A new study finds that teachers in the United States may be more important drivers of COVID-19 transmission in schools than students.
The paper released Monday by the U.S. Centers for Disease Control and Prevention studies nine COVID-19 transmission clusters in elementary schools in the Atlanta suburb of Marietta in December and January, That included one cluster where 16 teachers, students and relatives of students at home were infected.
In only one of the nine clusters was a student clearly the first documented case, while a teacher was the first documented case in four clusters. In another four, the first case was unclear. Of the nine clusters, eight involved probable teacher-to-student transmission. Two clusters saw teachers infect each other during in-person meetings or lunches, with a teacher then infecting other students.
“Educators were central to in-school transmission networks,” the authors wrote.
The findings line up with studies from the United Kingdom that found teacher-to-teacher was the most common type of school transmission there, and a German study that found in-school transmission rates were three times higher when the first documented case was a teacher.
Other research has suggested that there’s low transmission of viruses and that schools should reopen, a message that President Joe Biden’s administration has been pushing in recent weeks to mixed success. Marietta, like all but a handful of Georgia districts, has been offering in-person classes since the fall.
All the Marietta clusters also involved “less than ideal physical distancing,” with students often less than 3 feet apart, although plastic dividers were placed on desks.
“Physical distancing of greater than 6 feet was not possible because of the high number of in-person students and classroom layouts,” the authors wrote.
In seven cases, transmission may have taken place during small-group instruction sessions where teachers were close to students. Although the authors said they observed students wearing masks, interviews found that “inadequate mask use” by students could have contributed to the spread of infection in five clusters.
The CDC again advised that schools need to pursue “multifaceted” strategies to prevent the spread of the virus, including cutting down on teacher-to-teacher meetings, making sure masks are worn correctly and increasing physical distancing, especially during mealtimes when people can’t wear masks.
The authors wrote that Marietta has already made changes, including reducing in-person contact among teachers. The district’s superintendent wasn’t immediately available for comment.
The study also said that in addition to those strategies, it might be desirable to vaccinate teachers to protect educators, cut down on in-school transmission and keep schools operating in person, although the CDC restated that teacher vaccination is “not a requirement for reopening schools.”