Last week was the University of Illinois’ best week in controlling the spread of COVID-19, recording fewer than 100 new cases for the first time since the summer.

In all, during the week that ended on Friday, 85 people on campus tested positive for COVID-19 for the first time, with another 54,000 tests administered during that time period.

Since classes began, 2,400 students, faculty and staff have tested positive for the virus on campus. The bulk of this came in the second week of classes, when nearly 900 new people tested positive within a one-week span.

The University then entered a two-week lockdown, and the testing protocol underwent several changes. Graduate students, faculty and staff were only required to test once a week, and undergraduate students in high-risk areas were asked to test three times a week.

For the five weeks afterward, the University found a steady load of around 200 new cases per week, which was lowered from the lockdown, but not the steady decrease campus officials hoped for.

“The numbers have not come down as much as we would like,” said Rebecca Smith, epidemiologist and co-leader of the SHIELD Target team.

The gradual slide in cases is coming from two factors: math and socializing. There’s still an observable bump in cases on Mondays and Tuesdays, which the SHIELD team attributes to weekend socializing on Thursdays and Fridays.

Additionally, the statistics phenomenon of “backwards bifurcation” is working against campus efforts to completely control the spread.

“It says basically, if you get past a certain tipping point, it takes a lot more to get back to where you want to be,” Smith said. “So, the amount of effort to get things under control depends on where you’re starting from. And unfortunately, I think that big spike was enough to push us over a tipping point.”

Double-digit new cases in a week is a pretty good trend, but there’s still a long way to go.

According to Smith, there are currently 18 residences in private and off-campus housing that have earned the high-risk designation for in-house COVID-19 outbreaks.

Around 95% of campus cases have been undergraduates, which campus officials say has maintained throughout the semester.

Illinois’ testing initiative began on July 6, and 48,605 individuals have submitted saliva samples for testing on campus. Of them, 2,775 have tested positive. The on-campus infection rate stands at 5.7%.

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