What role do teachers play in Covid-19 spread at schools? CDC warns they could be ‘central’ drivers
Teachers may play a central role in transmitting coronavirus in schools, according to an investigation. Researchers identified nine clusters of Covid-19 cases involving 13 educators and 32 students at six out of eight elementary schools studied in a Georgia school district. A cluster was defined as at least three linked cases of coronavirus. Two of the biggest clusters involved probable educator-to-educator transmission during in-person meetings or lunches, which was followed by educator-to-student transmission in classrooms and resulted in approximately one-half (15 of 31 or 48%) of school-associated cases.
According to the US Centers for Disease Control and Prevention (CDC), which conducted the analysis, the findings reveal that initial infections among educators played a substantial role in in-school coronavirus transmission and subsequent chains of infection to other educators, students, and households, highlighting the importance of preventing infections among educators in particular. “Educators might play a central role in in-school transmission networks. Preventing SARS-CoV-2 infections through multifaceted school mitigation measures and Covid-19 vaccination of educators is a critical component of preventing in-school transmission,” recommend authors.
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From December 1, 2020-January 22, 2021, the CDC, Cobb and Douglas Public Health (CDPH), and the Georgia Department of Public Health (GDPH), investigated the Covid-19 spread in eight public elementary schools in a single school district. Coronavirus cases among educators and students were either self-reported or identified by local public health officials.
Close contacts of persons with a Covid-19 case received testing. Among contacts who received positive test results, public health experts assessed epidemiologic links, probable transmission directionality, and the likelihood of in-school transmission.
During the study period, about 2,600 students (approximately 80% of the district’s elementary school students) and 700 staff members attended elementary school in person. During this period, Covid-19 incidence (7-day moving average number of cases per 100,000 persons) in Cobb County, Georgia, increased almost 300%, from 152 to 577 cases.
“An educator was the index patient in four clusters, a student was the index patient in one cluster, and in four clusters, whether the index patient was the student, the educator, or both (that is, two index cases occurred) could not be determined. Eight clusters involved at least one educator and probable educator-to-student transmission,” explain authors.
Additionally, 69 household members of persons with school-associated cases were tested, and 18 (26%) received positive results. Significantly, all nine transmission clusters involved less than ideal physical distancing, and five involved inadequate mask use by students, with teachers “central to in-school transmission networks,” say experts. “These findings suggest that in-school transmission can occur when physical distancing and mask compliance are not optimal,” writes the team.
Public health investigators identified several mitigation challenges. While plastic dividers were placed on desks between students, students sat less than three feet apart. Physical distancing of more than six feet was not possible because of the high number of in-person students and classroom layouts. In seven clusters, transmission among educators and students may have occurred during small group instruction sessions in which educators worked close to students.
The school district mandated in-classroom mask use except while eating, and both reported and observed compliance during site visits was high. However, information obtained during interviews indicates that specific instances involving lack of or inadequate mask use by students likely contributed to the spread in five clusters. Students ate lunch in their classrooms, which may have facilitated spread, the findings state.
The researchers recommend multifaceted mitigation measures in schools, including the promotion of Covid-19 precautions outside of school, minimizing in-person adult interactions at school, and ensuring universal and correct mask use and physical distancing among teachers and students when in-person interaction is unavoidable.
“Although not a requirement for reopening schools, adding Covid-19 vaccination for educators as an additional mitigation measure, when available, might serve several important functions, including protecting educators at risk for severe coronavirus-associated illness, potentially reducing in-school transmission, and minimizing interruptions to in-person learning, all of which have important implications for educational equity and community health,” advises the CDC.