In a typical year, mid-March is spring break season at Duke University. This, however, is 2021. Not only was the vernal holiday essentially canceled, but a recent outbreak of the coronavirus has forced students into what might be considered the antipode of a week spent partying on the beach: seven days in an administration-mandated quarantine, as officials scramble to curb fraternity party-fueled virus spread on campus.

In a letter to students on Saturday, three leaders of the university in Durham, N.C., outlined the new “stay-in-place” order and described a dire situation: In just one week, more than 180 students tested positive for the coronavirus and 200 others were in quarantine because they had close contact with an infected person.

“This is by far the largest one-week number of positive tests and quarantines since the start of the pandemic,” wrote John Blackshear, the dean of students; Gary Bennett, the vice provost of undergraduate education; and Mary Pat McMahon, the vice provost of student affairs.

The university’s move comes at an uncertain time in the pandemic. After the coronavirus interrupted American life last March — forcing schools, Duke included, to abruptly switch to virtual learning — many corners of the country seem to be emerging from 12 months spent inside or socially distanced. With nearly 70 million people at least partly vaccinated against the virus, the end of the pandemic is in sight.

However, public health leaders have cautioned states — including North Carolina — that it is still too soon to relax restrictions. The Duke order is one of the strictest recent university actions, and it resembles the shutdowns that some colleges instituted in the fall, when returning students sent case numbers soaring. Several studies have found that when campuses become hot spots, the virus often radiates into surrounding communities, seeding more infections.

“If this feels serious, it’s because it is,” Blackshear, Bennett and McMahon wrote in their March 13 letter. “This stay-in-place period is strongly recommended by our medical experts.”

The restrictions will last until at least the morning of March 21 and affect about 6,000 undergraduate students. Graduate and professional classes will continue as planned.

All in-person classes must be held online, students in university housing must remain in their rooms “at all times except for essential activities,” and students living off campus are not allowed on campus except for coronavirus testing, to seek medical care at the student health center and to pick up food.

The worsening outbreak already has affected Duke’s legendary basketball program. The Blue Devils had to withdraw from their conference tournament last week after someone on the team tested positive, following a disappointing season that ended with them missing the NCAA tournament for the first time since 1995.

School spokesman Michael Schoenfeld said in a statement that the new cases “are almost all linked to unsanctioned fraternity recruitment events that took place off campus” and are “the direct result of individual behavior in violation of Duke’s requirements for in-person activity.”

“Those who are found responsible for organizing and hosting these events will be held accountable through the student conduct process,” he added.

In a March 10 bulletin, school officials warned that the majority of newly infected students were affiliated with fraternities or sororities or were male students in their first years. Many of the cases were linked to “the off-campus rush activities and parties hosted by individuals connected to Durham Interfraternity Council,” the officials wrote, referring to a newly formed organization uniting fraternities that have separated from the university.

The school said it is investigating the parties and events.

In an emailed statement to The Washington Post, the Durham Interfraternity Council’s leaders said they were “disappointed that some individuals within fraternities violated the expectations we established for virtual recruitment.”

They said they support the university’s quarantine and will “hold accountable anyone who violates the Duke Compact by reporting them to the University.”

The Durham Interfraternity Council formed following intense nationwide criticism of Greek life, which has long held a high profile on U.S. college campuses — and has a history of sexual assault and White exclusivity. Last month, the organization’s president told the school newspaper, the Duke Chronicle, that it would address issues such as “sexual assault, diversity, inclusion and racial inequality.”

But on Sunday, it drew the ire of Abolish Duke IFC & Panhel, the group working to rid the university of Greek life. The group wrote that the alleged activity by members of the Durham Interfraternity Council is a “flagrant violation of public health guidelines” and “is just one more example of the cycle of harm that fraternities and generational privilege impose on our communities if left unchecked.”

As news of the restrictions spread, the Chronicle reported a sense of anxiety on campus, with students lining up to buy toilet paper and snacks.

“This almost reminds me of what happened a year ago,” one said.

By Sunday evening, with the campus nearly 20 hours into its shutdown, a Facebook page that publishes anonymous comments from Duke students featured dozens of posts alternately cracking quarantine jokes, complaining about the new rules and criticizing fraternity members.

“Stop throwing superspreader events and endangering the lives of elderly staff, and getting the rest of us locked down,” one commenter wrote.

Another asked: “On-campus students suffer the consequences of your actions. Was any of it worth it?”

Correction: A previous version of this report misstated the scope of the university’s quarantine order. The order affects only undergraduate students, not graduate or professional students. The story has been updated.