BOSTON (AP) — International students are returning to U.S. colleges in stronger numbers this year, but the rebound has yet to make up for last year’s historic declines as COVID-19 continues to disrupt academic exchange, according to a new survey.

Nationwide, American colleges and universities saw a 4% annual increase in international students this fall, according to survey results released Monday by the Institute of International Education. But that follows a decrease of 15% last year — the steepest decline since the institute began publishing data in 1948.

The upturn is better than many colleges were forecasting over the summer as the delta variant surged. But it also reflects continued obstacles as visa backlogs persist and as some students show reluctance to study abroad during the pandemic.

Universities and U.S. officials hope this year’s uptick is the start of a long-term rebound. As international travel ramps up, there’s optimism that colleges will see growth past their pre-pandemic levels.

“We expect a surge following the pandemic,” Matthew Lussenhop, an acting U.S. assistant secretary of state, told reporters. This year’s increase indicates that international students “continue to value a U.S. education and remain committed to pursuing studies in the United States,” he added.

Overall, 70% of U.S. colleges reported an uptick in international students this fall, while 20% saw decreases and 10% remained level, according to the institute. That’s based on a preliminary survey of more than 800 U.S. schools.

At least some of the increase is due to new students who hoped to come to the U.S. last year but delayed their plans because of the pandemic. All told, there was a 68% increase in newly enrolled international students this year, a dramatic increase compared with last year’s decrease of 46%.

For many schools, even a modest upturn is a relief. Over the summer, officials at U.S. universities worried that the delta variant would dash any hopes of a rebound. But for many, that did not come to pass.

In August, U.S. embassies and consulates in India reported that they had issued visas to a record 55,000 students even after starting the process two months late because of COVID-19.

Among those was Kedar Basatwar, who enrolled this fall in a graduate program for business analytics at Northeastern University in Boston, one of the nation’s most popular destinations for foreign students. The 24-year-old from Pune, India, held off applying to American schools at the height of the pandemic because he wanted to make sure he’d be able to attend classes in-person.

“My plan was always to come to the U.S. because the opportunities after getting a masters are so much more,” said Basatwar. “Also, getting a U.S. visa is one of the biggest achievements that we consider in India.”

At the University of Illinois at Urbana-Champaign, officials are seeing “a return to normal for our international populations,” said Andy Borst, director of undergraduate admissions. The university enrolled more than 10,000 international students this fall, which nearly offsets a 28% decline from last year.

“We just had this pent-up demand,” Borst said. “A lot of Big Ten schools saw increases beyond what we were expecting.”

At some schools with big brands overseas, enrollments rebounded past their 2019 figures.

At the University of Rochester in New York, enrollments from abroad surged 70% over 2019 levels, driven by a boom in graduate students, according to school data.

The vast majority of U.S. colleges returned to in-person learning by this fall, but not all international students are physically on campus. After last year’s shift to remote learning, many schools have continued offering online classes to students abroad.

Out of all international students enrolled at U.S. colleges this year, the survey found that about 65% were taking classes on campus.

Fangzhou Gu, a 21-year-old senior from Beijing, is among those who opted not to return to New York University’s Greenwich Village campus for her final semester this fall before graduating in December.

Instead she’s taking classes at the university’s outpost in Shanghai, an option offered throughout the pandemic by NYU, which has seen international enrollments increase 14% from 2019.

Gu said her remaining course load doesn’t require her to be in New York, and her parents are concerned about her venturing too far from home.

“Class and classmates are more close, which really gives me a sense of community that I have longed for,” she said. “Plus, the living expenses are less of a burden here.”

For some colleges, the new flexibility of online learning helped avoid further enrollment setbacks. In the past, students at the University of San Francisco might have been able to start the term a week late if they faced visa or travel problems. Now, those facing visa delays can arrive halfway through the term or later, and in the meantime study online from abroad.

That was the case for Vinh Le, who was unable to get to the airport in Vietnam’s Ho Chi Minh City in time for the start of fall classes. Instead, the graduate student studied online for more than two months until he could get his first vaccine shot, which allowed him to travel. He arrived at the University of San Francisco on Nov. 1.

International students are seen as important contributors to U.S. campuses for a variety of reasons. Colleges say they help provide a diverse mix of cultures and views on campus. Many end up working in high-demand fields after graduating. And some colleges rely on the financial benefits of international students, who are typically charged higher tuition rates.

Although many colleges avoided a second year of declines, there’s still concern that the upturn may be isolated to certain types of colleges. The survey found that, last year, community colleges suffered much steeper declines than four-year universities, with a 24% backslide nationwide.

Researchers are still analyzing this year’s data, but some worry community colleges may continue to lag behind.

There are also questions about whether the rebound will continue. New vaccine requirements for foreign travelers could make it harder for some students to get here, and colleges are expecting continued competition from colleges in Australia, Canada and other nations looking to boost international populations.

Still, officials at many colleges are optimistic. More vaccines are being sent overseas, and newly lifted travel bans promise to reduce barriers to travel.

Some also credit President Joe Biden for sending a message that America wants students from abroad. In July, the administration issued a statement promising a “renewed” commitment to international education, saying it would work to make overseas students feel welcome.

For Paola Giammattei, a 21-year-old junior studying at Case Western Reserve University in Cleveland, the concern now isn’t so much her classes, but whether companies will still be willing to hire foreign graduates on short-term visas, given the current job market.

In the meantime, the chemical engineering major has embraced the return of campus life after she attended classes remotely at home in El Salvador early in the pandemic.

“Being in a classroom, being able to engage with other peers and professors is awesome,” Giammattei said. “It is easier to differentiate and have a good life-work balance when everything is in-person and you have different interactions in different settings, not through a screen.”