New kitten entering home

[Nevicar]

Hello everyone!*

I have a question for all of you, because you know so much more about cats than I as a collective.

So here it is: I'm planning on getting a kitten of 8 weeks this weekend, but my parents are giving me scuff about some stuff I wanna clear up here. The kitten hasn't had any of it's beginning shots yet, which I plan to do the day after Sunday, and they feel that getting a kitten of that age would be a threat to our current older cat of about 11-12 years and make her sick. The kitten would be quarantined in my room on Sunday and only leave to get its first round of shots on Monday. So I ask you, what kind of threats does an 8 week old kitten pose to an older cat? The older one has had all vaccines when she was young and just doesn't have the updated rabies. Is there anything that can endanger her or make her sick without direct contact to the kitten?

Thanks so much!