Simple techniques on near-capacity school buses prevent spread of SARS-CoV-2
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Universal testing and contact tracing failed to find evidence that near-capacity school buses were the source of SARS-CoV-2 transmission at a school in Virginia, researchers reported.
“We realized early on that data were showing that schools are safe when simple techniques are used to stop disease spread, even when community disease spread is high,” Dana Ramirez, MD, an associate professor of pediatrics and pediatric emergency medicine at the Eastern Virginia Medical School and Children’s Hospital of The King’s Daughters in Virginia, told Healio Primary Care.
“My co‐authors and I also noted that there wasn’t much data out there about school buses,” she said. “Additionally, many school districts do not have enough bus drivers and buses if they are unable to operate the buses at full capacity. Many families are simply unable to drive their children to school each day, making bus transportation crucial.”
Ramirez and colleagues analyzed data on 1,154 students in grades one to 12 at an independent school in Virginia. They conducted pooled saliva-based testing every 2 weeks from Aug. 24, 2020, to Feb. 4, 2021, and then weekly testing until March 19. If a test came back positive, a confirmatory nasal swab test was performed. The nearly 7-month study was performed during the highest community SARS-CoV-2 transmission period, according to the researchers.
Fifteen school buses transported 462 students to the school. The duration of the bus trips ranged from 36 to 74 minutes. The buses were filled near capacity, with two students in each seat. “Simple mitigation” techniques were used to prevent SARS-CoV-2 transmission, such as physical distancing of 2.5 feet or more, universal masking and spaced window openings, the researchers wrote.
“Buses were required to provide a 1-inch window opening in the middle two windows and the two windows in the last row of seats on the bus,” Ramirez and colleagues wrote in the Journal of School Health. “Buses were not loaded back to front, but older students were assigned to back rows while younger students were assigned to the front half of the bus. Students sat in the first row of the bus behind the bus driver which was spaced 4 feet from the driver, without any barrier between the students and the driver.”
According to the researchers, 39 individuals rode a school bus while infected with SARS-CoV-2, including 37 students, one driver and one aide. This resulted in 52 additional people being quarantined. However, universal testing and contact tracing failed to identify student-to-student transmissions, adult-to-student transmissions and student-to-adult transmissions.
A larger study with more students and schools would likely yield low disease transmission rates, “but might not be zero as it was in this study,” according to Ramirez.
She encouraged primary care physicians to share the following school bus transportation strategies with parents and school districts:
- Use every row on a bus, assign seats and seat siblings together when possible.
- Partially open windows, even if the weather is not favorable.
- Establish an environment that keeps children and staff from coming to school sick.
- Ensure school bus passengers and drivers are masked.
- Use multiple prevention strategies in tandem.
“As schools reopen for in-person learning, safe bus transport is vital to maximizing student and staff health, but buses must operate at close to maximum capacity in order to provide transportation equitably to all students,” Ramirez and colleagues wrote. “The model offered may assist school administrators in planning transportation operations.”
Perspective
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Adam L. Hersh, MD, PhD
Bus transportation is a critical component of school operations, and it is every bit as essential to ensure that we implement effective prevention strategies in this setting as in classrooms.
It is likely that another study like Ramirez and colleagues’ or a larger one conducted during last school year would have had similar results. Their findings fit into the broader body of evidence that shows that the likelihood of SARS-CoV-2 transmission with high mask compliance and other prevention strategies in place in school environments is low (many studies have estimated about 1% or lower).
However, it is uncertain whether this low transmission rate will hold during the upcoming school year for two main reasons. First, the delta variant is substantially more transmissible. Second, in some school settings, the extent to which masks will be required or used at all remains uncertain. It will be critical to continue to perform epidemiologic studies like this one in school settings as we enter the new school year to best develop and implement prevention strategies that keep our schools open and safe.
Associate program director, pediatric infectious diseases fellowship training program, University of Utah Health
Member, AAP, Pediatric Infectious Diseases Society, Infectious Diseases Society of America
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