USC researchers simulated the spread of COVID-19 on a university campus, specifically by modeling airborne transmission risks associated with face-to-face classes. Photo/iStock.

With coronavirus cases on the rise again in almost every US state, the big question is: How can we stay safe while we resume normal life, especially in crowded spaces like college campuses? For the past two years, decision-makers have been forced to make decisions about everything from vaccination and mask requirements to occupancy limits based on ever-changing assumptions about COVID-19.

Now, USC researchers have helped quantify the effectiveness of some of the most debated mitigation strategies by simulating the spread of COVID-19 on a university campus, specifically modeling the risks of airborne transmission associated with face-to-face classes.

The new study, published in the Proceedings of the National Academy of Sciences (PNAS), shows that during the outbreak of the highly transmissible Delta variant, at least 93% of schoolchildren should be vaccinated, with everyone wearing masks indoors to help to prevent an increase in cases. For the original COVID-19 strain, 23% of students should be vaccinated, with everyone wearing masks indoors (or 64% of students not wearing masks).

These insights will help decision-makers during ongoing COVID-19 outbreaks or an outbreak of a similar infectious disease. The simulation model also allows decision-makers to explore “what-if” scenarios related to the spread of COVID-19 in classrooms, varying parameters to see the outcome under different scenarios, such as: B. hybrid classes, current vaccination rates, masking protocols, community infection levels and varying degrees of viral infectivity.

“We’ve found our way around a lot of these things over the past two years, but this gives us a more tangible, data-driven process to bypass.” Bhaskar Krishnamachari.

“I think the hardest thing about the pandemic has been finding the right balance — there’s a tension between having some kind of normalcy to go about our lives and protecting ourselves,” said study co-author Bhaskar Krishnamachari , Professor of Electrical Engineering and Information Technology and Computer Science.

“This paper helps to think more clearly about when we can operate in person with or without masks and when we need to mandate vaccines. We’ve found our way around a lot of these things over the past two years, but this gives us a more tangible, data-driven process to align with. It doesn’t have to be an arbitrary or political decision. That tells us there are nuances scientifically.”

The study, titled “Simulating COVID-19 Classroom Transmission on a University Campus,” was authored by Arvin Hekmati, a PhD in computer science. Pupils; Mitul Luhar, Professor of Aerospace and Mechanical Engineering; Bhaskar Krishnamachari, Professor of Electrical and Computer Engineering and Informatics; and Maja Matarić, Professor of Computer Science, Neuroscience and Paediatrics.

Highly granular data

The research is particularly relevant in the early days of an infectious disease outbreak, when policymakers face the difficult decision of ordering school closures. Using a simulation of the spread of COVID-19 based on real anonymized data from a major university, the researchers projected the impact of different school reopening strategies: total closure, hybrid, in-person; vaccinated and unvaccinated; masked and unmasked.

In a unique study, the model accounts for highly granular data such as lesson plans, classroom sizes, occupancy, ventilation rates, and vaccination rate and effectiveness, and even specific information about classroom interactions, such as the role of language and disease transmission in an enclosed space.

“Nothing has to be made by assumptions; We can quantify every aspect of this epidemic and make the best decision.” Arvin Hekmati.

Results showed that without vaccination, moving 90% of classroom instruction online can reduce new infections by up to 94%, while universal use of masks can reduce new infections by up to 72%.

“With this tool, universities don’t have to make these decisions without knowledge – they can make informed decisions for university policies to protect them for students, faculty and staff,” said Hekmati. “Nothing has to be made by assumptions; We can quantify every aspect of this epidemic and make the best decision.”

opportunity and responsibility

Researchers from the fields of computer science, electrical engineering and aerospace engineering have joined forces to work on this paper, which draws on expertise in both large-scale computational modeling and mechanistic transmission modeling of COVID-19.

“As a university, we have the opportunity and responsibility to study our own community to gain insights to inform the general public,” Matarić said.

“This project was extremely gratifying because it brought together colleagues from multiple departments at the Viterbi School, who enabled the analysis and modelling, which in turn provided insight into the safety policies for university campuses during pandemic conditions.”

To inform the model, Professor Luhar, an expert in modeling indoor airborne spread, analyzed the mechanisms of transmission of COVID-19, taking into account everything from room size to the number of people present and how long they were talking – all this can lead to fluctuations in virus emission rates from teachers and students.

For example, during lectures, lecturers speak significantly more often than students, which could affect transmission rates. “Providing these facts in the model made it very compatible with universities and classrooms,” said Hekmati.

In future work, the team hopes to expand their research into a tool that could be used by campus administrators at large universities and work campuses. Although this model was designed specifically for classrooms, there are many modular aspects that could be tweaked to extend to other types of environments, the researchers said.

“Nothing gives us more satisfaction as engineering researchers than having a positive impact on society,” said Krishnamachari, who also serves as an advisor to Hekmati. “Most of us had this dream when we started engineering school that we were doing meaningful work that helps others and I’m really happy for Arvin to have worked on a project where he had such a positive impact can see impact.”

Released May 26, 2022

Last updated on May 26, 2022