FWIW I contacted and came down with chicken pox and never saw anyone with active chicken pox in the students I was in association with. So yes, I believe the doctor entirely. The virus has to replicate all over your body before your body succumbs to the disease symptoms.
How safe do you think unprotected sex and intimate kissing with a pre-symptomatic nurse would be?
Yup. Never really occurred to me that when I got chicken pox, I didn’t know of anyone before, during, or after who had it - ever.
Never mind the “WTF?” period in the onset of any disease where one has symptoms but has no notion what they are nor whether to do anything about them, the “I don’t feel quite right...” time before the “oh crap, I’d better see a doctor” realization.
Chicken pox is transmitted by aerosols, so you don't have to be in the same room at the same time as someone who is sick to catch it. You could catch it by walking by an open window. You could catch it by breathing the air in a room that someone with chickenpox recently, but no longer, occupies.
The chicken pox virus is completely different from the Ebola virus, in just about every way.