I did my undergrad here in the US and will be starting my graduate studies this fall. My visa (F1) doesn't expire until 2021, and I already submitted my SEVIS transfer to the graduate school in order to receive my I-20. What I don't understand is a) Do I need to leave the States because my visa is under my undergrad school and not my graduate school (I'd rather not because of covid) ? and b) Can I use this visa to re-enter the States before it expires (as in, if I leave in June and come back in August for my program) or do I need a brand new one?