Earlier quoted context omitted.
I've added "for the rest of the semester", which is explicit about being temporary and I suppose implies enough about covid-19. (Submitted title was "MIT moves all classes online, requires undergraduates to leave campus".)
As a non-US national I never really know what a "semester" is with respect to US universities. Not sure what a better title would be though. The key information here in my opinion is that students are being told not o come back in a few weeks following spring break.
Many universities also offer a small number of courses during the summer break. Some universities allow certain courses to be only a half-semester in duration.