Before it reopens next month, Colby College will require all students coming to its campus in Maine to be tested for the novel coronavirus. But that’s just the beginning of its pandemic safety plan.

The private liberal arts school will require everyone on campus, from the roughly 2,000 students to the college president, to swab their lower nasal cavities three times a week at the start of the semester. Then they’ll do it twice weekly until the term ends. A laboratory in Massachusetts will deliver results within 24 hours to the school in the riverfront town of Waterville.

It could add up this fall to 85,000 tests for Colby at a cost of as much as $2.5 million. That’s far more testing per capita than some major universities are projecting.

Of all the educational unknowns in an extraordinary year of disease and disruption, one of the most vexing for colleges and universities is this: How much viral testing is enough?

The answer depends on factors including where colleges are located, how many students are invited to campus, whether they take classes face-to-face and how much schools can afford to spend on health surveillance.

There is no national consensus on testing. Many schools are focusing on students and employees who have covid-19 symptoms or suspect that they were exposed to the virus that causes the disease. Some also plan to test dormitory wastewater and selected groups of students.

Colby, which plans to have classes in person as much as possible, has staked out a maximalist position: Test everyone, and test often.

“It’s really important to our students, faculty, staff and families that we have a model in place that does absolutely everything possible to secure their safety,” Colby President David A. Greene said. Frequent and universal testing, he said, will enable the college to isolate those who test positive “before they’re actually spreading the virus in a significant way. That really is what it comes down to.”

Behind the strategy is a desire to bring almost all of Colby’s 2,000-plus students to campus. How many will come is unknown.

“I definitely overall really appreciate the thoughtfulness” of Colby’s safety plan, said Ellie Batchelder, 19, a rising junior from Kittery Point, Maine. But she confessed lingering uncertainty. Batchelder, a violinist, worries that the pandemic might sideline the orchestra and other extracurricular activities. “There’s a lot of aspects outside of academics that are really important,” she said. “I’m still trying to decide if I will return.”

Viral testing will become an essential campus rite in the fall as colleges and universities seek to contain an infectious disease that has killed at least 139,000 Americans since February.

Most college students do not face as much risk as people who are older and have more health problems. But students can be asymptomatic carriers, posing a potential threat to others around them, from their professors to the staffers who clean their dormitories and serve their food. They also could bring the virus to campus from hometowns around the country and the world.

Confronted with those challenges as the virus surges in parts of the country, some schools plan to continue the remote teaching that began last spring. Others are pledging vigorous health and safety efforts as they bring students back — mindful that campus closure could lead to a plunge in housing and tuition revenue. But their viral testing programs vary widely.

The University of Florida, which has more than 50,000 students, will reopen its Gainesville campus without a universal viral testing mandate. Instead, students will be required to answer a health screening questionnaire and get tested if they have covid-19 symptoms. The university has set up a 10-station drive-through site for those who need or wish to be tested. “The Gator Nation will not be deterred,” the plan states.

The Texas A&M University System on Tuesday announced plans to offer “quick and easy access” to free viral testing on its 11 campuses. But the public system, which has 151,000 students, is not requiring tests for all who come to campus. System officials plan to distribute 15,000 test kits each month under an agreement with the California-based testing company Curative. That will support the system’s goal of reopening for the fall with residence halls occupied and a mix of in-person and online classes.

“The goal is to have a large supply of tests out there,” said Greg Hartman, chief operating officer and senior vice president of Texas A&M’s Health Science Center. In a perfect world, he said, the system would test everyone regularly. “But it’s super-expensive, obviously. Too expensive to do that across the board.” Hartman said Curative’s charge is $150 per test. That adds up to $2.25 million per month.

The federal Centers for Disease Control and Prevention recommends testing for students and others on campus who show symptoms of covid-19. It also recommends testing for those who have been in close contact with someone diagnosed with the disease and, in some cases, for those in a wider circle of people who may have been exposed to the virus in a residence hall, lab or lecture room.

But the CDC has not endorsed universal testing at colleges. Citing a lack of research, the agency said June 30 that it is “unknown” if a policy of testing everyone who enters a campus would curtail transmission of the virus more than measures such as social distancing, face covering, hand-washing and intensive cleaning. “Therefore, CDC does not recommend entry testing of all returning students, faculty, and staff,” the agency said.

Some experts say the agency should take a stronger stand. “The CDC’s rationale for inaction is akin to observing that seat belts save lives in Cleveland but refusing to recommend them in Cincinnati because that’s a different city and ‘you never know,’ ” Carl T. Bergstrom, a biology professor at the University of Washington, wrote in the Chronicle of Higher Education.

Bergstrom told The Washington Post that he thinks testing programs should depend on the size and location of schools as well as the prevalence of the virus in neighboring communities. Weekly testing could be feasible for some colleges, he said. “Twice weekly would be more in line with what I’d like to see.”

That is Colby’s formula. The college expects to obtain testing through the nonprofit Broad Institute of MIT and Harvard, a biomedical research center. The institute has performed more than 300,000 coronavirus tests this year and plans to partner with several Northeastern colleges and universities to conduct tests of students, staff and faculty. The price is expected to be $25 to $30 per test, the institute said, a bargain compared with rates elsewhere.

Among those working with the institute on testing are Bowdoin and Amherst colleges and Harvard University — all of which have limited the number of students on campus. Harvard, which plans only remote teaching for undergraduates, will require viral testing every three days for those living on campus.

Bowdoin President Clayton Rose said the 1,800-student college in Brunswick, Maine, expects to pay for about 35,000 tests in the fall term for students, faculty and staff, even though it will house only freshmen and certain others. Rose said prevention is most important — especially vigilance on hand-washing, mask-wearing and social distancing. Testing, he said, will allow the college to figure out where students, faculty and staff might be “slacking off.”

Genesis Cazalez, 21, a rising Colby senior from Houston, said she plans to return. But viral testing will not erase public health worries, she said. “I’m very cautious about having 2,000 students back on campus and in Waterville, and what that means for their safety and their health,” she said. “Yes, we’re going to be tested twice a week. That eases the tensions a little bit for the students, but I don’t know that it will ease the tensions for the community.”

Dan Shea, 58, a veteran government professor at Colby, said he is reassured by the testing effort. He plans to teach in person, wearing a face shield when needed, holding class outdoors when possible and relying on physical distancing.

“I’m feeling more comfortable about going to work,” he said. He recalled the traumatic days last spring when Colby sent students home. Shea hopes the school can avoid a replay of that tearful scene. “Students want to be there, and we want to be there,” he said. “We all want to come together. That’s what we do.”