School Reopening Safe With Mitigation Strategies, Modeling Study Suggests

By Lisa Rapaport

June 09, 2021

(Reuters Health) - U.S. schools can reopen safely and limit SARS-CoV-2 transmission when community conditions are controlled and mitigation strategies such as asymptomatic screening are implemented, a new modeling study suggests.

For their analysis, researchers developed an agent-based network model to simulate transmission in high school and elementary school communities that included interactions within schools, within households, and between individuals from multiple households. The model was based on typical U.S. school sizes, with 638 students in elementary schools and 1,451 students in high schools.

In simulations, schools could achieve "controlled transmission" in groups of students, educators, staff, or families if reopening resulted, on average, in a less than 1-percentage-point increase in the proportion of the group that was infected, compared with individuals in that group who did remote learning.

Several mitigation strategies may help limit the spread of the virus when schools reopen, including masking, distancing, and reduced class sizes, the researchers report in the Annals of Internal Medicine.

In addition, asymptomatic screening may enable schools to reopen safely when local incidence rates are higher, while still minimizing transmission associated with in-person school.

Asymptomatic screening is highly effective for two reasons, said senior study author Meagan Fitzpatrick of the University of Maryland School of Medicine in Baltimore.

"First, many infections will be caught early in their infectious period, so the infected person will then stay away from the school environment and the probability of transmission is reduced," Fitzpatrick said by email.

Asymptomatic screening is also helpful for providing real-time information about the risk at a particular school, Fitzpatrick added.

"If cases are detected, then additional action can be taken to mitigate risk both at school and for families," Fitzpatrick said. "When no cases are detected, everyone can feel reassured about school safety."

Researchers from the University of Maryland School of Medicine, Harvard University, Stanford University, and Massachusetts General Hospital used a simulation model to assess the risk for.

The analysis looked at a wide range of mitigation strategies including isolation of symptomatic individuals, quarantine of an infected individual's contacts, reduced class sizes, alternative schedules, staff vaccination, and weekly asymptomatic screening. Researchers then projected transmission among students, staff, and families after a single infection in school and over an eight-week period, contingent on local incidence.

While school transmission varied based on student age and local incidence, researchers also found that mitigation strategies such as teacher vaccination, masking, and social distancing all helped reduce the risk.

One challenge, however, is that the risk of transmission remains substantially higher in high schools than in elementary schools, the study team notes. This may be because older students are more susceptible to infection than younger students, and because high schools typically have students change classes and mix with more people throughout the day, Fitzpatrick said.

"Thankfully, vaccination is a very powerful mitigation tool, and it is now available to adolescents," Fitzpatrick said. "If a large proportion of teens in a particular school are vaccinated, it could very well make that school safer than an elementary school."

In support of school reopening, an editorial accompanying the study highlights the mental health toll of remote learning on school-aged children. From 2019 to 2020, the proportion of U.S. emergency department visits related to mental health climbed 24% among children aged 5 to 11 years, and 31% among youth 12 to 17 years, the editorial notes, citing previously released data from the U.S. Centers for Disease Control and Prevention.

Dr. Ted Long of New York City Health + Hospitals writes in the editorial that public schools reopened for in-person learning in the fall of 2020 in the nation's largest school district and found that transmission in schools was uncommon, with transmission rates at or below levels in the community.

Now that more students are getting vaccinated, this will add another layer of protection that makes the risk of reopening schools even lower, Dr. Long writes.

"As we enter the recovery phase of the COVID-19 pandemic, it is crucial to support our children and adolescents who have suffered from lack of educational opportunities and social interaction," Dr. Long writes. "Data show that schools can be reopened safely with preventive measures. We must do everything we can to reopen our schools to ensure that young people emerge from this pandemic healthy."

SOURCE: and Annals of Internal Medicine, online June 7, 2021.