Following up on L-1's questions, does your lease give the tenants (i.e. you guys) the right to change the locks on the apartment? The ones I have seen most often do not unless you provide a key to the landlord and do so with their permission.
Provided yours is a legal occupancy, you might want to point out to your roomie that you can legally break into the apartment if he locks you out. So, he can either give you a key, or he can share in the costs of damage to the door, lock, or a window as you force your way inside.
Maybe you can work out something with your roommate that will ease some of his concerns. Perhaps a shower and change of clothes immediately upon your return home? Something more? I applaud your desire to work, but there must be some middle ground ... unless your roommate is paranoid and/or a hypochondriac. I mean, every day you go out you could bring back a plethora of virulent bugs - COVID isn't the only thing out there.

