North Korea’s leader, Kim Jong-un, said that lapses in his country’s anti-pandemic campaign have caused a “great crisis” that threatened “grave consequences,” state media reported on Wednesday.

Mr. Kim did not clarify whether he was referring to an outbreak in North Korea, where the authorities had said there were no cases of the virus. But state media reported that the matter was serious enough for Mr. Kim to convene a meeting of the Political Bureau of his ruling Workers’ Party on Tuesday, during which Mr. Kim reshuffled the top party leadership.

Senior officials neglected implementing antivirus measures and had created “a great crisis in ensuring the security of the state and safety of the people,” Mr. Kim said.

Mr. Kim also berated party officials for their “ignorance, disability and irresponsibility,” said the official Korean Central News Agency.

A report said there would be some “legal” consequences for the officials.

The news agency said that some members of the Politburo and its Presidium, as well as some Workers’ Party secretaries, were replaced. In North Korea, all power is concentrated in the leadership of Mr. Kim, and he frequently reshuffles party officials and military leaders, holding them responsible for policy failures.

The North claims officially to be free of the virus, although outside experts remain skeptical, citing the country’s threadbare public health system and lack of extensive testing.

Still, North Korea has enforced harsh restrictions to contain transmission.

Last year, it created a buffer zone along the border with China, issuing a shoot-to-kill order to stop unauthorized crossings, according to South Korean and U.S. officials. South Korean lawmakers briefed by their government’s National Intelligence Service last year have said that North Korea executed an official for violating a trade ban imposed to fight the virus.

Last July, when a man from South Korea defected to the North, North Korea declared a national emergency for fear he might have brought the virus.

But Mr. Kim has also shown confidence that at least his inner circles were virus-free, sometimes presiding over meetings of party elites where no one wore masks.

During the meeting on Tuesday, Mr. Kim urged party officials to double down on his efforts to build a “self-reliant” economy. As North Korea’s economy has been hit hard by the pandemic, Mr. Kim has acknowledged that his five-year plan for growth had failed and instructed his officials to wage an “arduous march” through difficult economic times. This month, he warned of a looming food shortage.

The party meeting on Tuesday “suggests that the situation in the country has worsened beyond the capacity of self-reliance,” said Leif-Eric Easley, an associate professor of international studies at Ewha Womans University in Seoul.

“Pyongyang may be setting up a domestic political narrative to allow the acceptance of foreign vaccines and pandemic assistance,” he said. “Kim is likely to blame scapegoats for this incident, purging disloyal government officials and replacing them with others considered more capable.”

The coronavirus has reversed a steady rise in life expectancy in Brazil, with an estimated decline of 1.3 years in 2020 and an even more accelerated drop during the first months of 2021, according to a new report published in the journal Nature Medicine.

Significant, abrupt declines in life expectancy are rare and Brazil’s represents a major blow given the strides the country had made in improving health outcomes in recent decades, said Marcia Castro, the chair of the Department of Global Health and Population at Harvard, the lead author of the study.

“We expect declines of this magnitude when you have a major shock that leads to high mortality, like a war or a pandemic,” she said.

Brazil has reported more than 514,000 deaths from Covid-19, an official death toll surpassed only by that in the United States, which has lost more than 604,000 people. Even so, the United States, which has a considerably larger population, experienced a slightly lower life-expectancy drop last year: 1.13 years.

The pandemic has continued to steadily worsen in Brazil, where vaccinations have lagged. At least 18 million Brazilians have been infected so far, or at least one in 11 people, and the country is averaging over 65,000 new reported cases and over 1,600 deaths a day, according to official data. But, as in India, which has the world’s third-largest official death toll, many experts believe the numbers understate the true scope of the country’s epidemic. So far, about a third of Brazil’s population has had at least one shot of a vaccine, according to Our World in Data.

The decline in life expectancy is a jarring setback for Brazil, Latin America’s largest nation, which has spent billions of dollars in recent decades to expand the reach and quality of its universal public health care system.

Between 1945 and 2020, life expectancy in Brazil increased from 45.5 years to 76.7 years, an average of about five months per year. The setbacks of the Covid-19 era have reverted the country to 2014 levels, according to the study.

