More U.S. colleges and universities are announcing a return to in-person classes this fall, and some say they will mandate that students be vaccinated against the coronavirus before arriving on campus.

Cornell University in New York, Northeastern University in Massachusetts, Fort Lewis College in Colorado, St. Edward's University in Texas, and Brown and Roger Williams Universities in Rhode Island are some of the schools that have announced they will mandate vaccinations for the new semester.

Rutgers University in New Jersey, with 71,000 students, said inoculating the student community will "accelerate the return to a pre-pandemic normal on the university's campuses, including increased in-person course offerings, more on-campus events and activities," according to its website.

Nova Southeastern University in Florida, with nearly 26,000 students, announced April 1 that it will resume classes in person, encouraged by vaccine availability in the state, it said on its website.

By August 1, students, staff and faculty are to be fully vaccinated two weeks after two doses of the Moderna or Pfizer vaccines are administered.

"I'm definitely excited to go back to in-person classes. I miss being with in-person classes, meeting professors face-to-face, just meeting people in class," said Yemisrach Hailemariam, a sophomore from Ethiopia, who is studying neuroscience at Brown University.

"It's really not the same over Zoom," she said about online learning.

Students at both universities are expected to prove they've received a vaccination authorized in the United States. The U.S. Food and Drug Administration (FDA) has approved use of the Pfizer-BioNTech and Moderna vaccines. The Johnson & Johnson vaccine has been put on pause, according to the FDA, after reports of side effects involving blood clots.

"We would love for all our students to be vaccinated before they go home to either places in the U.S. or places in other countries, because if they go there unvaccinated, they could actually carry the virus to their families and communities," said Gerri Taylor, co-chair of American College Health Association's COVID-19 Task Force outside Washington. COVID-19 is the disease caused by the coronavirus.

International students' concerns

But where the more than 1 million international students who study in the U.S. get their immunizations is a concern, Taylor said.

"Because if they get immunized in their countries, the vaccine needs to be ideally approved" by the FDA, she said.

Neither the FDA nor the Centers for Disease Control and Prevention (CDC) in Atlanta has announced which vaccines provided abroad will be accepted in the United States, Taylor said.

"Some of these students have actually been vaccinated in their home countries, perhaps with a Chinese vaccine, or with Sputnik V, or with the AstraZeneca vaccine," said William Schaffner, professor of infectious diseases at Vanderbilt University in Tennessee. Sputnik V was developed in Russia. The AstraZeneca vaccine was developed jointly by the British-Swedish drugmaker and scientists at the University of Oxford.

Several nations have issued new guidelines over the use of the AstraZeneca shot after the European Union's medical regulator announced a link between the vaccine and rare, possibly fatal, blood clots.

"Will they be accepted as vaccinated when they come back to the United States? And if not, can they be revaccinated with one of our currently available vaccines? And as far as I know, there are no data available on any of that," Schaffner said.

International students say they are uncertain about where to get inoculated in the U.S.

Vaccination availability for young people has been a low priority in the U.S. until recently because that cohort has suffered the least proportionally from COVID-19 so far. Most people of any age have had to search the internet, looking to secure an appointment on various lists that offer vaccines — health care providers, convenience stores that have pharmacies, mass vaccination centers, big-box stores and sports arenas — waiting for their turn.

"It's really hard because we don't have a home state," Yemisrach explained. "Especially as a freshman, if you're an international student and you don't know how to navigate local health systems."

Although some universities have announced they will resume in-person classes later this year, it is not clear whether vaccination requirements will be universal.

Pomona College in California, Pennsylvania State University, Boise State University in Idaho, Harvard University in Massachusetts, and the George Washington University (GWU) in Washington are some of the many that strongly suggest vaccination but have not made it mandatory.

State laws guide schools

By law, universities can enforce inoculations if the area in which they are located also mandates that every resident be vaccinated.

Vaccination "is the best way to get over corona as fast as we can because it's really bad in the U.S. and it's not going to leave anytime soon. So, I feel like vaccinations are probably our best bet," said Ewenet Seleshi, a freshman studying criminal justice at GWU.

"I don't think that people should be forced to be vaccinated, unless they're going to places like university," said Ewenet, who is from the U.S. state of Georgia.

"States have the legal and constitutional authority to require that the people who live in that state be vaccinated, or to introduce a vaccine mandate," according to the Johns Hopkins Bloomberg School of Public Health in Baltimore.

Students can exempt themselves for religious or medical reasons. According to the CDC, some people reserve the right to choose not to take the vaccine because of a religious belief or because they say they may be at risk for an adverse reaction or have a medical condition.

If many people were to be exempted from the vaccine, then herd immunity — or making enough people immune so the coronavirus cannot spread — might not be enough. According to the World Health Organization, herd immunity occurs when a significant number of people within a population acquires resistance to the disease or virus either through infection or vaccination.

Fully vaccinated people should continue to wear a well-fitting mask, stay 2 meters apart from others, and avoid crowds and poorly ventilated spaces, according to the CDC. Dickinson State University in North Dakota will allow students not to wear masks if they have proof of vaccination, it announced.

"We are in North Dakota, a state where there is no statewide mask mandate at this point. … We are trading off additional protection of masks for what we believe will motivate our students, faculty and staff to get vaccinated," Stephen D. Easton, president of Dickinson State, told NBC News in March.

"The best we can do for most of the school year was social distancing plus masks. We now have another tool that is more powerful, which is vaccination," Easton explained.

"I'll still be following COVID measures, but I probably will just be able to just go out a lot more. I'll still be wearing my mask when I go places. I just probably won't be wearing a double mask. I know a lot of people here are talking about getting the vaccine and going to parties, so I don't think a lot of people will be following a lot of the COVID safety measures," GWU freshman Ewenet said.