The analysis, published in PLOS Computational Biology, showed that in a classroom with 25 students, anywhere from 0 to 20 students might be infected after exposure based on the small adjustments to transmission rates for infected individuals or environments.
The researchers also tested the effectiveness of 2 different transmission control strategies. The first strategy involved students, teachers, or staff members being told to stay home, being tested using a PCR test, and using control measures in the classroom if symptoms are shown. The second strategy involved the use of rapid tests on a regular basis regardless of whether symptoms are present. When an individual tests positive, there is an intervention to prevent further transmission, according to the study.
The team found that in settings with high transmission rates, the interventions used in the first control strategy in which preventive actions took effect after a positive test result were slower at preventing large outbreaks. Conversely, using rapid tests for screening the whole population and catching infections before symptoms developed led to preventing large outbreaks.
“We found that interventions that only took effect after someone developed symptoms and tested positive were too slow to prevent large clusters; only regular monitoring of asymptomatic individuals could prevent the worst outcomes,” Colijn said in the press release.
Fellow professor Paul Tupper noted that he hopes to use these data on transmission and cluster sizes in schools to estimate key unknowns about COVID-19 in schools, such as the rate of transmission and how much it varies from classroom to classroom.
“We could then see how transmission depends on preventative measures that are put in place, such as mask use, improved ventilation and hand washing,” Tupper said in the press release. “This would inform which interventions, after a case is detected, would be the most effective.”
Tupper additionally noted that their previous work on this subject supports the effectiveness of regular rapid testing in protecting residents of long-term care homes.
“Our results were based on simulations of a classroom, but the same considerations apply to other settings such as workplaces, or communal living settings such as long-term care homes,” Tupper said in the press release.
Regular rapid testing detects COVID-19 soon enough to stop transmission in schools. EurekAlert! July 8, 2021. Accessed July 9, 2021. https://www.eurekalert.org/pub_releases/2021-07/sfu-rrt070821.php