New York University is the latest college to cancel events over a coronavirus surge.

New York University announced Wednesday that it was immediately canceling all “nonessential” gatherings and events both on and off campus, including graduations, holiday parties, study groups and athletic competitions, because of surging rates of new coronavirus cases in the community.

“It’s not a cause for alarm, but it is a cause for concern, caution, and appropriate actions,” the university’s provost, Katherine Fleming, said in a memo to the entire university.

New York University is the latest college in the Northeast or Midwest to cancel in-person gatherings as cases of the coronavirus suddenly climb. The increases are tempering optimism that American colleges can safely continue on their planned trajectories back to normal after the dispiriting remote experiences of last year.

New York University is also among a growing number of colleges that will mandate booster shots to return to campus for the spring semester, in an effort to better control the Omicron variant, which scientists believe is causing vaccine breakthrough infections and is already present on some college campuses.

Cornell University, which reported 930 positive cases this week alone, including some with the Omicron variant, has put its main campus in Ithaca, N.Y., on its highest alert level, Code Red. Cornell moved final exams online and canceled all in-person events as of Tuesday.

Princeton University in New Jersey has also moved finals online, to enable students to leave for home as soon as possible. Among Princeton’s rising cases are “suspected cases of the highly contagious Omicron variant,” Jill Dolan, the dean of Princeton College, the university’s undergraduate school, wrote in an email to students on Tuesday, explaining the sudden shift.

The surges are happening at universities with very high vaccination rates. At New York University, 99 percent of students and faculty are vaccinated. So is 97 percent of the on-campus population at Cornell.

Last week, Middlebury College in Vermont moved to remote instruction for the rest of the semester. On Tuesday, Bowie State University in Maryland moved exams online and told students to leave the residence halls “as soon as possible.” DePaul University in Chicago and Southern New Hampshire University each said this month that they would switch to all remote instruction, at least for a time, when classes resume in January.

Cases are rising rapidly in the Northeast and remain high in the upper Midwest. The Centers for Disease Control and Prevention said on Tuesday that 13 percent of new cases reported in a region composed of New York, New Jersey, Puerto Rico, and the U.S. Virgin Islands involved Omicron. In New Jersey, daily reports of new coronavirus cases are up by 90 percent from two weeks ago, on average; in New York State, they are up by 60 percent.

New York City, where New York University is based, is now averaging about 3,200 new positive cases a day, 70 percent more cases a day than two weeks ago, according to city data. Hospitalizations are also rising, though more slowly, in part because of the city’s high rates of vaccination.

New York University’s letter to the community on Wednesday cited a “considerable acceleration in the rate of new cases” as the reason for the new precautions, which included moving most final exams online. Community members should wear masks, limit eating times in indoor public settings to 15 minutes while remaining socially distanced, and then put their masks back on, the letter said.

The school is monitoring the virus situation and is still anticipating allowing in-person gatherings in January. University administrators have not indicated whether Omicron cases have been detected among students or faculty.

“This is not quite how we expected to end the semester; however, if there is any consistency to the coronavirus, it is its unpredictability,” Ms. Fleming wrote.