization and China.”
For weeks, China, which has four vaccine candidates in late-stage clinical trials, had been reticent about whether it would participate in the group.
Ms. Hua said on Friday that the country had decided to join the vaccine agreement “even when China is leading the world with several vaccines in advanced stages of R&D and with ample production capacity.”
“We are taking this concrete step to ensure equitable distribution of vaccines, especially to developing countries, and hope more capable countries will also join and support Covax,” she added.
In other news around the world:
The health authorities in Sri Lanka ordered the closure of bars, restaurants, casinos, nightclubs and spas as they worked to contain a growing cluster of new virus infections, The Associated Press reported. The country reported its first locally transmitted case in more than two months last weekend, which led to the discovery of a cluster centered in a garment factory in densely populated Western Province, home to the capital, Colombo. By Friday the number of cases linked to the cluster had climbed to 1,053, with more than 2,000 more people asked to quarantine at home. Sri Lanka has reported 4,488 cases of the virus, and 13 deaths.
The 124th edition of the French Open was postponed four months by the pandemic and will end this weekend against the same backdrop, as infection rates rise quickly in France.
The controlled environment constructed by tournament officials to keep the participants safe is holding — but barely.
On Wednesday, the host country reported 18,746 new cases. That same day, the men’s No. 11 seed, David Goffin, who lost in the first round to Jannik Sinner, announced on Instagram that he had become the latest of a handful of participants to test positive for the virus.
The spike in infections in and around Paris led local government officials to place the city on maximum alert starting Tuesday, leading to the closure of all bars and gyms in the city. Restaurants have been allowed to stay open but with stricter health protocols, including social distancing, contact tracing and a closing time no later than 10 p.m.
“It’s hard to see these things unfold again after six months,” the men’s world No. 1 singles player, Novak Djokovic, said, alluding to the first lockdown, which lasted eight weeks in most of France. “It’s hard to believe that we’re going to go through that again.”
In other sports news:
For the second consecutive week, the N.F.L. has shuffled its schedule to accommodate teams that have had players and staff members who have tested positive for the coronavirus. The rescheduled games include one involving the Tennessee Titans, who have had the league’s worst outbreak, with nearly two dozen players, coaches and staff members testing positive.