Singapore, an early success story, is having a surge in cases, while European countries start to ease restrictions. Oil prices nosedived as a worldwide surplus grew.

This briefing has ended. Read the latest developments in the coronavirus pandemic here.

Turkey has surpassed China in its number of confirmed coronavirus cases, as the tally rose to more than 90,000 by Monday, with deaths reaching at least 2,140, according to official government figures. But the true death toll may be much higher.

Officers and relatives carried a coffin in a special area of a cemetery that the government opened for coronavirus cases in Istanbul in late March.

Data compiled by The New York Times from records of deaths in Istanbul indicate that Turkey is grappling with a far bigger calamity from the coronavirus than official figures and statements indicate. The city alone recorded about 2,100 more deaths than expected from March 9 to April 12, based on weekly averages from the last two years, far more than officials reported for the whole of Turkey during that time.

While not all those deaths are necessarily directly attributable to the coronavirus, the numbers indicate a striking jump in fatalities that has coincided with the onset of the outbreak, a preliminary indicator that is being used by researchers to cut through the fog of the pandemic and assess its full toll in real time.

The government maintains that it acted swiftly, stopping flights and border crossings from five of the most affected countries in February and closing schools, restaurants and bars in mid-March when the first case of infection was confirmed.

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But by then, the statistics compiled by The Times show, the damage was done. And medical professionals say that Turkey did not do enough to halt international travelers, and neglected contact tracing and community care.

“In February, they did nothing, although it was known the disease was there,” Dr. Sinan Adiyaman, head of the Turkish Medical Association, said in an interview.

The government announced its first death from Covid-19 on March 17. But the statistics compiled by The Times suggest that even around that time, the number of deaths overall in Istanbul was already considerably higher than historical averages, an indication that the virus had arrived several weeks earlier.

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Any death statistics in the midst of a pandemic are tricky to pin down and must be considered preliminary. Many European countries are engaged in trying to improve their death statistics, which they now acknowledge are incomplete.

COUNTING CASES Coronavirus cases have ballooned in Istanbul and Izmir, big cities with international business and tourism connections, amid questions about Turkey’s statistics.

There are many hurdles to developing and widely distributing a vaccine, a W.H.O. official warned.

Image Michael Ryan, left, head of the W.H.O.’s emergencies program, at a coronavirus briefing in March. Credit... Fabrice Coffrini/Agence France-Presse — Getty Images

The head of the World Health Organization’s emergencies program warned on Monday that even if a vaccine against the coronavirus were quickly developed, manufacturing and distributing it could prove extraordinarily difficult.

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There is no approved treatment for or vaccine against infection with the coronavirus. More than two dozen companies have announced vaccine programs; at least three candidates already are in human trials.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, has warned that a vaccine is at least 18 months away. Other experts say even that timeline is optimistic.

The development process is important, but manufacturers must begin planning to scale up manufacturing capacities to meet global demand when a successful vaccine is discovered, said Dr. Michael Ryan, head of the W.H.O.’s emergencies program.

Billions of people around the globe eventually may need vaccination. Modern vaccines, made with DNA and RNA, require specialized facilities; it is not clear who could make them.

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And it will be important that vaccines go where they are most needed, not simply to the countries that can afford them. The W.H.O. is working with government leaders and nonprofits like the Bill and Melinda Gates Foundation and the Coalition for Epidemic Preparedness Innovations to ensure that means for equitable vaccine distribution are in place when the time comes, Dr. Ryan said.

“We’ve worked for over 20 years trying to ensure that products like vaccines are distributed in emergencies on the basis of epidemiological need,” Dr. Ryan said at a news briefing. “We intend to do exactly the same here.”

The agency has a long history of distributing vaccines to countries in need, including the meningitis, yellow fever, cholera and polio vaccines. Yet mass vaccination campaigns are still logistically difficult and often met with resistance in the community.

“As a global health architecture, we’re not very good at delivering vaccines in people other than children — in adults,” Dr. Ryan said.

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“If this is to work, it will require one of the greatest scientific, one of the greatest political, one of the greatest financial, one of the greatest public health operations in a generation,” he added.

Germany cautiously restarts its economy, allowing small shops to open.

Chancellor Angela Merkel of Germany warned against reopening too quickly as the country moved to ease coronavirus restrictions. Credit... Image by Laetitia Vancon for The New York Times

Across Germany, smaller stores were allowed to open their doors on Monday for the first time in nearly a month, under initial measures to ease restrictions imposed in March as the coronavirus outbreak took hold. Germans are still required to stay at least five feet from one another at all times until the end of April.

