O'FALLON, Mo. -- With more than 300 University of Missouri students infected with the coronavirus and cases spiking in the surrounding community, Columbia's city health director on Friday announced a new order that limits crowd sizes and requires bars to close early.

Stephanie Browning, who leads the health department for Columbia and Boone County, said at a news conference that new cases of COVID-19 "are increasing exponentially, it feels like." She cited a county test positivity rate of 44.6% last week as evidence of "widespread community transmission."

The 44.6% positivity rate is roughly four times the county's 11% rate before students returned to classes on Aug. 19. It is nearly eight times the seven-day rolling average rate for the U.S. as of Thursday, which was 5.9%, according to data from The COVID Tracking Project.

Effective Friday, public gatherings must be limited to no more than 20 people, with some exceptions. Bars and restaurants must cut off alcohol sales at 9 p.m. and close no later than 10 p.m.

"I'm certain they're worried about the economic impact of this," Browning said. "We all are."

Businesses found in violation could face prosecution. Browning said the order was deemed necessary because people gathering at bars are failing to adhere to previous guidance issued by the health department.

"What we're seeing in our violations is they're coming late at night," Browning said. "Big groups gathering. They're not wearing their masks, they're not social distancing."

The university's coronavirus dashboard cites 306 active cases among students. University of Missouri System President and MU Chancellor Mun Choi said none of the students who have tested positive were hospitalized. He said the university is not currently considering going to online-only classes, a move made recently by the University of North Carolina-Chapel Hill.

"Going forward, we're going to continue to enforce our policies on the campus and off-campus and ensure that we continue to keep this community safe," Choi said.

Missouri's health department reported 1,418 new confirmed virus cases on Friday, bringing the total since the pandemic began to 80,992 The state also announced 14 new deaths, bringing the statewide total to 1,464. The state has the nation's 10th highest per capita rate of infection, 18.33 per 100,000 residents, according to data compiled by Johns Hopkins University.

Meanwhile, the state has no mask mandate, but several local jurisdictions have their own, including Boone County. Jefferson County, near St. Louis, joined the list Thursday, when the county health board voted 3-2 to require people to wear masks inside businesses and other places where social distancing cannot be maintained.

St. Louis city and county enacted mask requirements last month.

With Busch Stadium in St. Louis devoid of baseball fans because of the pandemic, it may find another use. The Cardinals volunteered the ballpark complex as a voting site for the November election. The St. Louis Board of Election Commissioners is looking into the feasibility.

Cardinals pitcher Jack Flaherty approached the team about the idea after seeing LeBron James' More Than a Vote campaign work with the Los Angeles Dodgers to establish Dodger Stadium as a voting site, the St. Louis Post-Dispatch reported.