Only a few weeks ago, China, where the outbreak began, was the only country to suspend classes. But the virus has spread so quickly that by Wednesday, 22 countries on three continents had announced school closures of varying degrees, leading the United Nations to warn that “the global scale and speed of the current educational disruption is unparalleled.”

At the this time students in South Korea, Iran, Japan, France, Pakistan and elsewhere — some for only a few days, others for weeks on end.  Italy is suffering one of the deadliest outbreaks outside China, according to the officials on Wednesday said that they would extend school closures beyond the north, where the government has urge a lockdown on several towns, to the entire nation. All schools and universities will remain closed until March 15, officials said.

   On the West Coast of the United States, the region with the most American infections , Los Angeles declared a state of emergency on Wednesday, advising parents to steel themselves for school closures in the nation’s second-largest public school district. Washington State, which has reported at least 10 deaths from the outbreak, has closed some schools, while on the other side of the country in New York, newly discovered cases have led to the closure of several schools as well.

    The speed and scale of the educational commotion — which now affects 290.5 million students worldwide, the United Nations says — has little parallel in modern history, educators and economists contend. Schools provide structure and support for families, communities and entire economies. The effect of closing them for days, weeks and sometimes even months could have untold repercussions for children and societies at large.

“They’re always saying, ‘When can we go out to play? When can we go to school?’” said Gao Mengxian, mean while Gao Mengxian is a security guard in Hong Kong whose two daughters have been stuck at home because school has been suspended since January.

In some countries, older students have missed important study sessions for college admissions exams, while younger ones have risked falling behind in reading and math. Parents have lost wages, tried to work at home or scrambled to find child care. Some have moved children to new schools in areas unaffected by the coronavirus, and lost important event like graduation ceremonies or last days of school.

“I don’t have data to offer, but can’t think of any instances in modern times where advanced economies shut down schools nationally for prolonged periods of time,” said Jacob Kirkegaard, a senior fellow at the Peterson Institute for International Economics in Washington.

In Hong Kong, families like Ms. Gao’s, 48 have struggled to maintain some appearance  routine  stopped working to watch her daughters and started scrimping on household expenses. She ventures outside just once a week and spends the most time helping her girls, 10 and 8 years respectively, with online classes, fumbling through technology that leaves her confused and her daughters frustrated.

Governments are trying to help. Japan is offering subsidies to help companies offset the cost of parents’ taking time off. France has promised 14 days of paid sick leave to parents of children who must self-isolate, if they have no choice but to watch their children.

But the burdens are widespread, touching corners of society seemingly unconnected to education. In Japan, schools have canceled bulk food deliveries for lunches they will no longer serve, hurting farmers and suppliers. In Hong Kong, an army of domestic helpers has been left unemployed after wealthy families enrolled their children in schools overseas.

      Julia Bossard, a 39-year-old mother of two in France, said she had been forced to rethink her entire routine since her older son’s school was closed for two weeks for disinfection. Her days now consist of helping her children with homework and scouring supermarkets for fast-disappearing pasta, rice and canned food. “We had to reorganize ourselves,” she said.

       School and government officials have sought to keep children learning — and occupied — at home. The Italian government created a web page to give teachers access to video conference tools and ready-made lesson plans.Mongolian television stations are airing classes. Iran’s government has made all children’s internet content free.

Students even take online physical education: At least one school in Hong Kong requires students — in gym uniform — to follow along as an instructor demonstrates push-ups onscreen. Each student’s webcam provides proof.

The offline reality, though, is challenging. Technological hurdles and unavoidable distractions pop up when children and teenagers are left to their own devices — literally.

Thira Pang, a 17-year-old high school student in Hong Kong, has been repeatedly late for class because her internet connection is slow. She now logs on 15 minutes early.

“It’s just a bit of luck to see whether you can get in,” she said.

The new classroom at home poses greater problems for younger students, and their older caregivers. Ruby Tan, a teacher in Chongqing, a city in southwestern China that suspended school last month, said many grandparents were helping with child care so that the parents can go to work. But the grandparents do not always know the technology.

“They don’t have any way of supervising the children’s learning, and instead let them develop bad habits of not being able to focus during study time,” Ms. Tan said.