“We must not allow ourselves to be lulled into a false sense of security,” Chancellor Angela Merkel said at a news conference on Monday, warning that the consequences of the new measures would be visible only in two weeks’ time. “That is what makes the situation so difficult.”

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Norway, the Czech Republic and Denmark, all lifted some restrictions on Monday, attempting to balance public health against economic revival. Across Europe, the confirmed coronavirus toll passed one million infections and 100,000 deaths, according to the European Center for Disease Control.

Rana Basar reopened her jewelry and accessories shop in the normally bustling Ottensen shopping district of Hamburg on Monday, but said it had been a quiet start.

“It is not like people are in the mood to go shopping,” she added.

She prepared her store, Junajoux, with disinfectant and markings on the floor to help the two to three customers allowed in at a time to keep the required distance, as well as a mask to wear when customers are present. One of the biggest challenges, she said, was organizing care for her two children, because schools remain closed.

“A lot of this has not been fully thought through,” Ms. Basar said.

In Rostock, where the local zoo was one of several in the country allowed to reopen, around 1,000 people — roughly half of normal numbers — were expected to visit the animals that could be viewed from outside, as indoor exhibits remained closed. All large gatherings have been banned until the end of summer.

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Germany has recorded 141,672 coronavirus cases, with 4,404 fatalities, but the rate of infection has been steadily slowing in recent days and the country’s health system has been able to cope with the strain.

WAY OUT Countries are closely watching as Germany goes about reopening its economy

The latest in science: Six feet between tables may not be enough distance to safely reopen restaurants.

Image An empty table at a restaurant in Dayton, Ohio, on March 15, the last day before bars and restaurants were closed in that state. Credit... Kyle Grillot for The New York Times

In January, at a restaurant in Guangzhou, China, one diner infected with the novel coronavirus but not yet feeling sick appeared to have spread the disease to nine other people. One of the restaurant’s air-conditioners apparently blew the virus particles around the dining room.

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There were 73 other diners who ate that day on the same floor of the five-story restaurant, and the good news is they did not become sick. Neither did the eight employees who were working on the floor at the time.

Chinese researchers described the incident in a paper that is to be published in the July issue of the Emerging Infectious Diseases, a journal published by the Centers for Disease Control and Prevention. The field study has limitations. The researchers, for example, did not perform experiments to simulate the airborne transmission.

That outbreak illustrates some of the challenges that restaurants will face when they try to reopen. Ventilation systems can create complex patterns of air flow and keep viruses aloft, so simply spacing tables six feet apart — the minimum distance that the C.D.C. advises you keep from other people — may not be sufficient to safeguard restaurant patrons.

The social nature of dining out could increase the risk. The longer people linger in a contaminated area, the more virus particles they would likely inhale. Eating is also one activity that cannot be accomplished while wearing a mask. Virus-laden droplets can be expelled into the air through breathing and talking, not just through coughs and sneezes.

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On the other hand, all of the people who became sick at the restaurant in China were either at the same table as the infected person or at one of two neighboring tables. The fact that people farther away remained healthy is a hopeful hint that the coronavirus is primarily transmitted through larger respiratory droplets, which fall out of the air more quickly than smaller droplets known as aerosols, which can float for hours.

AIR CURRENTS Read the full article on how the coronavirus spread in a restaurant in China.

Filipino nurses work the front lines in foreign lands.

Image Jhoanna Mariel Buendia, a nurse from the Philippines, at home in York, England. One of the nurses in her family has died in Florida, and another has been hospitalized in California. Credit... Mary Turner for The New York Times

Each year about 13,000 nurses leave the Philippines for jobs in wealthier countries, sending money back home, often living in bare-bones conditions, far from familiar places and people.

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Covid-19 has required them to make an additional sacrifice: risking their health and their lives by caring for the sick. In places with major coronavirus outbreaks, nurses and doctors working in hospitals have been among the people most likely to become infected.

The virus has killed at least seven Filipino employees of Britain’s National Health Service, and in the United States it has claimed the lives of at least five nurses and a doctor from the Philippines.

The threat is as real as can be to Jhoanna Mariel Buendia, 27, a nurse who treats Covid-19 patients in the intensive care unit of a hospital in York, England.

