As coronavirus cases explode nationally and hospitals continue to fill, Rutgers University this week said it would push back most in-person instruction to the end of January and delay students’ move back to campus.

New Jersey’s flagship state university with more than 70,000 students also said it would require all eligible students and employees to get a coronavirus booster shot.

“Every tool we can put in place, we are going to put in place,” said Tony Calcado, Rutgers’ executive vice president and chief operating officer.

But Pennsylvania State University, with 97,000 students, nearly half of them at its anchor in State College, isn’t requiring the booster, though strongly encouraging it. (The school also didn’t require the initial vaccine.) And, the university plans to bring students back to campus as planned this weekend and start in-person instruction next week.

“With our high vaccination rates and the fact that we haven’t seen the disease spread in our classrooms, we believe we can safely return to in-person learning, which is important for our students,” said Kelly Wolgast, director of Penn State’s COVID-19 Operations Control Center.

» READ MORE: Colleges weigh requiring COVID-19 booster shots as cases surge

As another semester begins under the shadow of COVID, colleges have continued to differ in their approaches, with some implementing far more changes and restrictions than others.

Of 17 area universities surveyed, 12 — the University of Pennsylvania, La Salle, Drexel, Princeton, Swarthmore. Haverford, Villanova, Widener, Ursinus, St. Joseph’s, Bryn Mawr, and Rutgers — said they would require eligible students and, in some cases, employees to get a booster. In addition to Penn State, Rowan, West Chester, Temple, and Thomas Jefferson are not requiring the booster, although strongly encouraging it.

Eight of the 17 — Drexel, Penn, Temple, Rutgers, Widener, La Salle, Swarthmore, and Thomas Jefferson — said they would delay most in-person instruction until later in January. Some schools, including Princeton, also said they would push back students’ return to campus to give the more contagious omicron-driven surge a chance to move through.

“While this is an uncertain situation, the data modeling suggests that we must take steps to prepare for a potential surge of cases in January,” Penn officials wrote Dec. 23 in announcing most classes would begin virtually Jan. 12 and that student move in would be delayed a week.

» READ MORE: The college fall semester begins as another pandemic chapter unfolds

While Temple is allowing students to move back starting Jan. 8, it will keep most instruction online through Jan. 21. Like at many other schools, students who are moving in are required to be tested for COVID-19.

Some colleges are planning other steps, including restricting dining hall use, limiting food and beverages in classrooms, prohibiting spectators from attending sports games, and recommending that students and staff use more protective masks than cloth coverings.

Princeton announced it would ban students in all but extraordinary circumstances from leaving Mercer County once they return to campus until mid-February.

“Limiting personal travel by students at the start of the semester is important because most of the case clusters among students during the pandemic have been traced back to such travel,” said Princeton spokesperson Michael Hotchkiss.

While Drexel has delayed the start of in-person classes until Jan. 18, it is not restricting spectator attendance or closing dining halls, said Marla J. Gold, chief wellness officer and senior vice provost for community health at Drexel.

“In a highly vaccinated, highly boosted community, there comes a time where we have to see how it goes,” she said.

The university’s testing sites are seeing more infections in a day than they’ve seen in a week, but most cases are mild and data suggests that the omicron wave should begin to decrease in a couple of weeks, she said.

“If COVID throws us another curveball, we’ll move with it,” she said. “That’s how it is every day here.”

» READ MORE: Rutgers becomes first college in the region, possibly the nation, to require students to get COVID-19 vaccinations

At Rutgers, officials decided on remote instruction and a booster requirement after watching cases mount in New Jersey and hospitals fill, and saw that data showed the difference in severity of illness between the vaccinated and unvaccinated. Its campuses are in three cities — New Brunswick, Camden, and Newark — and officials knew that any decision would impact not only students and staff but also their families, he said.

“We’re heartened when Rutgers prioritizes the safety of our community,” said Rebecca Givan, president of the Rutgers faculty union. “Most faculty are eager to get back in person but want to do so safely.”

Staff already was operating at reduced capacity because of exposures or infections, Calcado said. Officials also knew that even if faculty or other employees had only mild cases, an infection would inhibit their ability to physically report to work. But those infected with mild cases possibly could teach online, he said, which would allow the university to serve more students.

At Penn State, Wolgast said the university will continue to monitor community spread, severity of cases, vaccination rates of communities around its campuses, and hospitalizations. And it will continue to evaluate gatherings, events, and other activities, she said.

“With our students, faculty, and staff at University Park fully vaccinated at a rate of 90%, we believe we can — at this point — hold in-person activities safely with the additional mitigation measures we have in place,” she said, though that could change with pandemic conditions.

Penn State isn’t requiring students to be tested for coronavirus before returning, but it will continue to test unvaccinated students weekly. The university, like most schools, also will continue to require face coverings indoors.

The university’s approach has drawn criticism. A petition with more than 1,600 signatures of students, professors, and others has called on the university to postpone in-person instruction. Jesse Barlow, a Penn State professor who also serves as president of State College Borough Council, said he wishes the school would have required boosters and delayed students’ return.

“My concern is that the omicron wave has been causing high infection rates here just like every place else,” he said. “Now, we’ve got lots of people coming from all over the country back here. I can’t imagine that’s going to decrease the number of cases.”