When researchers at Duke University School of Medicine asked selected parents in the Raleigh-Durham metropolitan area to track symptoms in children who tested positive for the coronavirus early in the pandemic, among the notable answers was this: After 28 days, more than one-third of the 6- to 13-year-olds had shown no symptoms at all.
That finding poses implications for school systems that have brought students back to class or are making plans to do so. Will elementary and middle schoolers who show no signs of infection spread the virus to other kids and staff?
As calls rise to get more kids back into classrooms for their educational, emotional, and physical health, medical schools and university hospitals are helping educators assess such risks and develop plans — plans built on data from schools that have opened and evidence about how kids catch and transmit the virus.
The early data suggest that schools can reopen safely under certain conditions, but the analyses come with follow-up questions and multiple caveats — the most basic of which is some form of, “That’s what we know so far.”
“We’re nine to 10 months into a brand-new disease,” cautions Helen Bristow, MPH, program manager of Duke’s ABC Science Collaborative, which guides schools on COVID-19 safety. “We’re regularly learning something we didn’t know before.”
Here is some of what researchers are sharing with school systems about how children catch, are affected by, and transmit the coronavirus.
The virus spreads in schools — but schools are rarely superspreaders
Early data from K-12 schools do not confirm fears that bringing students together in classrooms inevitably creates COVID-19 petri dishes — although the absence of a standardized national database of school cases makes it impossible to know for sure. University researchers have partly filled the void with a plethora of data analyses from selected schools and grades.
One of the largest studies, led by Brown University economist Emily Oster, PhD, analyzed in-school infection data from 47 states over the last two weeks of September. Among more than 200,000 students and 63,000 staff who had returned to school, Oster reported an infection rate of 0.13% among students and 0.24% among staff.
The low infection rates support what other researchers have seen in smaller samples.
“What we haven’t seen are superspreader events” that ignited in schools, says Sallie Permar, MD, PhD, a professor of pediatrics and immunology at Duke. “The fear that you’d have one infected kid come to school, and then you’d have many other kids and teachers and relatives [at home] get infected — that hasn’t happened.”
Nevertheless, many schools have experienced infections that compelled them to quarantine some students and staff at home for a time, and some school districts in Georgia and Utah have shifted to more online learning after experiencing severe outbreaks.
“The fear that you’d have one infected kid come to school, and then you’d have many other kids and teachers and relatives [at home] get infected — that hasn’t happened.”
Sallie Permar, MD, PhD
Professor of pediatrics and immunology at Duke University School of Medicine
One characteristic common among schools that are doing well: They are operating under capacity, as they’ve opened with arrangements designed to minimize crowding, such as grouping students to come to school on different days and allowing students to attend only from home. So, while New York City touted a miniscule 0.15% infection rate in its schools in mid-October, the city reported that just over one-quarter of its students had attended any classes in person.
And while COVID-19’s light impact on K-12 schools so far has spurred calls to fill classrooms, coronavirus infection surges in many parts of the country pose a growing threat. In recent weeks, outbreaks have forced some schools to revert to distance learning while others have postponed their reopening plans.
School outbreaks typically come from the community — not vice versa
Infections in schools reflect infection levels and mitigation practices in their communities. The COVID-19 surge in Utah has fueled one of the country’s biggest public school outbreaks. Some school districts in the Salt Lake City area remained open this fall even after local coronavirus infection rates reached more than double the level at which the state recommended distance learning.
That stuns Benjamin Linas, MD, MPH, an associate professor of medicine and epidemiology at Boston University School of Medicine who has advocated for opening schools under strict safety measures. “You can only open your school safely if you have COVID under control in your community,” Linas says.
The surge in Utah has been partly attributed to public resistance to infection mitigation recommendations, such as physical distancing and wearing masks — a resistance that carried into the schools, many of which did not require such measures among students. Maintaining those practices in both schools and their surrounding communities is critical, says Peggy Thompson, RN, director of infection prevention at Tampa General Hospital (TGH).
“You can have the best laid plans” in classrooms, but “if kids are not following social distancing and mask usage outside of school, they’re going to bring COVID into the school with them,” says Thompson, who works with schools to contain the virus through an initiative called TGH Prevention Response Outreach.
“You can only open your school safely if you have COVID under control in your community.”
Benjamin Linas, MD, MPH
Associate professor of medicine and epidemiology at Boston University School of Medicine
TGH and other teaching hospitals that consult with schools about operating safely during the pandemic find that students and staffers who have tested positive for the coronavirus usually contracted the virus outside of school.
“There’s a party, students are gathering unmasked, and [the virus] is brought back to school,” says Joan Zoltanski, MD, who oversees the Healthy Restart initiative at University Hospitals in Cleveland to help schools and businesses operate safely. She cites gatherings of family members from different households as another common viral source for students and staff.