Last month, her aunt, Araceli Buendia Ilagan, 63, an associate supervisor in the cardiac surgical intensive care unit of a hospital in Miami, died of the disease. An uncle, a nurse in California, is hospitalized with the virus.

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Ms. Buendia is one of four nurses from the Philippines sharing a house in York.

“The common denominator is that we’re all scared,” she said.

Western countries rely heavily on health care workers from other parts of the world — about one-sixth of the nurses working in the United States are immigrants — and even with that recruitment, there are labor shortages. The Philippines produce particularly large numbers of nurses.

In response to the pandemic, the Philippine government has temporarily barred health workers from leaving the country, saying that going abroad would put them at risk, and that they were needed at home.

Coronavirus Schools Briefing: It’s back to school — or is it? Sign Up

AT RISK, FAR FROM HOME Thousands of Filipino nurses and other migrant health workers in Western countries find that the jobs they left home for pose a threat

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As new U.S. hotspots emerge and Washington stays at an impasse, governors grapple with reopening.

Image A first responder after checking on a patient in isolation who was experiencing worsening symptoms in Chelsea, Mass., on Friday. Credit... Scott Eisen/Getty Images

As Massachusetts and some prisons become hotspots of the coronavirus outbreak in the United States, President Trump and Democratic lawmakers remained deadlocked on Monday over a bill to keep paychecks flowing to small business employees.

More evidence emerged that New York, the hardest-hit state, had reached a plateau — a tragically high one — as Gov. Andrew M. Cuomo reported 478 more Covid-19 deaths, the lowest one-day figure in more than two weeks. (The state’s total of more than 14,000 deaths does not count what New York City says are 3,700 presumed Covid-19 deaths among people who were never tested for the virus.)

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In some parts of the country, the virus continues to spread quickly. Massachusetts now has the third-most confirmed infections of any state, with more than 38,000, and the fourth-most deaths, with more than 1,700.

A New York Times analysis shows that four of the country’s 10 largest sources of new infections are prisons or jails. An Ohio state prison is the biggest source, with 1,828 inmates and 103 employees infected.

More than 770,000 people nationwide have tested positive for the novel coronavirus and more than 37,000 have died, according to data collected by The Times — and experts say the true figures are likely much higher.

New York offered a small suggestion of good news on Monday, starting a program to test people for coronavirus antibodies. The accuracy of the testing remains in question, but if successful, it could indicate how many people have some immunity and who they are, which are important steps toward jumpstarting the economy.

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Singapore seemed to have coronavirus under control. Then cases doubled.

Image Migrant workers at a dormitory in Singapore this month. Credit... Ore Huiying for The New York Times

After recording its first coronavirus case on Jan. 23, Singapore did almost everything right.

The prosperous city-state traced the close contacts of every infected patient, shut the borders to populations likely to carry the contagion, and provided free testing and treatment.

But over the past few days, Singapore’s caseload has more than doubled, with more than 8,000 cases confirmed as of Monday, the highest in Southeast Asia. Most of the new infections are within crowded dormitories where low-paid migrant laborers from South Asia and China live, unnoticed by many of the country’s richer residents and, it turns out, the government itself.

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The group proved a major blind spot in the coronavirus pandemic, exposing the starkly different experiences of rich expatriates and poorer ones in a city-state where 40 percent of residents are foreign born.

Most of the cases among migrant workers are mild or asymptomatic, and none have required critical care, perhaps explaining why the dormitory outbreaks at first went unnoticed. In total, 11 people in Singapore have died of Covid-19, a relatively low fatality rate.

Tens of thousands of Singaporeans have donated funds for the well-being of migrant workers, and the expectation is that the government will deliver on its vow to treat them better. For now, though, the country is reeling from the pandemic’s assault on some of its most defenseless people.

READ MORE The resurgence of the coronavirus in Singapore The resurgence of the coronavirus in Singapore hints at a dark future for other countries whose viral curves have appeared to flatten.

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Iran eases restrictions on some businesses.

Image The Grand Bazaar market in Tehran on Monday. Credit... Atta Kenare/Agence France-Presse — Getty Images

Iran continued its gradual rebooting of its economy on Monday by reopening traditional bazaars and modern shopping malls and lifting travel restrictions around the country.

The government has called its plan “smart distancing,” rather than the strict social distancing measures imposed by most other countries hoping to flatten the rate of infection as they fight the coronavirus pandemic. But not much distancing was observed as commuters packed trains and buses and shoppers crowded the narrow, winding passageways that shape Tehran’s traditional bazaar.

