People make their way along the Strip, the University of Alabama's bar scene, on Aug. 15 in Tuscaloosa, Ala. On Monday, the city ordered bars and bar service at restaurants to close for a two-week period in an effort to combat the coronavirus. (Vasha Hunt/AP)

The university announced Friday that 481 students on its flagship campus in Tuscaloosa tested positive this week, bringing the total number of infections reported there in the past two weeks to 1,043. The university has also reported more than 150 cases among students at its Birmingham campus and 10 at its Huntsville location.

The outbreak represents one of the largest coronavirus clusters reported at any academic institution since the start of the new academic year, painting an alarming picture for densely populated campuses across the country and the communities that surround them.

Tuscaloosa Mayor Walt Maddox (D) said the spike in campus infections could threaten both the city’s health-care system and the local economy, which is heavily dependent on the 38,000-student university.

“We don’t know what the community spread may be,” Maddox told The Washington Post on Saturday, adding that it could take two weeks or more to get a clear read on the extent of the outbreak from testing and hospitalization data.

“We’re also talking about thousands of jobs that are at risk in our community if there aren’t in-person classes,” he said. “There’s a lot on the line.”

To slow the spread of the virus, Maddox announced on Monday a shutdown of bars and suspension of bar services in restaurants for two weeks. The university also placed a moratorium on in-person student events and restricted access to Greek houses. University workers were testing students regularly and conducting contact tracing, and ample space remained to isolate those who tested positive, officials said.

Before coming to campus, students were required to complete testing and training, and to report their daily health conditions, according to Monica Watts, a university spokeswoman. There was no evidence that the virus was spreading in classrooms, and no students were currently hospitalized, she said.

“Our top priority at The University of Alabama is the safety of our students, faculty and staff,” Watts told The Post in an email. “As we prepared for the fall semester, we developed one of the most comprehensive testing and entry programs in the nation. We continue to update the plan and fine tune our strategies daily.”

Maddox, whose daughter attends the university and lives on campus, said university officials were “doing everything humanly possible” to contain the virus. He said there was no “line in the sand” for shuttering the campus if infections continued to climb but cautioned it would be “extremely difficult if not impossible to keep moving forward” if the university ran out of room to isolate sick students.

“There’s not a playbook for us to review to know the moment that we need to take a step back,” he said.

Rising cases statewide in Alabama may have contributed to the outbreak on campus. Infections in the state erupted in July and were trending upward again after dipping slightly in August. The rolling average for new daily reported cases has jumped more than 34 percent over the past week, according to The Washington Post’s tracking, with a test positivity rate of 14 percent, far higher than public health experts recommend for reopening businesses.

The situation at the University of Alabama was “a very cautionary tale” but “somewhat unique in that the surrounding region was so bad to start off with,” said Howard Forman, a public health professor at Yale University.

“The concern, of course, is for the students. But much more so for the staff and faculty who work with them and the surrounding communities,” Forman told The Post in an email. “If these regions were hoping to get this under control, this hurts.”

The rapidly spreading infections, along with the extreme steps the university has taken to contain them, have already led some students to change their plans for the academic year. The student newspaper reported this week that one freshman decided to drop out after officials abruptly relocated students in her dorm to another building to make rooms available for isolation.

“I can’t afford to go here if they’re gonna send us home,” the student, Amalia Halpin, told the Crimson White. “It’s super unfortunate, but I had to drop out of college for it. This has been an absolute disaster.”

Other large institutions, including the University of Kansas and North Carolina State University, have reported significant virus outbreaks in recent days, prompting some to warn that they may shut down campus if cases spiral out of control.

Like Alabama, most universities have rolled out strict measures to curb the virus spread, including mandatory masks and regular testing. But administrators and health experts alike have expressed concerns about universities’ ability to regulate off-campus activities, such as large parties, that could create ideal conditions for transmission.

“We need to remain humble about what we know and don’t know” about campus outbreaks, said Forman, of Yale. Undergraduate campuses face particularly high risks because of a combination of factors, he said, including crowded housing and high concentrations of young people who appear to transmit the virus asymptomatically at a higher rate than older adults.

“These items do make spread much more likely,” Forman said. “If a young person sees little personal risk, has no symptoms, and is driven by desire for social interactions, they will potentially spread much more quickly than others.”

In addition to Alabama, states across the Midwest continued to report substantial upticks in coronavirus cases.

Infections have trended upward over the past week in Iowa, Kansas, Nebraska, Minnesota and the Dakotas, and have flatlined in Illinois and Wisconsin, according to The Post’s tracking. North Dakota reported a single-day record of 374 cases on Saturday. In Iowa, daily infections have topped 1,000 for three days straight.

Nationwide, more than 46,400 infections were reported Saturday. The pandemic death toll in the United States was nearing 180,000.

Meryl Kornfield contributed to this report.