I think the best answer would be from Viking of course.
Are you asking "If you test positive" and have to be quarantined?
I have read that guests are sometimes quarantined in a different cabin on the ocean ships or brought to a hotel on a river cruise. So I think it all depends on the type of vessel and its location. I have even read where they separated couples to help prevent the uninfected person from being infected. So they do have protocols and will carry them out. Viking offers insurance that I am told covers expenses if get covid-19. A good travel agent and Viking expert would be my best advice to use. So they can answer all of your questions and make sure you are prepared and not worried about anything before your cruise.
Lastly, welcome to the community of Cruise Addicts. It's so nice to have you here.
John