Some interruptions are unavoidable. Posts on Chinese social media show teachers and students climbing onto rooftops or hovering outside neighbors’ homes in search of a stronger internet signal. One family in Inner Mongolia packed up its yurt and migrated elsewhere in the grasslands for a better web connection, a Chinese magazine reported.

The closings have also altered the normal milestones of education. In Japan, the school year typically ends in March. Many schools are now restricting the ceremonies to teachers and students.

When Satoko Morita’s son graduated from high school in Akita Prefecture, in northern Japan, on March 1, she was not there. It will be the same for her daughter’s ceremony at elementary school.

“My daughter asked me, ‘What’s the point of attending and delivering speeches in the ceremony without parents?’” she said.

For Chloe Lau, a Hong Kong student, the end of her high school education came abruptly. Her last day was supposed to be April 2, but schools in Hong Kong will not resume until at least April 20.

        With the closings, families must rethink how they support themselves and split household responsibilities. The burden has fallen particularly hard on women, who across the world are still largely responsible for child care.

The 11-year-old son of Lee Seong-yeon, a health information manager at a hospital in Seoul, South Korea, has been out of class since the government suspended schools nationwide on Monday. South Korea has the highest number of coronavirus cases outside China.

Working from home was never an option for Ms. Lee: She and her husband, also a hospital employee, have more work duties than ever. So Ms. Lee’s son spends each weekday alone, eating lunchboxes of sausage and kimchi fried rice premade by Ms. Lee.

“I think I would have quit my job if my son were younger, because I wouldn’t have been able to leave him alone at home,” Ms. Lee said.

Still, she feels her career will suffer. “I try to get off work at 6 p.m. sharp, even when others at the office are still at their desks, and I run home to my son and make him dinner,” she said. “So I know there is no way I am ever going to be acknowledged for my career at work.”

For mothers with few safety nets, options are even more limited.

In Athens, Anastasia Moschos said she had been lucky. When her 6-year-old son’s school was closed for a week, Ms. Moschos, 47, an insurance broker, left her son with her father, who was visiting. But if the schools stay closed, she may have to scramble for help.

“The assumption is that everyone has someone to assist,” she said. “That’s not the case with me. I’m a single mother, and I don’t have help at home.”

Even mothers able to leave affected areas have trouble finding child care. Cristina Tagliabue, a communications entrepreneur from Milan, the center of Italy’s outbreak, recently moved with her 2-year-old son to her second home in Rome. But no day care facility would accept her son because other parents did not want anyone from Milan near their children, Ms. Tagliabue said.

The closings in Italy — which include day care in addition to schools and universities — are likely to create problems for parents nationwide.

Ms. Tagliabue has turned down several job proposals, she said, since she is unable to work at home without a babysitter for her young child.

“It’s right to close schools, but that has a cost,” she said. “The government could have done something for mothers — we are also in quarantine.”

     The epidemic has shaken entire industries that rely on the rituals of students in school and parents at work.

School administrators in Japan, surprised by the abrupt decision to close schools, have rushed to cancel orders for cafeteria lunches, stranding suppliers with unwanted groceries and temporarily unneeded employees.

Kazuo Tanaka, deputy director of the Yachimata School Lunch Center in central Japan, said it scrapped orders for ingredients to make about 5,000 lunches for 13 schools. It would cost the center about 20 million yen, nearly $200,000, each month that school was out, he said.

“Bakeries are blown,” said Yuzo Kojima, secretary general at the National School Lunch Association. “Dairy farmers and vegetable farmers will be hit. The workers at the school lunch centers cannot work.”

To blunt the effects, Japan’s government is offering financial help to parents, small businesses and health care providers. But school lunch officials said they had not heard about compensation for their workers.

Demand for nannies had already dropped by a third when the outbreak began, because many companies allowed parents to work from home, said Felix Choi, the director of Babysitter.hk, a nanny service. Now some expatriate families have left the city rather than wait out the closings.

“Over 30 percent of our client base is Western expat families, and I’m not seeing many of them coming back to Hong Kong at this moment,” Mr. Choi said. “Most of them informed us they will only come back after school restarts.”Coronavirus