That’s why researchers advise that, as Permar says, “You can’t stop cases from coming on school grounds. The goal is to eliminate transmissions on the campus.”
Children transmit the virus — but not how adults do
Several studies have found that children transmit the virus, but perhaps not as often as adults, especially in younger age groups. It’s not clear why.
The Duke study found that children carry large amounts of the virus in their respiratory systems, says Matthew Kelly, MD, an assistant professor of pediatrics at Duke who co-authored the study with Permar and others. He posits that for several reasons, younger children might not transmit the virus as effectively as adults; for instance, children may not generate aerosols as effectively as older children and adults when they cough, sneeze, or breathe.
In addition, children might not cough, sneeze, or struggle to breathe as much with COVID-19 as they do when afflicted with other respiratory illnesses, such as the flu — because, as the Centers for Disease Control and Prevention says, “most children with COVID-19 have mild symptoms or have no symptoms at all.” While that’s good for those kids, the phenomenon opens a vulnerability for schools where safety strategies include screening students for symptoms.
Because researchers have found that people transmit the coronavirus even when they experience mild or no symptoms, Kelly cautions that “trying to use symptom-based screening strategies may not effectively pick up infections among school-aged children.”
Behavioral challenges matter — sometimes as much as biology
When school districts began making plans this summer to reopen some schools, many staffers and parents objected that teachers would not be able to get younger kids to stick with wearing masks, washing their hands frequently, and maintaining distance from each other (which varies among schools from three to six feet). Researchers who have worked with schools on those plans say the younger children have complied quite well, especially when adults have made clear that those measures are mandated and practiced those measures themselves.
In schools with such mandates, coronavirus transmissions appear to remain low. The COVID-19 School Response Dashboard — built by the technology company Qualtrics based on data provided by schools that choose to participate, and which Oster used for her analysis — shows fewer reported infections in schools that require masks and six-foot distancing.
“The teachers and principals are nervous. They’re in need of information they can trust.”
Helen Bristow, MPH
Program manager of Duke’s ABC Science Collaborative, which guides schools on COVID-19 safety
Mandates or not, the most difficult area to get consistent compliance with safety measures might be the cafeteria. “They’re like the free-for-all zone,” says Thompson, the nurse at TGH. “That’s where you can take your mask off because you can eat and drink. They [school administrators] will put set-ups in place for where the kids need to socially distance, and the kids all pile around one table anyway. They’re social animals.”
Sticking to safety measures during unstructured time outside of classrooms has proven particularly challenging for older students, both in school and beyond, according to Zolanski at University Hospitals in Cleveland. She notes that high schoolers, compared with younger students, tend to socialize with more peers — and are more often away from close adult supervision.
“They’re the most challenging because they are interacting outside of school,” Zolanski says.
Schools thirst for trusted advice — and largely accept it
Medical schools, university hospitals, and individual doctors and researchers are working with schools around the country to operate as safely as possible and make adjustments based on new data and evolving knowledge.
The largest such effort is the ABC Science Collaborative, established this summer by the Duke Clinical Research Institute and the University of North Carolina at Chapel Hill School of Medicine with a grant from the National Institutes of Health. The core of the collaboration is a multidisciplinary scientific advisory board that explains data on epidemiology, transmission rates, and other research through webinars, online resources, and data-sharing with participating school districts, according to Bristow.
The initiative works with 57 of North Carolina’s 115 school districts and hopes to expand to other states. “The teachers and principals are nervous,” she says. “They’re in need of information they can trust.”
In other states, academic medical centers are increasingly consulting with schools and businesses about how to operate safely. “The mitigation tactics are not as straightforward as one might think,” explains William Lennarz, MD, system chair for pediatrics at Ochsner Health, which provides support for several hundred schools in Louisiana.
Among the questions Ochsner has worked through with schools: “Do you quarantine a whole class when you identify one suspected case? Does everyone from the class who maintained a safe distance of six feet from the infected student have to go home? Do you wait for another test result?”
The answers, according to Lennarz, have depended on an array of factors in each situation — a few of which led schools to temporarily move a class or a grade to remote learning.
In other communities, doctors and other health professionals provide that kind of expertise on a more individual level. In Boston, Linas serves on the Public Health, Safety and Logistics advisory panel for his local school district in the suburb of Brookline. The panel, composed of physicians and public health experts, uses the latest research and data to assist the school system in deciding what measures to take as it operates on a hybrid model of in-person and at-home learning.
Linas says that amid the societal tension and disagreements about how to respond to COVID-19, school administrators, teachers, and parents express appreciation for the straightforward information that the panel provides.
“Because of our academic standing and rigorous use of data, and our professional commitment to public health, our panel has emerged as an independent source of trusted information,” he says.