President Hassan Rouhani of Iran said he was considering opening religious shrines, a potential vector for spreading the virus, two weeks earlier than scheduled based on requests from custodians of the religious centers.

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Health officials in the country, one of the first outside China to be hit hard by the virus, continued to warn that another surge of patients and deaths was inevitable. Different branches of the government sent conflicting messages to the public about the pros and cons of easing restrictions while the contagion had not been contained, testing was not widely available and the numbers of patients and deaths continued to surge.

“Contact among the public has increased with the opening of shopping centers and people moving around on public transportation,” said Alireza Zali, the head of Iran’s coronavirus relief committee. There has been a steady increase in people contracting the virus and being hospitalized, Mr. Zali said, including a 2 percent increase in patients being admitted to intensive care units within the past 24 hours.

The health ministry said on Monday that 1,294 new cases were reported in the past 24 hours and that 91 people had died. Iran’s official tally stands at 5,209 people dead and 83,505 infected.

Oil prices nosedived as the worldwide surplus grew.

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Oil prices fell sharply on Monday over growing concerns that the collapse in demand has far outstripped attempts to curb production and store the excess supply.

The price of the main U.S. benchmark, West Texas Intermediate, actually fell below zero — meaning that some sellers, fearing they would be unable to sell the oil and would have no place to put it, were willing to pay people to take it.

That stunning drop was largely a short-term aberration driven by the timing of futures contracts, but it highlighted the underlying severe damage to oil markets from the worldwide glut.

Other oil prices, less affected by futures, also fell, but not as drastically. Brent crude, an international benchmark, dropped more than 6 percent, below $27 a barrel — less than half its price two months ago.

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[Analysis: Oil collapse and covid-19 create toxic geopolitical stew.]

Stocks slumped, as well, with the S&P 500 index losing 1.8 percent on the day.

With much of the world in lockdown because of the pandemic, global demand for oil has collapsed, leading to record surpluses.

On April 12, major exporters like Saudi Arabia and Russia agreed to cut production by 9.7 million barrels a day, beginning in May, but that was not nearly enough to compensate for the drop in demand. Analysts estimate that consumption in April will have fallen by three times that amount.

At the same time, oil storage tanks in the United States, especially in the crucial site of Cushing, Okla., are nearing their limits.

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As a result, investors have little interest in bidding in the current round of West Texas Intermediate futures trading, which expires on Tuesday, for delivery of oil in May. Under those futures contracts, the crude is delivered to Cushing, but investors are worried that there will be no room to store it there.

The next futures contract for West Texas Intermediate, for delivery in June, fell about 12 percent on Monday, to around $22 a barrel.

GLOBAL OIL GLUT Read more about how the pandemic is wreaking havoc on oil prices and other global markets

Iraq begins to lift restrictions.

Image Iraqi civil defense workers disinfecting a street in the Tweirij district in Karbala, Iraq, last week. Credit... Mohammed Sawaf/Agence France-Presse — Getty Images

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Iraqis will join a growing list of nations that are starting to lift restrictions as they continue fighting the coronavirus.

The Iraqi government decided Monday to loosen a curfew it has had in place for nearly five weeks. It will allow some government employees to return to work and also some private sector workers, including those working in clothing stores and on construction sites.

Iraqis will be allowed to leave their home and neighborhoods from 6 a.m. to 7 p.m. for work or for buying food or going to pharmacies or medical appointments.

“Those who are carpenters, blacksmiths, car mechanics, barbers and others are permitted to work during the day as long as no more than three people are in the establishment at one time,” the official order said. Electricians and computer store workers are also included.

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Mosques will remain closed and so will restaurants, sporting events and cinemas.

Iraq has a relatively low number of cases, 1,574 as of April 20, and 82 deaths.

Iran, which shares a 1,000 mile border with Iraq, has also begun a gradual return to normal life.

Russians in the Caucasus mountains march shoulder-to-shoulder to protest lockdown measures.

In scenes reminiscent of anti-lockdown protests last week in Michigan and Wisconsin, hundreds of Russians took to the streets of a city in the Caucasus mountains on Monday demanding the resignation of the local governor and the lifting of his stay-at-home order.

