July 21 (UPI) -- Universal masking, social distancing and "simple" ventilation techniques prevented COVID-19 spread among students on school buses in a region with high levels of community transmission, a study published Wednesday by the Journal of School Health found.
During the 2020-21 academic year, at an undisclosed school district in Virginia, there were 39 infectious COVID-19 cases on 15 buses that served 462 students, with 52 quarantined as a result, the researchers said.
However, subsequent testing and contact tracing revealed no transmission linked to bus transportation, with all 52 students testing negative for the virus.
"The pandemic has made it very difficult for public schools to meet the transportation needs of students," study co-author Dr. Dana Ramirez said in a press release.
"Many districts simply do not have enough buses and drivers to allow distancing of three to six feet or skipping of bus rows while still providing rides to all children," said Ramirez, a pediatric emergency medicine physician at Children's Hospital of The King's Daughters in Norfolk, Va.
Since the start of the pandemic, studies have found that COVID-19 spread among children varies by age.
In a study of schoolchildren in Israel published in April, those age 9 and younger had a 10% higher likelihood for becoming infected after they returned to class compared to the period immediately beforehand.
However, those age 10 to 19 had a three-fold higher risk for infection after returning to school compared to when they still were at home, according to the authors of that study.
For this study, the school tested the district's 1,154 students for COVID-19 every two weeks at the start of the school year, on Aug. 24, 2020, regardless of whether they had symptoms of the virus.
As the year progressed, the district began testing students weekly -- again, regardless of symptoms -- through March 19, according to the researchers.
The researchers monitored virus spread on 15 school buses that served 462 students, 235 in grades 1 through 6, 164 in grades 7 through 9 and 63 in grades 10 through 12.
A physical distancing minimum of 2.5 feet was implemented, when possible, but 10 of the 15 buses operated at full capacity, with two students per seat.
There was universal wearing of face masks and simple ventilation techniques -- essentially, the opening of windows, weather permitting.
Bus routes each way ranged from 36 to 60 minutes in the morning, 44 to 74 minutes in the afternoon and 42 to 62 minutes on evening routes, according to the researchers.
The region of southeastern Virginia in which the study was conducted has had more than 120,000 confirmed cases of COVID-19 since the start of the pandemic, with the highest infection rates reported in fall 2020, based on data from Johns Hopkins University.
"With more students returning to face-to-face instruction, safe transportation to school is an equity issue, as many families are unable to drive their children to school each day," Ramirez said.
"We hope ... our data can be of assistance in demonstrating that school buses can safely operate at normal capacity even at high community COVID-19 case loads," Ramirez said.