There's anecdotal data about college/university study abroad programs being cancelled with students being ordered to return immediately from certain countries such as China, South Korea, Italy, and Japan. [Few programs send students to Iran.] These are generally organized group programs in which undergraduates can have lots or almost no contact with local students (and even local faculty, as some programs organize special classes taught by imported faculty). Graduate students and postdocs are more likely to be doing individual research overseas and might or might not be subject to these policies.

In addition, some universities are discouraging contact with foreign academics and researchers by suggesting that faculty avoid foreign travel and avoid inviting/hosting foreign scholars. Research conferences and similar events are subject to cancellation.

Sporting events are being evaluated, so don't make plans to attend anything without checking whether it will be cancelled and whether spectators will be permitted.

However, the most widely known lists give information regarding colleges and universities that plan to provide all courses on-line or remotely for the remainder of the term. CNN has a map showing seventeen such institutions currently but doesn't provide details for many of them, so it's hard to know whether all classes are involved and other details.

Nevertheless, the following places appear to plan to move to all on-line instruction immediately:

University of Washington (presumably all campuses, of which Seattle is the primary location)

Stanford: they're on the quarter system, so it's unclear (to me at least) whether the policy applies to the remainder of the winter quarter, all of spring quarter or both)

U C Berkeley

Ohio State (main campus is in Columbus)

Princeton

Columbia

Harvard (students are being told not to come back from spring break)
ADDED: Harvard students are being told that they have five days to move out of dorms. Either this is an overreaction or someone there knows more about outbreaks near Boston than the numbers are showing. This will be horribly inconvenient and expensive for many students.

Again, I would be inclined to assume that all campus events at these places are cancelled for the remainder of this academic year unless one has information otherwise. Graduation is likely to be done remotely too unless warm weather really does reduce the incidence of COVID-19 quite quickly. Don't make nonrefundable travel plans.