In a dramatic move, at least a dozen colleges and universities across the country have cancelled in-person classes and switched to teaching their courses online, as the battle against the novel coronavirus in the United States intensifies.

The cancellations have been focused in states hardest hit by COVID-19 cases, including, California, New York and Washington state, after the virus infected more than 800 people in the US and killed at least 28 according to official counts.

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On Tuesday, Harvard University in Cambridge, Massachusetts, asked its students not to return to campus after its spring break, which begins on Saturday, and said it would move to virtual teaching by March 23.

"The decision to move to virtual instruction was not made lightly," the university said in a statement. "The goal of these changes is to minimize the need to gather in large groups and spend prolonged time in close proximity with each other in spaces such as classrooms, dining halls, and residential buildings."

Columbia University, Princeton University, Stanford University, the Ohio State University, the University of Southern California and the University of Washington have all announced similar so-called "social-distancing" measures.

Princeton University in New Jersey said all lectures, seminars and courses would be moved online after its spring recess next week. Online instruction there will last until at least April 5. Stanford University, located in California's Santa Clara County, which currently has dozens of confirmed cases of the coronavirus, cancelled all in-person classes for the final two weeks of its winter semester. The Ohio State University suspended in-person classes through at least March 30.

Students carrying boxes to their dorms at Harvard University, after the school asked its students not to return to campus after spring break and said it would move to virtual instruction for graduate and undergraduate classes, in Cambridge, Massachusetts, US [Brian Snyder/Reuters]

Dozens of schools and houses of worship across the country have been closed, and conferences, sporting events and concerts have also been cancelled in an effort to slow the spread of the virus.

Quick shift

Bryan Alexander, a senior scholar at Georgetown University, said most universities have the adequate technological infrastructure to conduct classes online, but may face some difficulties with faculty who do not have experience with virtual teaching and students who do not have access to the necessary technology.

"The difficulty is faculty who don't have experience in teaching online, they have to shift quickly, as well as translate class materials online," Alexander told Al Jazeera.

"Not all students will have access to sufficient technology," he said. "If, at home, they don't have good broadband, the right hardware, this could be a problem that we have to scramble to fix."

Harvard student Tom Osborn, 24, from Kenya said he was "shocked" by the announcement, which gave students only five days to finish schoolwork, pack their belongings, say goodbye to friends and make travel arrangements.

"It's chaotic right now, we don't really know what is happening," Osborn told Al Jazeera.

Osborn, who took to Twitter to vent, said that for international students or those who are taking classes with a lab or studio component, attending online classes may not be feasible.

"It might be that I have to go online at 2am to attend classes," he said.

@Harvard's #COVID2019 response is a complete joke. How do they expect low income students, and international students, to leave campus on 5 day notice. And do I have to wake up at 2am in Kenya to attend zoom classes? #coronavirus — Tom L. Osborn (@TomLeeOsborn) March 10, 2020

Emily Philbrook, 18 a first-year international affairs student at George Washington University, which has not announced a shift to online courses, said physically going to classes was vital to her learning process.

"I like being in class, asking questions and being around my friends," Philbrook told Al Jazeera, "I like interacting with my teachers."

The virus - which originated in Wuhan, China, last year - has spread to more than 110 countries, areas or territories worldwide and infected over 100,000. More than 4,000 have died as a result of the virus.

For most people, the infectious respiratory disease causes only mild or moderate symptoms such as fever and cough and the infected recover within weeks.

For others, especially older adults and people with health problems, it can cause more severe illness, including pneumonia.