When Covid Subsided, Israel Reopened Its Schools. It Didn’t Go Well.

JERUSALEM — As the United States and other countries anxiously consider how to reopen schools, Israel, one of the first countries to do so, illustrates the dangers of moving too precipitously.

Confident it had beaten the coronavirus and desperate to reboot a devastated economy, the Israeli government invited the entire student body back in late May.

Within days, infections were reported at a Jerusalem high school, which quickly mushroomed into the largest outbreak in a single school in Israel, possibly the world.

The virus rippled out to the students’ homes and then to other schools and neighborhoods, ultimately infecting hundreds of students, teachers and relatives.

Other outbreaks forced hundreds of schools to close. Across the country, tens of thousands of students and teachers were quarantined.

Israel’s advice for other countries?

“They definitely should not do what we have done,” said Eli Waxman, a professor at the Weizmann Institute of Science and chairman of the team advising Israel’s National Security Council on the pandemic. “It was a major failure.”

The lesson, experts say, is that even communities that have gotten the spread of the virus under control need to take strict precautions when reopening schools. Smaller classes, mask wearing, keeping desks six feet apart and providing adequate ventilation, they say, are likely to be crucial until a vaccine is available.

“If there is a low number of cases, there is an illusion that the disease is over,” said Dr. Hagai Levine, a professor of epidemiology at Hebrew University-Hadassah School of Public Health. “But it’s a complete illusion.”

“The mistake in Israel,” he said, “is that you can open the education system, but you have to do it gradually, with certain limits, and you have to do it in a very careful way.”

The United States is facing similar pressures to fully reopen schools, and President Trump has threatened to withhold funding for districts that don’t reopen. But the U.S. is in a far worse position than Israel was in May: Israel had fewer than 100 new infections a day then. The U.S. is now averaging more than 60,000 new cases a day, and some states continue to set alarming records.

Israel’s handling of the pandemic was considered successful at first. The country of nine million quickly closed its borders, shuttered schools in mid-March and introduced remote learning for its two million students. In April, Passover and Ramadan were celebrated under lockdown.

By early May, infection rates had fallen from more than 750 confirmed cases a day to double digits. The youngest students, grades three and under, and older students taking final exams returned in small groups, splitting the week to take turns using classrooms.

Then, emboldened by the dropping infection rates, the government completely reopened schools on May 17, the day a new government was sworn in.

In his inaugural speech, Prime Minister Benjamin Netanyahu promised a new budget that would deliver three things: “Jobs, jobs, jobs.” His new education minister, Yoav Gallant, said that the school system’s “immediate mission” was to allow parents to return to work with peace of mind.

Inna Zaltsman, an Education Ministry official, said administrators also wanted “to return the children to routine as much as possible, for their emotional and pedagogic well-being.”

Shopping malls, outdoor markets and gyms had already reopened, and soon houses of worship, restaurants, bars, hotels and wedding halls did too. Mr. Netanyahu told Israelis to grab a beer and, while taking precautions, “Go out and have a good time.”

In hindsight, that advice was wildly premature.

That same day, a mother phoned a teacher at Jerusalem’s historic Gymnasia Ha’ivrit high school. Her son, a seventh-grade student there, had tested positive for the virus.

By the next day, the school confirmed another case in the ninth grade. Ultimately, Israeli officials said, 154 students and 26 staff members were found to be infected.

“There was a general euphoria among the public, a sense that we had dealt with the first wave well and that it was behind us,” said Danniel Leibovitch, Gymnasia’s principal. “Of course, that wasn’t true.”

The Education Ministry had issued safety instructions: Masks were to be worn by students in fourth grade and higher, windows kept open, hands washed frequently and students kept six feet apart whenever possible.

But in many Israeli schools, where up to 38 children squeeze into classrooms of about 500 square feet, physical distancing proved impossible.

Unable to comply with the rules, some local authorities ignored them or simply decided not to reopen at full capacity.

Then a heat wave hit. Parents complained that it was inhumane to make children wear masks in steaming classrooms where open windows nullified the air conditioning.

In response, the government exempted everyone from wearing masks for four days, and schools shut the windows.

That decision proved disastrous, experts say.

“Instead of canceling school in those days, they just told the kids ‘OK, well you have to stay in the class with the air conditioning on and take your masks off,’ so you have no ventilation really,” said Dr. Ronit Calderon-Margalit, a professor of epidemiology at Hebrew University-Hadassah Braun School of Public Health. “You have the ideal circumstances for an outbreak.”

