Assessing classroom and laboratory spread of COVID-19 in a university after elimination of physical distancing.

The objective of this study was to assess COVID-19 classroom transmission in the university setting when physical distancing was eliminated. Data was collected in fall 2021 at a private university. Universal masking, robust contact tracing, vaccination requirement, and enforced testing were in place. Exposures were classified as classroom versus non-classroom. ANOVA and chi-squared tests were used to identify significant relationships between predictors and COVID-19 test result. Logistic regression was conducted to investigate the relationship between exposure type and test result. A total of 162 student cases were identified with 1,658 associated close contacts. One-third of contacts (31.1%, n = 516) only had a non-classroom exposure, 63.8% (n = 1,057) only had a classroom exposure, and 5.1% (n = 85) had both. Close contacts were significantly more likely to test positive if they had a non-classroom exposure (60 of 601; 10.0%) compared to a classroom exposure (1 of 1057; 0.1%) (OR 58.8, CI 18.5-333.3, p < 0.001). Removing physical distancing in classrooms that had universal masking did not result in high rates of COVID-19 transmission. This has policy implications because eliminating physical distancing does not greatly increase transmission risk when universal masking is in place.