(CNN) Universities from California to New York have closed campus classrooms as the novel coronavirus has affected more than 100,000 people worldwide and its spread has transformed into a pandemic.

The cancellations were initially focused in states and areas hardest hit by the virus, including the Seattle area, California and New York.

In some cases, online instruction is being offered for a limited period, or through the semester. Some schools are telling students to not return to campus for 14 days after their return, depending on the laws in their state.

And many universities are issuing guidance on avoiding travel to China Italy and South Korea , as students are on or about to go on spring break.

These are some of the major institutions that have taken action, including canceling or temporarily suspending in-classroom instruction: