One of the most widely debated topics during the ongoing Coronavirus pandemic is the role of schools as potential sources of COVID-19 infection. The researchers, led by first author Jana Lasser (Graz University of Technology) and Peter Klimek (MedUni Vienna), used cluster analyses from the AGES (Austrian Agency for Health and Food Safety) to create a model for calculating the most effective measures for making schools as safe as possible during a pandemic. To do this, they used data from the autumn of 2020 and the modelling is based on the parameters of the Delta variant.
Infection rate lower in elementary schools than in high schools
There are a range of measures available to prevent infection, including masks, ventilation, teaching in shifts, testing, and now vaccination. "We have seen that a single measure is not enough to control infections at a school," explains complexity researcher Jana Lasser from TU Graz, "a combination of two or three such precautions offers greater protection. And incidentally, regular ventilation has been found to have an above-average impact."
But the social structures of the different types of schools also play a role. For example, elementary school classes with permanently assigned class teachers have different, less risky contact structures than high school classes with multiple teachers, leading to more mixing and increased risk of infection in such schools.
The researchers found that two safety precautions achieve the same level of protection in elementary schools as three such measures in high schools, for example masks and ventilation plus additional testing. Given the current vaccination rate among teachers and pupils in Austria, this is sufficient, even assuming that none of the measures are perfectly applied. "This is where we see the value of the so-called Swiss cheese model," Klimek explains, "none of these measures on its own provides 100% protection against infection but far greater protection is possible if several measures are combined."
However, the results also show that optimal protection depends on the preventive measures being consistently applied. Small clusters can spread extremely quickly and then reach a point where they are virtually impossible to contain, the researchers write.
The calculation model was also adapted to the parameters of the current Omicron variant. Much more stringent packages of measures, combining all the above-mentioned options, are needed to contain Omicron than were necessary for the Delta variant. The calculations will also be used to work out the optimal packages of measures for schools in the autumn of 2022, should Austria experience another wave of infections.
Service: Nature Communications
"Assessing the impact of SARS-CoV-2 prevention measures in Austrian schools using agent-based simulations and cluster tracing data."
Jana Lasser, Johannes Sorger, Lukas Richter, Stefan Thurner, Daniela Schmid, and Peter Klimek