More than 300 positive cases of COVID-19 were reported in Johnson County over the past four days, as University of Iowa students return to classes.

Dave Koch, director of Johnson County Public Health Department wrote in a press release on Wednesday, that the cases are primarily among young people. He reminded that the state disaster proclamations remain in effect and physical distancing and other measures are required if mass gatherings do occur.

“We want to remind the community that the state disaster proclamation remains in effect and that if large social gatherings “mass gatherings” are to occur, that physical distancing and other public health measures are required,” Koch wrote. “The onus is on you.”

Just this past weekend, downtown Iowa City had experienced lines around bars and crowded bars not adhering to social distancing guidelines set by Gov. Kim Reynolds. UI President Bruce Harreld penned a letter to downtown businesses and organizations imploring them to enforce social distancing and mask wearing.

Tuesday, the University of Iowa Hospitals and Clinics reported 38 percent of tests returned positive, and 361 hospital workers had tested positive since the first cases of the coronavirus appeared in mid-March.

On Monday, the UI released the first number of self-reported cases with 107 students and four faculty members reporting they’d tested positive. Nineteen students in the residence halls are currently in quarantine.

In an interview with The Daily Iowan, CEO of UI Hospitals and Clinics Suresh Gunasekaran said there is no substitute for social distancing, hand hygiene, and face coverings, but refraining from large groups will keep infection rates down. He said public health officials assume that a significant portion of the positive cases is from the returning student population.

“Following all those guidelines that are really important, avoiding congregate settings, avoiding house parties,” he said. “Those kinds of things where you’re really unable to distance and you’re unable to, to protect yourself or those around you.”

According to the release, Johnson County Public Health staff are working seven days a week to educate and inform the individuals who test positive.

“What we are seeing right now is that our actions have consequences,” the release said. “Community health and safety is everyone’s responsibility. Lapses in that responsibility, even by a few, affect all of us. This virus transmits easily and quickly and without the proper precautions in place, one can innocently transmit this to someone else.”

Sabine Martin contributed to this report.