(CN) — Teachers are more likely than students to drive the spread of Covid-19 in schools, according to a new study by researchers at the Centers of Disease Control and Prevention. The research adds evidence to previous statements by CDC officials on how to safely reopen schools during the pandemic.
The study assessed Covid-19 transmission clusters across eight public elementary schools in a single Georgia school district. Data was collected in December and January for the schools located in Marietta, a suburb of Atlanta.
Studying a total of nine clusters involving 13 teachers and 32 students, researchers attempted to trace how the coronavirus spread among the groups. In four clusters, the initial case was a teacher; in another four, the first case was undetermined; and in one cluster, the first case had been a student.
Each of the clusters in Marietta were in cases where “less than ideal physical distancing” was being practiced, the researchers say. Due to classroom layouts and the number of students in school, it wasn’t possible to keep individuals 6 feet apart.
Students were blocked by plastic dividers but were sometimes less than 3 feet apart.
Small group exercises that put teachers and students in close contact may have been the source of transmission in seven cases, the researchers found. They also observed “inadequate mask use” that could have played a role in five clusters.
Previous studies have found that children may play a smaller role than adults in spreading the coronavirus.
“Evidence suggests that staff-to-staff transmission is more common than transmission from student to staff, staff to student, or student to student,” said CDC Director Rochelle Walensky, who joined the agency after teaching medicine at Harvard and leading Massachusetts General Hospital’s Infectious Diseases Division.
The CDC’s new study backs Walensky’s statement. “Educators were central to in-school transmission networks,” according to Monday’s report.
To preventing in-school transmission, the CDC on Monday laid out several mitigation measures schools could adopt, including “minimizing in-person adult interactions at school, and ensuring universal and correct mask use and physical distancing among educators and students when in-person interaction is unavoidable.”
The report notes that Covid-19 vaccination “should be considered as an additional mitigation measure to be added when available.” Keeping with a trend of previous statements, however, the agency stopped short of saying that teachers should be required to vaccinate themselves before returning to work.
"Vaccination of teachers is not a prerequisite for the safe reopening of schools,” Walensky said in early February.
While the CDC isn’t mandating that schools reopen, a group of CDC researchers made the case in January with a scientific viewpoint citing evidence “has been reassuring insofar as the type of rapid spread that was frequently observed in congregate living facilities or high-density worksites has not been reported in education settings in schools.”
Still, the viewpoint noted, “some school-related activities have increased the risk of SARS-CoV-2 transmission among students and staff.” After a December 2020 high school wrestling tournament in Florida, 38 people tested positive for the coronavirus but fewer than half of the 130 students, coaches and referees in attendance were tested.
Researchers discovered further transmission through contact tracing, and one death was reported in a contact. Recognizing transmission risks, some states have stopped or postponed athletic programs — but not all.
“Paradoxically,” the researchers note, “some schools have used a fully online model for educational delivery while continuing in-person athletic programs.”
President Joe Biden has also set a goal of “getting a majority of K-8 schools safely open” in the first 100 days of his tenure. Before that can happen, however, schools need basid safety measures like new ventilation systems and Covid-19 testing requirements.
“The teachers I know, they want to work, they just want to work in a safe environment, and as safe as you can rationally make it, and we can do that,” Biden said. “We should be able to open every school, kindergarten through eighth grade, if in fact we administer these tests.”
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