Brazil experienced a second wave of coronavirus cases in the first few months of this year that has been far deadlier than the first one, which receded at the end of 2020.

Dr. Castro and fellow researchers estimated that the resulting decline in life expectancy for 2021, based on the death toll recorded in the first four months of the year, will be about 1.78 years.

States in the Amazon region — including Amazonas, Rondônia, Roraima and Mato Grosso — experienced the steepest declines in life expectancy last year. Dr. Castro said states in the northeast, where governors imposed relatively strict quarantine measures, experienced lower drops.

Dr. Castro said Brazil’s life expectancy rate was likely to decline even more as the virus continued to kill hundreds of people each day, many of whom are relatively young. The average daily death toll for the past week was 1,610, according to a New York Times tracker.

“The decline in 2021 is going to be just horrible,” Dr. Castro said. “We are now losing even younger people.”

Last week, health officials announced that the Delta variant was responsible for about one in every five Covid-19 cases in the United States, and that its prevalence had doubled in the last two weeks.

First identified in India, Delta is one of several “variants of concern,” as designated by the Centers for Disease Control and Prevention and the World Health Organization. It has spread rapidly through India and Britain and poses a particular threat in places where vaccination rates remain low.

Here are answers to some common questions.

Does the Delta variant cause different symptoms?

It’s not clear yet. “We’re hurting for good data,” said Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.

But some evidence of a potential shift is emerging in Britain, where Delta has become the dominant variant.

“What we’ve noticed is the last month, we’re seeing different sets of symptoms than we were seeing in January,” said Tim Spector, a genetic epidemiologist at King’s College London, who leads the Covid Symptom Study, which asks people with the disease to report their symptoms in an app.

Headaches, a sore throat, and a runny nose are now among those mentioned most frequently, Dr. Spector said, with fever, cough and loss of smell less common.

These findings, however, have not yet been published in a scientific journal, and some scientists remain unconvinced that the symptom profile has truly changed. The severity of Covid, regardless of the variant, can vary wildly from one person to another.

If I’m vaccinated, do I need to worry?

Although there is not yet good data on how all of the vaccines hold up against Delta, several widely used shots, including those made by Pfizer, Moderna and AstraZeneca, appear to retain most of their effectiveness against the Delta variant, research suggests.

“If you’re fully vaccinated, I would largely not worry about it,” said Dr. Ashish K. Jha, dean of the Brown University School of Public Health.

Pockets of unvaccinated people, however, may be vulnerable to outbreaks in the coming months, scientists said.

“When you have such a low level of vaccination superimposed upon a variant that has a high degree of efficiency of spread, what you are going to see among under-vaccinated regions, be that states, cities or counties, you’re going to see these individual types of blips,” Dr. Anthony Fauci, the nation’s leading infectious disease expert, said on CNN on Tuesday. “It’s almost like it’s going to be two Americas.”

President Vladimir V. Putin urged Russians to get vaccinated against the coronavirus on Wednesday — his most extensive comments on the matter yet — as his country scrambles to contain a vicious new wave of the illness.

Speaking at his annual televised call-in show, Mr. Putin spent the opening half-hour trying to convince Russians to get one of the country’s four domestically produced shots. It was the latest instance of a marked change in tone about the pandemic from Russian officials, who for months did little to push a vaccine-wary public to get immunized but are now starting to make vaccination mandatory for some groups.

“It’s dangerous, dangerous to your life,” Mr. Putin said of Covid-19. “The vaccine is not dangerous.”

Only 23 million Russians, or about 15 percent of the population, have received at least one vaccine dose, Mr. Putin said. Polls this year by the independent Levada Center showed that some 60 percent of Russians did not want to be vaccinated, even though the domestically produced Sputnik V vaccine is widely seen as safe and effective.

Analysts attribute Russians’ hesitancy to a widespread distrust of the authorities combined with a drumbeat of state television reports that described the coronavirus as either mostly defeated or not very dangerous to begin with.

Mr. Putin revealed that he himself had received the Sputnik V vaccine this year — the Kremlin had previously refused to specify which shot he had been given — and that he had experienced a brief fever after the second dose.