The protest in Vladikavkaz, the capital of North Ossetia, was organized by political opponents of the governor, Vyacheslav Bitarov, a Kremlin ally who was appointed to his post by President Vladimir V. Putin in 2016.

Unlike President Trump, Mr. Putin has urged citizens to obey quarantine restrictions and show “discipline and responsibility” in managing an outbreak that he described on Sunday as “under total control” but still not at its peak in Russia.

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A mainly Christian pocket in a largely Muslim region, North Ossetia has a long record of loyalty to Moscow, which it looks to for protection and funding. The pandemic, however, has scrambled allegiances and political calculations.

Videos on social media showed people marching shoulder-to-shoulder in Vladikavkaz, in violation of social distancing recommendations backed by the Kremlin. They chanted slogans against the regional government and called on Mr. Bitarov to resign.

As has happened in other countries, anger at business closures and restrictions on movement has fed pre-existing political feuds and rage over corruption. Mr. Bitarov’s demands that people stay home caused fury amid reports that a brewery he owns has been exempted from the lockdown.

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Among those supporting the protest was Vadim Cheldiev, a prominent coronavirus skeptic who has dismissed the pandemic as a hoax. In a video posted online on Monday, he said coronavirus “doesn’t exist” but was a pretext to “establish total control over us all.”

OVD Info, a Russian group that monitors arrests, reported that the police detained two suspected organizers of the demonstration, along with several protesters. Officers in riot gear cordoned off government buildings in the city center and drove a crowd of demonstrators from a central square.

Russian news outlets blamed the protest on supporters of Vitaly Kaloev, an infamous former businessman and member of the regional council. Mr. Kaloev was jailed in Switzerland in 2004 for the murder of a Swiss air traffic controller whom he blamed for a plane crash that killed his wife and children.

Released from prison after just three years following intense lobbying by Moscow, Mr. Kaloev returned to a hero’s welcome in North Ossetia, but has bridled in recent years at being passed over by the Kremlin in favor of Mr. Bitarov.

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PANDEMIC IN RUSSIA Russia’s known coronavirus cases are concentrated in Moscow, but some remote regions are being hit hard, too

At some hospitals in Israel, relatives can visit dying Covid-19 patients.

Image Rinat Zita-Dishlo, right, saying goodbye to her dying mother, Batsheva Zita, 74, in the coronavirus ward of the Sourasky Medical Center on Sunday. Credit... Ziv Koren/Polaris

Several Israeli hospitals have begun to allow deathbed visits by family members of coronavirus patients, breaking with the strict ban that is in place across much of the world.

Proponents say that one or two relatives making short bedside visits while clothed head-to-toe in protective gear is manageable for hospital workers, and that the benefits outweigh the costs.

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Ronni Gamza, chief executive of Tel Aviv’s Sourasky Medical Center, said his hospital had adhered to the “default position” of barring all family visits to the coronavirus ward, but said it was over-the-top and, in his view, inhumane.

“We had anxiety, narrow thinking, a little bit of hysteria, and we were too conservative,” he said.

Israel’s hospitals have not been overrun like those in some countries, and the new visitation policy has been embraced by several major Israeli hospitals including Sheba Medical Center in Tel Hashomer, and Shaare Tzedek and Hadassah hospitals in Jerusalem.

Family visits, Dr. Gamzu said, require “less than one percent” of all the personal protective equipment his hospital uses. At peaks in the numbers of critical patients, Dr. Gamzu said, “You could say, ‘We are sorry, we do not have the capacity now.’ But to take that as a standard?”

Dr. Gamzu said he was urging Israeli health authorities to open nursing homes up for visits as well.

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Elisheva Stern was one of the first relatives given the chance to visit a dying patient, when she came to her father’s bedside earlier this month. “None of us want to say bye to our family,” she said. “But it’s really a gift.”

DYING ALONE In much of the world, Covid-19 patients in isolation cannot have visits — a harsh blow to the sick and their families.

Those we’ve lost: Luis Sepúlveda, a noted Chilean writer exiled by Pinochet.

Image Luis Sepúlveda, the Chilean novelist, was jailed by the Pinochet regime and then sent into exile. He died in Spain, hospitalized there early on in the pandemic. Credit... Marta Fernandez/Europa Press, via Associated Press

Luis Sepúlveda, a Chilean writer whose stay among Indigenous people in the Amazon led to his most celebrated novel and who was jailed during the dictatorship of Augusto Pinochet, died April 16 in Oviedo, Spain. He was 70.

