How to reopen schools: What science can teach us

Data from around the world clearly shows that children are far less likely to become seriously ill from the coronavirus than adults. But there are big unanswered questions, including how often children become infected and what role they play in transmitting the virus. Some research suggests younger children are less likely to infect other people than teenagers are, which would make opening elementary schools less risky than high schools, but the evidence is not conclusive.

The experience abroad has shown that measures such as physical distancing and wearing masks in schools can make a difference. Another important variable is how widespread the virus is in the community overall, because that will affect how many people potentially bring it into a school.

For most districts, the solution won’t be an all-or-nothing approach. Many systems, including the nation’s largest, New York City, are devising hybrids that involve spending some days in classrooms and other days online.

“You have to do a lot more than just waving your hands and say make it so,” said Dr. Joshua Sharfstein, a professor of the practice at Johns Hopkins Bloomberg School of Public Health. “First you have to control the community spread and then you have to open schools thoughtfully.”

The Transmission Puzzle

Though children are at much lower risk of getting seriously ill from the coronavirus than adults, the risk is not zero. A small number of children have died and others needed intensive care because they suffered a respiratory failure or an inflammatory syndrome that caused heart or circulatory problems.

The larger concern with reopening schools is the potential for children to become infected, many with no symptoms, and then spread the virus to others, including family members, teachers and other school employees. Most evidence to date suggests that even if children under age 12 are infected at the same rates as the adults around them, they are less likely to spread it. The American Academy of Pediatrics has cited some of this data to recommend that schools reopen with proper safety precautions.

But the bulk of the evidence was collected in countries that were already in lockdown or had begun to implement other preventive measures. And few countries have systematically tested children for the virus or for antibodies that would indicate whether they had been exposed to the virus.

Infectious disease specialists have been modeling schools’ impact on community spread beginning as far back as February.

In March, most modelers agreed that closing schools would slow the progression of infections. But wider measures, like social distancing, proved to have a far greater containing effect, overshadowing the results of school closings, according to recent analyses.

So far, countries that reopened schools after reducing infection levels — and imposed requirements like physical distancing and limits on class sizes — have not seen a surge in coronavirus cases.

Norway and Denmark are good examples. Both reopened their schools in April, a month or so after they were closed, but they initially opened them only for younger children, keeping high schools shut until later. They strengthened sanitizing procedures, and have kept class size limited, children in small groups at recess and space between desks. Neither country has seen a significant increase in cases.

There have not yet been rigorous scientific studies on the potential for school-based spread, but a smattering of case reports, most of them not yet peer-reviewed, bolster the notion that it is not inevitably a high risk. Case studies in some countries suggest differences in virus transmission in younger children compared with older children.

In one community in northern France, Crépy-en-Valois, two high school teachers became ill with COVID-19 in early February, before schools closed. Scientists from the Institut Pasteur later tested the school’s students and staff for coronavirus antibodies. They found antibodies in 38% of the students, 43% of the teachers, and 59% of other school staff, said Dr. Arnaud Fontanet, an epidemiologist at the institute who led the study and is a member of a committee advising the French government.

“Clearly you know that the virus circulated in the high school,” Fontanet said. Later, the team tested students and staff from six elementary schools in the community. The closure of schools in mid-February provided an opportunity to see if younger children had become infected when schools were in session, the point when the virus struck high school students.

Researchers found antibodies in only 9% of elementary students, 7% of teachers and 4% of other staff. They identified three students in three different elementary schools who had attended classes with acute coronavirus symptoms before the schools closed. None appeared to have infected other children, teachers or staff, Fontanet said. Two of those symptomatic students had siblings in the high school and the third had a sister who worked in the high school, he said.

Testing for infections in schools is essential, public health experts said. The Centers for Disease Control and Prevention recommends testing of students or teachers based only on symptoms or a history of exposure. But that will not catch everyone who is infected.

“We know that asymptomatic or pre-symptomatic spread is real, and we know that kids are less likely to show symptoms if they’re infected than adults,” said Dr. Megan Ranney, an emergency medicine doctor and expert in adolescent health at Brown University. Schools should randomly test students and teachers, she said, but that may be impossible given the lack of funding and limited testing even in hospitals.

The CDC has outlined steps schools can take to minimize the risks for students, including maintaining a distance of 6 feet, washing hands and wearing masks.

“The guidelines are already exceptionally weak,” said Carl Bergstrom, an infectious diseases expert at the University of Washington in Seattle. He and others said they feared that the recommendations would get watered down even more in response to political pressure.

Dr. Kathryn Edwards, an infectious disease specialist and professor of pediatrics at Vanderbilt University School of Medicine, is advising Nashville, Tennessee, schools on reopening approaches. She said the district is still evaluating how far apart desks should be. “Some people say you only need 3 feet and others say you need 6 feet, and others wonder with the aerosol issue, do we need more distance?”

Edwards said she was disappointed by Nashville’s decision, announced Thursday, to conduct classes online for the first month of school, at least until Labour Day.

Keeping schools closed for a prolonged stretch has worrisome implications for social and academic development, child development experts say. It also became evident this spring that denying children a real school day deepened racial and economic inequalities.

“There is really damage to kids if they don’t go to school,” Edwards said. “I think we have got to think of the kids and getting them back to school safely.”