He spoke just as his handling of the pandemic — long touted by the Kremlin as superior to the approach taken in the West — threatened to turn into a major debacle. Russia’s biggest cities, Moscow and St. Petersburg, have been reporting more than 100 deaths per day recently, setting records; nationwide, the number of reported new cases per day has doubled to more than 20,000 in recent weeks, with 669 deaths reported on Wednesday. The official toll is likely to be a significant undercount.

Regional officials in Moscow and elsewhere have resisted lockdowns. But, almost certainly with Mr. Putin’s blessing, they have made vaccination mandatory for large groups of people, such as service workers. That has prompted an outcry from many Kremlin critics and supporters alike.

“I don’t support mandatory vaccination, and continue to have this point of view,” Mr. Putin said, putting the responsibility for such orders on regional officials.

The renewed surge of the coronavirus could derail the Kremlin’s message of competence in comparison to Western dysfunction just as parliamentary elections approach in September. Mr. Putin’s most vocal opponents have already been jailed, exiled or barred from running, but obvious election fraud or a poor showing by his governing United Russia party could still weaken the president’s domestic authority.

In May, federal health officials in the United States said that fully vaccinated people no longer needed to mask up, even indoors. The advice set the stage for a national reopening that continues to gain momentum.

But that was before the spread of the Delta variant, a highly infectious form of the virus first detected in India and later identified in at least 85 countries. It now accounts for one in five infections in the United States.

Worried by a global surge in cases, the World Health Organization last week reiterated its longstanding recommendation that everyone wear masks.

On Monday, health officials in Los Angeles County followed suit, recommending that “everyone, regardless of vaccination status, wear masks indoors in public places as a precautionary measure.”

Barbara Ferrer, the county’s public health director, said the new recommendation was needed because of upticks in infections, a rise in cases due to the worrisome Delta variant, and persistently high numbers of unvaccinated residents, particularly children, Black and Latino residents and essential workers.

Roughly half of Los Angeles County residents are fully vaccinated, and about 60 percent have had at least one dose. While the number of positive tests is still below 1 percent in the county, the rate has been inching up, Dr. Ferrer added, and there has been a rise in the number of reinfections among residents who were infected before and did not get vaccinated.

To the extent that Los Angeles County has managed to control the pandemic, it has been because of a multilayered strategy that combined vaccinations with health restrictions aimed at curbing new infections, Dr. Ferrer said. Natural immunity among those already infected has also kept transmission low, she noted, but it is not clear how long natural immunity will last.

“We don’t want to return to lockdown or more disruptive mandates here,” Dr. Ferrer said. “We want to stay on the path we’re on right now, which is keeping community transmission really low.”

Health officials in Chicago and New York City indicated this week that they had no plans to revisit mask requirements. Officials at the Centers for Disease Control and Prevention declined to comment, but have also not signaled any intention to revise or re-examine masking recommendations for those who are fully vaccinated.

But the Delta variant’s trajectory outside the United States suggests that concerns are likely to intensify.

A rift has emerged between Australia’s federal government, state leaders and medical groups over vaccination advice, with several officials issuing public objections to Prime Minister Scott Morrison’s decision to make the AstraZeneca vaccine available to those under 40.

Australia’s vaccine advisory body has recommended that people under 60 should be vaccinated with the Pfizer shot because the AstraZeneca vaccine is associated with a very small risk of a serious blood-clotting disorder. But the country’s vaccination campaign was initially planned around AstraZeneca, and supplies of other shots are so far relatively constrained, with Pfizer appointments not yet open to most people under 40.

Less than 5 percent of Australians are fully vaccinated, and just under a quarter have had one dose of a vaccine. Parts of four states or territories, including four major cities, are in lockdown to halt outbreaks associated with the Delta variant, and there are restrictions in two more.

In response to outbreaks of the more infectious Delta variant of the virus, Mr. Morrison announced on Monday that the federal government would allow family doctors to administer the AstraZeneca vaccine to those under 40 who wanted it.

“If you wish to get the AstraZeneca vaccine, then we would encourage you to go and have that discussion” with your doctor, he said.

But soon after, state leaders spoke against the decision. “I do not want under-40s to get AstraZeneca,” Queensland’s chief health officer, Dr. Jeannette Young, said at a news conference on Wednesday. “I don’t want an 18-year-old in Queensland dying from a clotting illness who, if they got Covid, probably wouldn’t die.”

