In late July, Jeremiah Monteiro, a rising sophomore at Purdue University, got a surprise visit from his school's mascot.

The black and yellow train, known as the Boilermaker Special , pulled up to Monteiro's family home in Naperville, Ill., and Purdue officials presented the sophomore with a Willy Wonka-inspired golden ticket worth $9,992, the equivalent of a year's in-state tuition at the Indiana school.

"I was really shocked," Monteiro says. ""I'm glad that not that many people were outside at that time."

Back in May, when Monteiro had shared his proof of vaccination against COVID-19 with Purdue, he had been entered in a drawing — and officials explained he was one of 10 students to win a golden ticket.

"Out-of-state tuition is very expensive, so I'm glad that I can use that and help my parents out with paying tuition," says Monteiro. He immediately FaceTimed his mother in India — even though it was nearly midnight there — to share the good news.

Purdue is among the hundreds of U.S. colleges that are counting on high COVID-19 vaccination rates to keep their campuses safe this fall. Colleges have adopted vaccine mandates , a few are charging students a fee for being unvaccinated and many are hosting vaccine clinics on move-in days. If all that wasn't enough, countless colleges are also offering flashy rewards to encourage students and faculty to get their shots.

At West Virginia University, students and employees who submitted proof of vaccination were entered in a raffle for a chance to win laptops, $250 gift certificates for Chick-fil-A and a free zip-lining session on the school's course. At Ohio University, prizes included a one-hour fall photoshoot, dinner with the men's basketball coach, a VIP ride in the school's homecoming parade and a drink named after the winner at an on-campus coffee shop.

"Incentives really work best when they're aimed at people who are not against being vaccinated, but they have for whatever reason not prioritized vaccination up until now," says Emily Largent, a professor of medical ethics and health policy at the University of Pennsylvania.

College students, she says, are in an age group that has likely not prioritized the COVID-19 vaccine, and incentive programs give them a "tangible and immediate" reason to get their shot.

"Puppy therapy" and a dunk tank are among the incentives at one college

The College of Charleston, in South Carolina, has promised to celebrate high vaccination rates with the return of some four-legged friends. Before the pandemic, "puppy therapy" was a regular campus feature, says Melantha Ardrey, director of residential life. When the student body is 70% vaccinated, therapy dogs will come back to campus, and fraternities and sororities can start recruiting in-person again.

When 80% of students are vaccinated, Ardrey says the university will host a campuswide pizza party.

And when 90% are vaccinated, students can expect a big splash: The school's president, Andrew Hsu, will sit in a dunk tank.

Ardrey says the college tried to design its incentives around College of Charleston traditions and social events that students could not participate in during the pandemic.

"We wanted to highlight that human connection, that traditional college experience that students have been missing," she explains.

She knows the college's 90% goal is ambitious, but she says, "We want our students to know this is important, and we want to be able to return to normal."

Ardrey hopes the program will help mitigate the virus's spread on campus. Last year, she says, college administrators worked hard to prevent outbreaks in dorms; they limited the number of students who could live in residential halls, and moved those who tested positive for COVID-19 into isolation spaces.

This year, with dorms fully occupied and fewer isolation spaces, Ardrey says it's even more important that students get vaccinated.

A vaccine incentive program saved one college money

Missouri State University is offering about $150,000 in prizes to vaccinated students. Those who get the shot (or shots) have a chance to win free housing, free tuition and free parking, among other things.

The cost of the prizes will be covered by private donations, says David Hall, director of university safety. The awards are a financial dream for many students — and, in some ways, for the university too.

"It reduces the need for testing and reduces the need for our COVID housing," Hall explains. "This actually is saving the university money, in addition to the benefits that we're getting to the students."

Missouri State is based in Greene County, a conservative area that voted for former President Donald Trump in the 2020 election. Hall was concerned about how the program would be received by the college's surrounding community, but he says he hasn't heard much criticism.

"There's an understanding of the economics of this and how it makes good financial sense," he explains. "We've not seen any significant pushback politically, even though we do live in a very conservative area."

Incentives only go so far

Case Western Reserve University, in Cleveland, offered vaccinated students a $500 textbook credit, free parking and a semester of free tuition. But those incentives only got them so far: The college says about 73% of students on campus were either fully vaccinated, or on their way to becoming fully vaccinated, by mid-July.

"We got stuck," explains Eric Kaler, the school's president. "It was clear that additional incentives were probably not going to be effective in moving us to the 95-plus percent level that we think is necessary."

The college decided to require vaccination, and Kaler says that requirement — in addition to follow up phone calls and emails to students who hadn't registered their vaccine yet — helped increase the vaccinated rate to 98% of students on campus.

Kaler knows not all universities are able to require vaccines, given legal and political constraints, but for his campus, it was the thing that worked.

Batool Ibrahim, a rising senior at the University of Nebraska-Lincoln, says it's time for her college to go beyond incentives.

The start of the fall semester is a couple weeks away, and with the surge of the delta variant, Ibrahim is worried. The Centers for Disease Control and Prevention recommends that even vaccinated people wear a mask indoors in areas experiencing high COVID-19 spread. Lancaster County, where the University of Nebraska-Lincoln is located, falls into that category, but the college isn't currently requiring vaccines or universal masking.

Monthly massages, football tickets and free ice cream are among the prizes the university is handing out to students and faculty who register their vaccination status this summer.

Ibrahim says those incentives can certainly start conversations about getting the vaccine, but she would like to see her school implement stricter health and safety protocols for unvaccinated students.

"While we're pushing students to get vaccinated on campus, we're battling with students that are coming from states where a mask mandate is banned ... or they're coming from states where the vaccine is more than questioned, it's a conspiracy," Ibrahim says. "I'm just realizing that we probably need to come at it from a lot more angles."

She commutes to campus from her family's home in Lincoln, and she's worried about bringing the virus home to family members who are immunocompromised.

"I'm actually very scared to go into class not knowing if I'm sitting next to students that are not vaccinated," Ibrahim says.

"This is literally life or death that we're talking about."

A university spokesperson told NPR that the school is working closely with the local health department to develop health and safety guidance, including around masking. Unvaccinated community members will also be subject to random COVID-19 testing.

Valerie Jones, an advertising and public relations professor at the University of Nebraska-Lincoln, says she has been closely following COVID-19 case rates this summer. At first, with vaccines widely available, she was optimistic about the safety of her classroom in the fall. She was even eyeing the university's grand prize for vaccinated faculty: a trip to Ireland to watch the Huskers play in the Aer Lingus College Football Series.

But now, with COVID-19 cases rising among children , Jones worries about bringing the virus home to her 7-year-old son and an 11-year-old daughter.

"It does make you think a little bit differently about how we interact and how you teach," Jones explains. "You do have to be a little bit more careful in the classroom."

For now, she's counting down the days until her daughter turns 12 and will be eligible for the vaccine.

Sneha Dey is an intern on NPR's Education Desk.

Elissa Nadworny contributed to this story.

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