Harvard students hauled brown cardboard boxes across campus and scrambled to book last-minute flights out of Boston Tuesday after the Ivy League school told its students that they should stay away after spring break next week and take their classes online for the rest of the semester.

At MIT, students and faculty practiced using teleconference technology as administrators on Tuesday called off in-person classes and told all their undergraduates to leave campus by noon on March 17. When MIT’s spring break ends on March 30, classes will be held remotely.

Across New England and the United States, colleges and universities stepped up their efforts to contain the spread of the coronavirus, with more than a dozen transitioning to virtual classes and essentially shutting down their campuses to student activities.

Several other Boston-area colleges announced Tuesday that classes will be moving online and students must move out of campus housing.

Tufts University in Medford will remain open, but all classes will be conducted virtually starting March 25, president Anthony Monaco said in a statement.

“It is imperative that we take steps as individuals and as a community to help limit the spread of the coronavirus,’’ Monaco said.

Spring break will be extended until that date, but undergraduates must vacate campus housing by Monday, March 16, the statement said.

Emerson College and Suffolk University in Boston, Babson College in Wellesley, and the Olin College of Engineering in Needham also announced they will complete the semester with virtual learning.

Earlier in the week, Amherst College, Smith College, and Middlebury College also instructed students to stay away from campus after spring break.

“The decision was not made lightly,’’ Harvard president Larry Bacow said in his message to his school’s community on Tuesday. “The goal of these changes is to minimize the need to gather in large groups and spend prolonged time in close proximity to each other in spaces such as classrooms, dining halls, and residential buildings.’’

The last time Harvard took such drastic measures, officials noted, was in the 1940s, during World War II, when the campus was given over to military training. But amid fears that the coronavirus will continue to spread, universities find themselves in a vulnerable spot.

MIT said a recent visit to campus by a recruiter who had contracted the virus illustrated the risks — and the need for more aggressive precautionary measures. MIT officials said a recruiter from Mastercard Advisors who visited the university’s business school in late February has since tested positive for Covid-19.

Mastercard alerted MIT this past weekend and provided the names of five MIT Sloan students and two staff members who met with the recruiter on Feb. 26-27 in a conference room on campus, according to MIT Medical’s website.

The affected individuals have been interviewed by MIT Medical, the school’s health service, and are reportedly in good health and under observation.

“This ended up being a low-risk situation for our community,’’ L. Rafael Reif said in a message to the university. “But it might have turned out differently, so we consider this a cautionary tale.“

MIT expects most undergraduates to move out of their dormitories by Tuesday. The university will consider exceptions for some international students and those who may not have a safe place to go.

In Cambridge on Tuesday, MIT and Harvard students were stunned and flustered as the reality sank in: Returning from spring break was no longer an option.

Just before MIT announced its plans, a group of students gathered on the green in front of the university’s iconic domed building and hoisted up a hand sanitizer station.

Shayna Ahteck, an MIT freshman, took a photo of the crowd and posted the question on social media: “Where were you when the world was ending?’’

Ahteck said she feels conflicted about the move online. The classes she is most excited about this semester are lab and in-person, project-based course, “so they’re effectively canceled.’’ On the bright side, she’s hopeful her midterms will be nixed.

At Harvard, Jack Markert, a 19-year-old freshman from Alabama, scurried through campus with several folded moving boxes that he picked up from the post office. Markert considers himself lucky: He has friends and a sister in Boston willing to store some items for him.

“I have a lot of friends who are international students and who are scrambling right now to see how they’re going to get back to their own countries, and how they are going to be able to get all their stuff packed up,’’ he said. “It’s very chaotic, but we’re making it through.’’

Trevor Ladner, 22, a senior at Harvard, and a friend were delivering their leather-bound senior theses to their professors. They’d imagined a relaxing few weeks before graduation, but now they were trying to figure out how to move all their stuff back home and how they’d manage the online classes.

Ladner said he lives in rural Mississippi where the nearest coffee shop is an hour’s drive and the Internet connection is spotty. At Harvard he also has part-time jobs for the university, which helps offset the tuition costs and loans.

Ladner, who is gay, said he feels supported at Harvard and has a network of friends and places he can freely visit in Cambridge.

“I don’t have to worry about it, I feel safe and affirmed,’’ Ladner said. “I don’t necessarily have that at home.’’

Harvard said it is working with students on financial aid to help defray the expenses of the last-minute move.

In the past few weeks, colleges across the country have rapidly recalibrated their reactions to the coronavirus, as the illness moved from a threat in China to a global problem.

As the virus spread, colleges and universities recalled students on overseas study abroad programs, grounded domestic and international travel for faculty and students, and then restricted large gatherings, including sports events and new student orientations.

MIT on Monday announced that it would transition all large classes — those with more than 150 students — online. But 24 hours later, it moved all instruction online.

The University of Massachusetts Amherst has warned students about traveling to places where the coronavirus cases have spiked and urged them to practice good hygiene. The university has said that it is making preparations for online learning but hasn’t decided whether to move in that direction.

“I understand they’re trying not to cause panic,’’ said Alexandra McCandless, a senior at UMass Amherst. “It feels like the whole response has been muted. . . . I want to know, are we going to be here for graduation?’’

Steve Annear of the Globe staff contributed to this story.