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The cause was the novel coronavirus, according to Tusquets, his publishing house in Barcelona. Mr. Sepúlveda, who was hospitalized in February, was among the first wave of people in Spain to be diagnosed.

Mr. Sepúlveda published several novels, children’s stories and travel books, and he also wrote and directed films. He acquired fame with his novel “The Old Man Who Read Love Stories” (1988), which tells the story of a man who, together with his wife, leaves his mountain village to take part in the colonization of the Amazon.

The book was inspired by Mr. Sepúlveda’s stay in the 1970s with the region’s Shuar Indigenous people. A review in The New York Times by David Unger compared it to one of the early works of Gabriel García Márquez.

“In its simple language and philosophical underpinnings, it is magical, thanks to the author’s skill at describing jungle life,” Mr. Unger wrote. Mr. Sepúlveda wrote the screenplay for a 2001 movie version starring Richard Dreyfuss.

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Spain’s outbreak is easing, but its economic woes are just beginning.

Image A subway station in Barcelona last week. Spain has started easing some aspects of its lockdown. Credit... Samuel Aranda for The New York Times

Spain said on Monday that 399 people had died from the coronavirus in the previous 24 hours, the smallest daily percentage increase since a lockdown was imposed in mid-March, up just 1.9 percent up from the previous day. The number of people discharged from hospital is continuing to rise, now surpassing 80,000 recoveries, another sign of improvement.

But another report released on Monday was far less heartening: The country’s central bank warned that the Spanish economy could shrink as much as 13.6 percent this year. It also said that unemployment could rise to almost 22 percent, even excluding the thousands of workers whose contracts have been temporarily suspended under a government program designed to avoid mass layoffs. Spain’s jobless rate was almost 14 percent in February, before the outbreak took hold.

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Spain’s restrictions on movement have been some of the strictest in Europe, including orders to keep children inside. A nationwide lockdown has been extended into May, but the government has started rolling back some limits, allowing construction sites and factories to reopen.

Italy, like Spain, is moving carefully toward restoring economic activity, while Britain and France have signaled that they will not relax restrictions until next month.

The restrictions on Spain’s children are set to be loosened starting April 27, though the government has not given details on the changes. Fernando Simón, the director of the national center for health emergencies, said on Monday that it was important to clarify that “children will be able to get out on the street, but it will not be a free exit, to play.”

He added: “It’s not about opening the door and having the neighbors come out.”

As it considers reopening the economy, Spain is struggling to recount its dead. The latest figures from the Health Ministry do not match recent adjustments in regions that have taken into account data from funeral homes.

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Djokovic would prefer not to get vaccinated to resume playing, but doesn’t rule it out.

Image Novak Djokovic holding the winners trophy during the 2020 men’s singles final of the Australian Open in February. Credit... Asanka Brendon Ratnayake for The New York Times

Novak Djokovic, the world’s top ranked men’s tennis player, said on Sunday that he would have a difficult decision to make if receiving a coronavirus vaccine became a mandatory condition for competing on the circuit when play resumes.

“Personally I am opposed to vaccination and I wouldn’t want to be forced by someone to take a vaccine in order to be able to travel,” Djokovic said in comments reported and translated by Reuters. “But if it becomes compulsory, what will happen? I will have to make a decision. I have my own thoughts about the matter and whether those thoughts will change at some point, I don’t know.”

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Djokovic, the 32-year-old Serbian star who has won 17 Grand Slam singles titles, was speaking with a group of Serbian players on a live Facebook chat when he made the comment. Djokovic is staying in Spain with his wife Jelena and their two children during the lockdown.

In a statement released on Monday through his management team, he declined to say whether he opposed vaccines in general. He made it clear he was intent on exploring other options, but did not rule vaccination out if it became compulsory.

The professional tennis tour has been shut down because of the virus since early March and will resume no sooner than July 13. Wimbledon has been canceled for the first time since 1945 and dozens of tournaments, including the French Open, which was scheduled to be the next Grand Slam tournament, have been postponed.

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Wuhan lab rejects U.S. accusation that it was source of outbreak.

Image Rumors about the Wuhan Institute of Virology appeared shortly after the coronavirus outbreak began in China. Credit... Hector Retamal/Agence France-Presse — Getty Images

The Trump administration suggested that a Chinese laboratory may have been the source of the coronavirus outbreak, but a senior scientist at the lab in question has rejected the accusations, saying there are no signs that the virus was the product of human tampering.