The Gymnasia became a petri dish for Covid-19.

When the first case was discovered, the student’s classmates, teachers and other contacts were quarantined. After the second case, which was not directly linked to the first, the school was closed and everyone was instructed to quarantine for two weeks. All students and staff were tested, often waiting in line for hours.

About 60 percent of infected students were asymptomatic. Teachers, some of whom had been teaching multiple classes, suffered the most and a few were hospitalized, the principal said.

Parents were furious. Oz Arbel told Israel’s Army Radio that for a school project, his daughter’s classmates sat at a table and passed around a cellphone with a teacher who was showing symptoms. His daughter and wife became infected.

One Gymnasia student, Ofek Amzaleg, told Kan public radio that a teacher who coughed in class and joked that he didn’t have coronavirus was among those who tested positive. Ofek also became infected.

Mr. Leibovitch, the principal, said he had no knowledge of any teacher coming in with symptoms.

Seeking to contain the contagion, the Education Ministry vowed to shut any school with even one Covid-19 case. It ultimately closed more than 240 schools and quarantined more than 22,520 teachers and students.

When the school year ended in late June, the ministry said, 977 pupils and teachers had contracted Covid-19.

But the Health Ministry, lacking the infrastructure and resources, did not make contact tracing a priority. In the Gymnasia case, Professor Waxman said, nobody even identified which buses the students had ridden on to school.

Proms were canceled, but graduating seniors in the central city of Ra’anana held an underground prom party anyway. Dozens contracted the virus.

A nursery school teacher, Shalva Zalfreund, 64, sent a note to parents saying she believed she had been infected in her school, where some parents had sent their children from homes with cases of the virus. She died in July.

Outside school walls, the coronavirus returned with a vengeance. Covid wards that had closed with festive ceremonies in late April began filling again, with confirmed infections spiraling to about 800 a day by late June and more than 2,000 a day by late July.

Some blamed the hasty school reopening as a major factor in the second wave. Siegal Sadetzki, who resigned in frustration last month as Israel’s director of public health services, wrote that insufficient safety precautions in schools, as well as large gatherings like weddings, fueled a “significant portion” of second-wave infections.

But others said singling out schools was unfair when the real problem was that everything reopened too quickly.

“The single super-spreader event in the Gymnasia just happened to be in a school,” said Dr. Ran Balicer, an Israeli health care official and adviser to the prime minister on the pandemic. “It could have happened in any other setting.”

Now Israel is confronting the same questions as other countries, trying to learn from its mistakes in planning for the school year that begins Sept. 1.

Public health experts worldwide have coalesced around a set of guidelines for reopening schools.

A major recommendation is to create groups of 10 to 15 students who stay together in classrooms, at recess and lunchtime, with teachers assigned to only one group. Each group has minimal contact with other groups, limiting any spread of infection. And if a case of Covid-19 emerges, one group can be quarantined at home while others can continue at school.

Other key recommendations include staggering schedules or teaching older students online, keeping desks several feet apart, sanitizing classrooms more frequently, providing ventilation and opening windows if possible, and requiring masks for staff and students old enough to wear them properly.

Israel has already moved in that direction.

The government recently appointed a coronavirus czar, Dr. Ronni Gamzu, who transferred responsibility for virus testing and investigation from the Health Ministry to the military. “This is an operation, not medicine,” he declared.

On Sunday, the government approved plans for returning only grades two and lower to school in full-size classes in the fall. Younger children are less likely to become seriously ill, and some studies have suggested that they are less likely than adults and teenagers to transmit the virus to others.

The plans also call for splitting older students into capsules of 18 and for mostly online instruction for grades five and above. Principals will have flexibility to adjust their school’s policies based on local conditions.

Even those measures may not be enough.

Menashe Levy, president of the Israeli High School Principals Association, arranged desks six feet apart in a standard classroom. It could accommodate 14 students, not 18.

But Israel is plunging ahead. Only one option has been ruled out: closing the schools.

“This is a long-term pandemic,” said Dr. Nadav Davidovitch, a pandemic policy adviser to the government. “We cannot close schools for a year.”

Isabel Kershner reported from Jerusalem, and Pam Belluck from the United States.