Parts of Queensland recently entered a three-day lockdown as authorities race to contain an outbreak.

The premier of Western Australia, Mark McGowan, echoed Dr. Young’s position and called for people over 60 to be given the Pfizer vaccine to combat vaccine hesitancy.

Dr. Omar Khorshid, president of the Australian Medical Association, which represents doctors and medical students, said the announcement “was a surprise.” While some medical clinics have started providing consultations to younger people wanting to get the AstraZeneca vaccine, some doctors have said they want more information before they would be comfortable doing so.

Until the pandemic shuttered all of its productions, “Hamilton” was making a lot of money: It has played to full houses since it opened in 2015, and on Broadway it has been seen by 2.6 million people and grossed $650 million.

So why is the show getting $30 million in relief from the federal government, with the possibility of another $20 million coming down the road?

The answer is that, before the pandemic, “Hamilton” had five separately incorporated productions running in the United States — one on Broadway and four on tour — and, under the rules set up for the government’s Shuttered Venue Operators Grant program, which provides pandemic relief for the culture sector and live-event businesses, each was eligible for $10 million to help make up for lost revenue.

“Remember when Chrysler and GM were about to go bankrupt? In the same way that the federal government came in to bail out auto companies, it’s doing the same thing for all of show business with this legislation,” said the show’s lead producer, Jeffrey Seller. “It’s returning us to health and it’s protecting the well-being of our employees.”

Seller said that none of the money would go to the show’s producers (including him) or its investors, and none would be used as royalties for artists (including the show’s creator, Lin-Manuel Miranda).

Instead, he said, the money will be used to remount the shuttered productions, and to reimburse the productions for pandemic-related expenses.

The rollout of the Shuttered Venue Operators Grant initiative, a $16 billion federal aid program designed to help get cultural organizations back on their feet after the pandemic forced many to close, has been plagued by delays and confusion. But the Small Business Administration, which is administering the program, has begun announcing grant recipients, and there are indications that Broadway and its affiliated businesses could fare well.

The Supreme Court on Tuesday refused to lift a moratorium on evictions that had been imposed by the Centers for Disease Control and Prevention in response to the coronavirus pandemic.

The vote was 5 to 4, with Chief Justice John G. Roberts Jr. and Justices Stephen G. Breyer, Sonia Sotomayor, Elena Kagan and Brett M. Kavanaugh in the majority.

The court gave no reasons for its ruling, which is typical when it acts on emergency applications. But Justice Kavanaugh issued a brief concurring opinion explaining that he had cast his vote reluctantly and had taken account of the impending expiration of the moratorium.

“The Centers for Disease Control and Prevention exceeded its existing statutory authority by issuing a nationwide eviction moratorium,” Justice Kavanaugh wrote. “Because the C.D.C. plans to end the moratorium in only a few weeks, on July 31, and because those few weeks will allow for additional and more orderly distribution of the congressionally appropriated rental assistance funds, I vote at this time to deny the application” that had been filed by landlords, real estate companies and trade associations.

He added that the agency might not extend the moratorium on its own. “In my view,” Justice Kavanaugh wrote, “clear and specific congressional authorization (via new legislation) would be necessary for the C.D.C. to extend the moratorium past July 31.”

At the beginning of the pandemic, Congress declared a moratorium on evictions, which lapsed last July. The C.D.C. then issued a series of its own moratoriums.

“In doing so,” the challengers told the justices, “the C.D.C. shifted the pandemic’s financial burdens from the nation’s 30 to 40 million renters to its 10 to 11 million landlords — most of whom, like applicants, are individuals and small businesses — resulting in over $13 billion in unpaid rent per month.” The total cost to the nation’s landlords, they wrote, could approach $200 billion.

The moratorium defers but does not cancel the obligation to pay rent; the challengers wrote that this “massive wealth transfer” would “never be fully undone.” Many renters, they wrote, will be unable to pay what they owe. “In reality,” they wrote, “the eviction moratorium has become an instrument of economic policy rather than of disease control.”

In urging the Supreme Court to leave the moratorium in place, the government said that continued vigilance against the spread of the coronavirus was needed and noted that Congress had appropriated tens of billions of dollars to pay for rent arrears.