The scientist, Yuan Zhiming, the director of a high-security virus research lab that is part of the Wuhan Institute of Virology, pushed back against the surge of speculation that the lab may have accidentally leaked the virus or was part of a conspiracy to release it.

“Without any evidence, and without any relationship to logic, he makes these allegations that are totally founded on speculation,” Mr. Yuan said of Senator Tom Cotton, an Arkansas Republican who was an early proponent of the theory that the lab was the origin of the virus.

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“I’ve long engaged in biosecurity management and project management in laboratories, and I know this would have been impossible,” Mr. Yuan said in an interview aired over the weekend by CGTN, the Chinese television broadcaster.

Secretary of State Mike Pompeo said last week that the Chinese government “needs to come clean” about the lab, and President Trump has kept the speculation alive, telling reporters that “more and more we’re hearing the story.”

But most scientists have dismissed the idea that the laboratory, built with French assistance, could have been the incubator, even inadvertently, of the new coronavirus. The French government has also said that there was no evidence of a link between the coronavirus and the lab.

But Mr. Yuan also ruefully suggested that no denial would halt the suspicions.

“I’m also sure that as long as the outbreak continues, especially abroad, these suspicions or discordant voices will never disappear,” he said.

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After second wave of infection, Hong Kong has first day with no new cases.

Image Wandering near a fishing village in Hong Kong on Sunday. Credit... Isaac Lawrence/Agence France-Presse — Getty Images

Hong Kong reported no new coronavirus cases on Monday, the first time since a second wave of imported infections hit the semiautonomous Chinese city in early March that there were no new daily infections.

The city has recorded 1,026 cases and four deaths since January, but cases tripled after residents returned to the city from hot spots in the United States and Europe last month. Hong Kong closed its borders to all nonresidents and shut gyms, movie theaters and government offices, and residents returning to the city are tested before they are allowed to return home for two weeks of self isolation. Fewer than 10 new cases were reported in more than a week.

The government also announced on Monday that residents returning to the city on late afternoon or evening flights would be required to stay overnight at a designated hotel until they are able to receive test results the following day.

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Medical experts warned that the city would have to record at least two incubation periods — or 28 days — before they could rule out further outbreaks, adding that many carriers of the disease do not show symptoms or fall ill.

Despite the downward trend in transmissions, social distancing restrictions are still in place in Hong Kong. Schools have been closed since late January, and final exams that normally take place in late April were canceled. Government offices, gyms and movie theaters remain closed, and gatherings of more than four people are banned.

Australia and New Zealand ease lockdowns as new infections drop.

Image Bondi Beach in Sydney, Australia, on April 5, when the country’s beaches were closed. Some reopened on Monday for exercise. Credit... Matthew Abbott for The New York Times

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Australia and New Zealand announced plans on Monday to ease lockdown restrictions as both countries have managed so far to control coronavirus outbreaks, reporting just a few new infections each day.

Careful and calibrated, the plans include a return to school for some children in the coming weeks as well as allowances for slightly more business activity, more freedom to exercise outdoors and the potential for gatherings of more than two people.

In Sydney, a few beaches reopened for exercise on Monday, leading to the return of surfers. In Maroubra, a coastal southern suburb, lifeguards used megaphones to warn surfers, runners and swimmers to stay physically distanced.

Many who ventured out expressed relief and awe at what the past month had brought.

“I’m just kind of laughing,” said Paul Beswich, 55, one of many residents who welcomed the chance to go for a swim. “I’ve lived here all my life, and we’ve always been told that if you’ve got a virus, go flush it out in the water. Now we can.”

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Australia and New Zealand have benefited from an early, aggressive response to the pandemic. In Australia, public health laboratories started building test kits in January.

As of Monday, the country had tested more than 422,000 people, and confirmed 6,619 confirmed and 71 deaths. None of its hospitals are overwhelmed. For eight straight days, the country has recorded fewer than 50 new cases, after a daily peak of nearly 500 on March 28. That was roughly when the government asked people to stay home, with the exception of essential activities, including shopping and exercise.

New Zealand’s restrictions were more severe, with Prime Minister Jacinda Ardern announcing a total lockdown on March 25, asking New Zealanders to act as if they had the virus. The restrictions produced a result roughly in line with Australia’s. New Zealand has recorded just over 1,100 infections and 12 deaths after conducting 85,000 tests from a population of nearly 4.9 million.

