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A team of researchers developed a model to simulate potential COVID-19 transmission in elementary and high schools, as well as households.
Author Beth Duff-Brown Published on July 8, 2021 March 22, 2024It's been a rough year for school children around the world. The United Nations estimates more than 168 million children missed out on in-classroom learning as schools remained largely closed for almost an entire year. In the United States, all 50 states recommended or mandated public school closures, affecting at least 124,000 schools and 55.1 million students.
As of April 2021, about 40% of U.S. public school students were still unable to attend schools in person full time -- leading public health officials, parents and educators to worry that school children would fall behind both academically and developmentally.
Now, as millions of children and teens prepare to go back to school this fall, many parents are wondering whether it's safe -- and if COVID-19 precautions should still be in place to protect their kids.
To inform public policy on the opening debate, a team of researchers at Stanford University, Harvard University, Massachusetts General Hospital and University of Maryland developed a model to simulate potential COVID-19 transmission in elementary and high schools, as well as households.
In a study published June 11 in the Annals of Internal Medicine, the researchers found that with controlled transmission of COVID-19 in communities and adherence to school-based prevention measures -- such as masking and physical distancing -- elementary schools could open with few in-school transmissions. For high schools and elementary schools in communities where COVID-19 rates are high, regular screening of students and staff without symptoms can reduce risk.
"Debates around school reopening have been incredibly contentious because schooling has such central importance to students, families and society, but also because evidence on safety in schools during the pandemic has been incomplete and sometimes contradictory," said Stanford Health Policy's Joshua Salomon, PhD, a co-author of the study.
For example, the researchers noted that some studies have detected little transmission occurring within schools -- yet coronavirus cases in schools have also been documented in other well-regarded studies.
Despite the contradictions, there is hardly any doubt about the benefits of in-person education. There have been reports of increased risk for poor mental and emotional health among children and parents in relation to remote schooling.
"Returning to safe, full-time in-person schooling for every student in the fall -- and keeping schools open and safe -- should be a national priority. Our main motivation in undertaking this study was to define the conditions and actions that are needed to make that possible," said Salomon, a professor of medicine, senior fellow at the Freeman Spogli Institute for International Studies, and director of Stanford's Prevention Policy Modeling Lab.
The researchers simulated settings based on average U.S. classrooms, with elementary schools of 638 students from 500 households, and high schools of 1,451 students from 1,225 households. They allowed for daily COVID-19 cases to vary between 1 and 100 per 100,000 students, faculty, staff and adult household members. They then focused on the risk that transmission would occur on a school campus and spread to household members -- a less explored area of research.
They found that community transmission rates are major drivers of in-school transmission. Whereas elementary schools are likely to experience risks of infection outbreaks that reflect community rates, high schools could fuel ongoing community transmission.
However, preventive measures in schools, such as masking, distancing and ventilation, can mitigate the impact of community transmission. The simulation showed that schools with the resources to effectively implement mitigation measures saw fewer infections transmitted in schools on average, and substantially fewer chances of worst-case outcomes, including large outbreaks.
"We predict that most in-school transmission will occur in the classroom during sustained contact and interventions that reduce classroom transmission can be highly effective, including distancing, masking or reducing class sizes," the researchers concluded. The paper emphasizes that, even in the event of a fall COVID-19 resurgence, staff vaccination markedly decreases risk of transmission and illness.
The study also reports two major benefits of weekly screening for students and staff without symptoms -- less risk that sick people will come to school and infect others, and better real-time information on transmission rates in schools.
Salomon and his colleagues are looking ahead to the continuing rollout of COVID-19 vaccination for adults and teenagers to provide a major boost to safe school reopenings in the fall, especially as new, more infectious variants of COVID-19 emerge.
"Our findings show that safe reopening of schools should be possible under a range of different circumstances, with proper precautions in place," said Salomon. "We hope this information can help decision-makers take proactive measures to ensure that all schools can offer safe in-person learning this fall."