Starting next Monday, it will begin to allow slightly more activity. Construction will be allowed to restart. Schools will reopen as of April 28 to some students, and funerals and weddings of up to 10 people could be allowed.

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“Stay strong, stay home, be kind, and let’s finish what we started,” Ms. Ardern said on Monday.

U.S. ambassador in Kenya ignites outrage over virus criticism.

Image The Kibera slum in Kenya’s capital Nairobi in early April. Credit... Tyler Hicks/The New York Times

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Comments from the top United States diplomat in Kenya have caused an uproar after he said that only a small part of the country’s population was adhering to rules aimed at curbing the spread of the coronavirus.

In a Twitter post on Sunday, the ambassador, Kyle McCarter, wrote, “Only a fraction of the wananchi are wearing masks and social distancing,” using the Swahili word for citizens.

“None of us know the magnitude of this Wuhan flu,” he continued, “but we must take basic known wise precautions. It is only for a short time.”

The comment sparked outrage, with some noting that social distancing was an unimaginable luxury for poor people living in overcrowded and cramped conditions. Others also questioned how he came to his conclusion given that Nairobi was on partial lockdown and movement in and out of the city was banned. Mr. McCarter doubled down writing in a follow-up post, “The further you get from Nairobi the less compliance there is. Trust me.”

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When Twitter user Allan Ogera questioned him on the number of masks the United States has donated to Kenya, Mr. McCarter retorted, “You would not be able to test in Kenya if not for USA marafiki,” which means ‘friends’ in Swahili.

Some social media users also criticized the ambassador’s decision to call the coronavirus “Wuhan flu,” saying he was “trying to please” President Trump who nominated him for the post in 2019 and who has insisted on calling the coronavirus the “Chinese virus.” The disease is thought to have first emerged in the central Chinese city of Wuhan.

Kenya has 270 confirmed coronavirus cases, according to the latest figures, and a total of 14 deaths. To curb the spread of the virus, authorities have mandated the wearing of masks, imposed a nationwide dusk to dawn curfew, closed the biggest shopping district in the capital and introduced partial lockdowns in four out of the country’s 47 counties.

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Thousands who died in Italy’s nursing homes were not counted among fatalities.

Image Preparing a stretcher for a suspected coronavirus patient in Bergamo, Italy, last month. Credit... Fabio Bucciarelli for The New York Times

The coronavirus outbreak tore through communities in northern Italy and overwhelmed the health care system with such force that only now is the true scale of the outbreak beginning to emerge. Like other hard-hit countries, including China and Spain, Italy has had to revisit its tally of the dead.

Health experts in Italy say they now believe thousands of nursing home residents were initially unaccounted for. A recent survey by Italy’s national health institute estimated that 40.2 percent of the 6,773 people who died in Italian nursing homes between Feb 1 and April 14 had either a confirmed case of Covid-19 or symptoms consistent with the infection.

“We observed that most deaths occurred in the second half of March, at the peak of the Covid infection, while some of the earlier deaths coincided with the influenza season,” said Graziano Onder, director of the Aging Department at the National Health Institute, which presented the data on Friday. Only the 364 nursing home residents who had tested positive were included in the official toll kept by the country’s Civil Protection Department.

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The actual number of Covid-19 deaths in these nursing homes may never be known because initially testing was infrequent.

“Because the swabs were so difficult to obtain, at first priority was given to hospitals,” Dr. Onder said. “Only more recently were nursing homes added to the priority list.”

About a third of Italy’s 3,420 public or publicly funded nursing homes, which serve around 80,000 people, participated in the survey, which also sought to monitor the difficulties these structures faced during the early weeks of the outbreak. Shortages of masks, gloves and other protective equipment were reported most frequently.

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THE LIFE AND DEATH SHIFT A photographer documented the medical workers on Italy’s front line.

Reporting was contributed by Hannah Beech, Richard Pérez-Peña, Karen Zraick, David M. Halbfinger, Knvul Sheikh, Elisabetta Povoledo, Tiffany May, Melissa Eddy, Carlotta Gall, Damien Cave, Abdi Latif Dahir, Megan Specia, Daniel Victor, Andrew Higgins, Ernesto Londoño, Raphael Minder, Seth Schiesel, Farnaz Fassihi, Alissa J. Rubin, Christopher Clarey, Kenneth Chang and Martin Selsoe Sorensen.

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